november 20, 2012 Plaats een reactie
NUTTELOZE OGEN : GROTBEWONERS
Er bestaan honderden soorten blinde dieren die leven in de totale duistenis van diepe grotten
Ooit beschouwde men de Blinde holenzalm als een zelfstandig geslacht, zelfs in een apart geslacht ( Anoptichthys), maar uiteindelijk werd aangetoond dat het in feite een afwijkende, in grotten levende, oog- en pigmentloze vorm is van de mexicaanse zilverzalm (Astyanax mexicanus), die in hetzelfde gebied de bovengrondse wateren bewoont.
Creationisten(van het “baraminologie”-type ) zeggen dan ook dat “morphen ” (en zeker ecomorphen) niets anders zijn dan voorbeelden van “microevolutionaire varianten binnen een “KIND ” …..
Daarbij vergeten ze steeds te definieëren wat “KIND” nu eigenlijk is ( op het niveau van subspecies , species, geslacht , etc . … ) en/of houden bewust de resultaten van hun uitgangsvorm van polymorfe stambonen oorsprongen van diverse kinds(volgens sommigen een 50-tal oorspronkelijke Multi-PURPOSE genotypes (= P Borger ) erg veranderlijk en multi toepasbaar ……..Bovendien verzwijgen ze de algemeen conventionele wetenschappelijke insteek dat ; varierende “microevoluties ” accumuleren in de stamlijnen tot macro-evoluties over grote geologische tijdspannes // In feite opereert de evolutie zelfs met verschillende snelheden(afhankelijk van de(ook wel eens veranderende ) frequenties aan “generatiewisselingen ” binnen populaties ingebed in die stamllijnen …..
De Mexicaanse tetra is een straalvinnige vissensoort uit de familie van de karperzalmen. De wetenschappelijke naam van de soort is voor het eerst geldig gepubliceerd in 1853 door De Filippi. ….Wikipedia
* Insect : de hawaaiaanse grotsprinkhanen Oliarus polyphemus
Oliarus polyphemus, Kipukapuaulu Cave, Kipukapuaulu, Hawaii Volcanoes National Park, Hawaii County, Hawaii 2
*spin ( Neoleptoneta myopica),
zoetwatergarnalen ( Dougherty Plain cave crayfish Cambarus cryptodytes).
Al deze schepselen bezitten wel ogen , maar ze zijn :meestal erg klein ,er ontbreken essentieele onderdelen of er groeit huid overheen .Het zijn echter wel degelijk ogen , die hun normale plaatsen innemen in de schedels , of aan het uiteinde van sprieten en uitstulpingen zijn geplaatst …. etc …Net zoals “normale “ogen bij sommige aan hen verwante soorten …. maar het zijn toch overbodige uitrustingen
Onwerkzame ogen blijken aanwezig te zijn bij dieren die ze niet nodig hebben ? domme en verspillende prutserij ?
The non-functioning eyes of burrowing animals, such as marsupial moles (order Notoryctemorphia: no lens or pupil, reduced optic nerve), golden moles, amphisbaeneans and naked mole rats (Heterocephalus glaber).
De buidelmollen zijn een orde van de buideldieren. De orde omvat slechts één familie, de Notoryctidae, met slechts één geslacht, Notoryctes, en twee soorten, de kleine buidelmol en de gewone buidelmol. Wikipedia
Useless eyes: river dolphins
Not all river dolphins are blind; in fact, Amazon dolphins (Inia geoffrensis) have quite good eyesight. However, most others have reduced vision. Most of their habitats are murky waters, where eyes are of little use.
And the designer’s gift of good sonar is perfectly adequate instead.?
Why, then, do Ganges and Indus dolphins (Platanista gangetica and P minor) have eyes ( or rudimentsd of eyes ) at all?
For their eyes lack a lens, leaving these species unable to resolve images: the most they can do is perceive the presence or absense of light (of which there’s rather little where they live anyway)... for which skull apertures, eyeballs, muscles, retinas and the rest, the same design as normally-sighted dolphins have, seems a bit excessive.
Whilst on eyes… is it not strange that the creator, having given the nautilus (Nautilus pompilius) an otherwise very good pinhole camera eye, chose not to give that eye a lens?
Most nocturnal vertebrates, from owls to cats, have a membrane behind their (backward) retina, the tapetum lucidum. This reflects back any stray photons, giving the retinal pigments a second chance to pick them up.
Seems like a good idea, yes?
It is strange, therefore, that the creator saw fit to omit this apparently very useful piece of design from nocturnal tarsiers (and other nocturnal primates, such as bushbabies, owl monkeys etc). These cute little prosimians clearly need to see well at night. At least, we can assume so, because they have eyes so huge that each is larger than their entire brain! These vast eyes can barely be swivelled in their sockets, so the tarsier design requires the addition of an extremely rotatable neck.
If they were designed to see in the dark, think how much better they could do so with a tapetum lucidum behind each retina too! Alternatively, if they had one, perhaps they would not need such huge eyes. A waste of materials, perhaps? Or might this be design constrained by history?
(The designer also forgot to include a tapetum lucidum in the eyes of owlet nightjars (Aegothelidae), and of the Galapagos swallow-tailed gull, all of which would presumably benefit from having it. And he obviously was not bothered about the low-light visual abilities of humans either, for we too lack a tapetum.)
Mammalian vision processing
Also strange is the fact that the part of the mammalian brain that does the image processing is at the back of the head, so the nerve signals have to travel further from the eyes than they might otherwise need to.
The vertebrate retina
The retina is the ‘screen’ at the inside back of each eyeball, onto which is projected the incoming light. It is made up of lots of photoreceptor cells with their associated out-going nerves, and the blood supply to them. The problem is, the photoreceptors are in backwards, pointing away from the incoming light: the ‘cable’ from each cell is therefore in the way, and trails across the eyeball’s inside surface to exit the retina at the correctly-named ‘blind spot’.
Now, the brain compensates for this, so we don’t usually notice it. But a design that needs compensatory mechanism for some aspect of it, is not a good design.
But to make matters worse, this design actually causes unnecessary problems.
The photoreceptors have delicate, hairlike nerve endings, which means they cannot be cemented firmly into place. Instead, they are loosely joined to a layer of cells called the retinal pigment epithelium. This absorbs stray photons that would otherwise blur the image, and contains the retina’s blood supply. But the connection between the retina and the epithelium is so fragile that the retina can detach, either due to a blow to the head, or often, spontaneously. Starved of their blood supply, the retinal cells die, causing blindness.
Strangely, the creator was able to put retinas the ‘right’ way round… in those pinnacles of His purpose, the octupus and squid. Not only do their eyes, which are basically the same design as vertebrate ones, have their photoreceptors pointing towards the light, and so lack a blind spot; with the nerves training behind them and embedded in their blood supply, the cephalopod eye is far less prone to detached retinas.
Locust wing nerve ‘wiring’
In the African locust (Locusta migratoria), the n
erve cells that connect to the wings originate in the abdomen, even though the wings are on the thorax. Nerve signals from the brain have to travel down the ventral nerve cord past their target, then backtrack through the insect to where they are needed.
The recurrent laryngeal nerve
The nerve ‘wiring’ of the mammalian larynx is also bizarre. Nerve signals for bodily operations travel from the brain down the spine, then branch off. Fair enough. The larynx is in the neck, so one might expect that the relevant nerve would come off the spine at the neck. And, it does: the recurrent laryngeal nerve originates from the spinal cord in the neck, as a branch of the vagus nerve. But then, bizarrely, rather than taking a direct route across the neck, it instead passes down the neck and into the chest, loops under the posterior side of the aorta by the heart, then travels right back up again to the larynx. Which is a waste of materials by anyone’s standard, but in the case of the giraffe, it implies a Creator so set on the mammalian Bauplan that an extra 10 to 15 feet of nerve is needed.
More on the recurrent laryngeal nerve here.
The human larynx-pharynx junction
Talking of larynxes, there’s the opening of the human larynx (leading to the trachea) being from the pharynx, so that swallowing impedes breathing (and vice versa). Not only that, but with the wind-pipe coming from off the food-pipe, there is a constant risk of choking. Before the Heimlich manoeuvre was invented, choking was one of the leading causes of accidental death; even so, thousands still die worldwide each year from inhaling their food. Children are more vulnerable because their airways are narrower. Great design.
Human ear-moving muscles
The cartilage-y bits which funnel sounds into the sides of our heads, which we usually call ‘ears’, are known more formally as pinnae or auriculae. (It’s actually only the most external part of the external ear, which is everything up to the tympanum (eardrum). And the human pinna (or auricula) has three muscles attached to it: the Auriculares anterior, superior, and posteriore. They naturally have a blood supply, and their own nerve wiring (by a facial nerve — the temporal and posterior auricular branches of cranial nerve VII).
Yet, as Gray’s Anatomy puts it, “In man, these muscles possess very little action: the Auricularis anterior draws the auricula forward and upward; the Auricularis superior slightly raises it; and the Auricularis posterior draws it backward”. They move our ears.
In other mammals however, these muscles possess a very useful action, rotating the funnel that is the pinna to point towards sounds. Human ears, being more or less flat and fixed to the sides of our heads, cannot rotate towards sounds… which doesn’t stop these muscles giving it a feeble go.
The ability of some people to wiggle their ears is, sadly, one of God’s lesser-appreciated gifts to us.
Aquatic embryos // Terrestrial salamanders, which live their whole lives on the land after hatching, have to return to water to lay their eggs.
Sea turtle eggs//Conversely, aquatic creatures such as sea turtles, which spend their whole lives at sea, have to struggle out onto land in order to lay their eggs.
Gill-less cetaceans //Cetaceans — dolphins and whales — have to breathe air, and despite being designed to live underwater, have to return to the surface regularly to catch their breath. They do not drown, since they do not inhale underwater, but they can suffocate if they don’t get to the surface in time.
This is especially a problem for newborn calves, which are born underwater. Taking the first breath is triggered by the touch of air on the skin, and post mortems of dead calves sometimes show that it never got to the surface to take that first breath.
So, why no gills? It’s not like the designer couldn’t include both gills and lungs if it saw fit, since salamanders and lungfish have both — though it is unclear why cetaceans should have to breathe air at all.
What’s more, cetaceans can suffer from the ‘bends’ — decompression sickness — if they surface too quickly, just like any other mammal. This is where nitrogen in the lungs — lungs, yeah? — is squeezed by the depth pressure out into the bloodstream as bubbles. When the mammal surfaces from depth, a lot of time needs to be taken so that the bubbles can be safely, gradually, returned to the lungs. So, whales don’t usually surface very quickly. But if they do, they can die just as unpleasantly as any other mammal in that condition. And odd thing for a creature designed by a high intelligence to be able to suffer from, no? [Notes / references]
Haemoglobin//Haemoglobin, the molecule which transports oxygen around our bodies in red blood cells, has more affinity for carbon monoxide than for oxygen. It is better at carrying this poisonous gas than at the job it was so intricately designed to do.
Mammalian foetal blood circulation//There’s two problems here. Firstly, in the mammalian foetus, the lungs are not yet functional, and the oxygen and carbon dioxide exchange takes place in the placenta. Here, oxygenated blood coming into the foetus mixes with deoxygenated blood that has already circulated. This is very inefficient, as it means much of the foetal body receives only partially oxygenated blood. In adults, the deoxygenated blood goes directly to the lungs for oxygenation before circulation to the rest of the body; the mixing does not happen because of the closed connection between the heart and the lungs.
Secondly, to make this rather circuitous circulation possible, there is a hole between the chambers in the foetal heart (the foramen ovale), and foetal blood vessels (eg the ductus arteriosus). These need to close off at birth for the transition to adult circulation. Sometimes they don’t, leading to two relatively common, and sometimes fatal, birth defects — so-called ‘hole-in-the-heart’ babies.
Could the designer have done it better? Sure! If the umbilical cord were inserted at the chest, rather than the belly, it would solve several of these problems, because the umbilical vein and umbilical artery could connect to the pulmonary vein and pulmonary artery. If this doesn’t take a genius to work out, where does that leave the designer?
Many thanks to Mr Darwin at IIDB for this item.
Snake lungs//The lungs of snakes such as blindsnakes and colubroids. They have two lungs in their elongated bodies: a ‘normal’ sized right lung, and a tiny left one. Why waste material with the small one? More surface area for respiration would be available if the space the little lung’s non-gaseous-exchange tubing takes up were given over, instead, to a larger-volumed single lung. After all, that is what is found in other snakes.
Amphisbaenean lungs//Amphisbaeneans — ‘worm-lizards’ — have the same oddity as the colubroid snakes above… but in them, it is the right lung that is reduced. The designer clearly couldn’t decide which poor design to stick with!
Cephalopod gills//The flow of blood and water through the gills of cephalopod molluscs (octopus and squid) is not a counterflow arrangement, and so the gills are far less efficient than they could be. Sure, they’re good, but they’re good despite this disadvantage. Counterflow systems, where two fluids move in opposite directions, maintaining as high a concentration gradient as possible the whole time, are so useful that they are found in a wide range of situations: lungs, fish gills, kidneys, cold-adapted animals’ circulation (eg penguin feet), and so on. Yet the designer decided against using this basic arrangement… only in cephalopods…?
Snake pelvises//Many species of more ‘primitive’ snakes (that is, creatues without legs, yeah?), such as pythons, have bits of pelvis, hindlimbs and hindlimb claws buried inside their bodies. These are, of course, of immense use to legless creatures.
Whale pelvises//Whales have, buried deep in their bodies, remnants of pelvis and hind limb bones. Even if (as is sometimes claimed) they do have a function, why are the bones in question bits of pelvis and limb?
The panda’s thumb//Why is the giant panda’s ‘thumb’ made of an altered wristbone (the radial sesamoid), rather than the normal digit? If the human hand were the ideal design, we should expect a normal thumb, not some different way of doing the same thing. And if six ‘fingers’ are better than five for grasping, why do only pandas have this feature?
Male mammal nipples//Male mammals have nipples. They do so because, in the embryo, the tissues involved start to develop before the two sorts of bodies (male and female) diverge. But given that most other sex differences are confined, naturally, to the separate sexes, it is a remarkably odd bit of design. Males, after all, do not and cannot feed their infants with these nipples. Why are they then not pointless and a waste of materials?
Almost as interesting is the fact that male nipples are fully capable of feeding an infant. If a man is given the right hormones, and he will grow breasts that will lactate. So males potentially could feed infants. Surely that would be an obviously beneficial trick? But no. The Lord giveth, and the Lord taketh away, it seems.
Waste of life//There is a phenomenal waste of life in nature, everywhere you look:
- Oak trees produce thousands of acorns, yet hardly any stand a chance of becoming trees.
- Many fish species produce thousands of eggs, in the hope that a few will survive. Herring (Clupea harengus) for example produce around 35,000 eggs per batch, while cod (Gadus morhua) produce about four million.
- Male animals produce millions and millions of sperm, yet almost none stand a chance of fertilising an egg. A human male produces around 350 million sperm at each ejaculation. The garden snail Helix aspersa, for instance, is hermaphroditic; sex is generally repeated with aound six partners during a mating season. Sperm from each partner have to fight their way up the reproductive system past a cavity called the bursa copulatrix. Only the fittest will arrive at their destination, a special vessel where they may be stored for as long as four years while they are gradually used to fertilise the snail’s eggs. As many as 99.98% of them will die and be digested before they reach their goal, the storage organ.
- Hundreds of millions of tons of pollen are cast into the air every year, with only the tiniest of fractions reaching its desired destination. (Mind you, compare Genesis 38:9-10: wasting one’s gametes was a serious enough sin for Onan to be killed in punishment. Yet the Good Lord is supposed to have created things which by their very naturespill so much seed on the ground?).
- Approximately a third of human pregnancies fail or spontaneously miscarry in the first trimester.
- Male elephant seals battle so furiously for females that great numbers of them die of bloody wounds.
- When a male lion takes over a pride, it will usually kill the cubs of the previous top male.
- The boom and (catastrophic for the individuals) bust of lemming populations.
Functionless flowers //Flowers on plants such as dandelions, which are apomictic (asexual) and thus do not need to attract pollinating insects. Many apomictic species also continue to produce pollen, which may trigger reproduction, but its genetic contribution is not used and is thus wasted.
Functionless flower parts// The non-functional stamens (male parts) in some female flowers, and the non-functional pistils (female parts) in some male flowers. Most flowers have both sexes of reproductive organs (stamens and pistils). Some however have only one or the other, making the flower male or female. So having both where only one set works is a waste of materials.
Snail sex//Sex for molluscs such as the garden snail mentioned above is no easy affair. After finding a mate, courting may take up to six hours, and involves circling, tentacle touching, and lip and genital biting. Finally they get together and, being hermaphrodites, insert their penises into one another. As they live in shells, their genitals are located in their heads. They then fire 1cm long calcium carbonate darts into each other.
Back when I was at school, I was told that these served to hold them together, but the truth is much stranger. The darts’ job is not to fix the snails together, but to fix the sperm contest in favour of the dart-thrower, by ensuring more of its sperm make it to the storage chamber.
The darts are fired as sex begins. As they plunge into the partner’s body like hypodermic needles, they transfer a chemical called allohormone. This makes the female part of the reproductive system contract, sealing off the entrance to the bursa copulatrix, and diverting the sperm straight to the storage organ. A snail that has been speared will store twice as much of its partner’s sperm as a snail that has not.
A design elegant in its simplicity? Nah…
(As reported in New Scientist, 2 November 2002.)
Spider penises//They don’t have them. Now, internal fertilisation of egg by sperm seems to be a Good Idea: it is an effective way to ensure that the gametes meet. This can be accomplished by the female squatting over a sperm packet; that is how some mites do it. But more obviously and, one might think, sensibly, males often have a penis — a structure to deliver the sperm.
A male spider delivers his sperm with his pedipalps. These appendages are located on his head (and are considered by evolutionists to be modified mouthparts). But inconveniently for the spider, the pedipalps are not connected to the part of the body where the sperm is made (spider gonads are, unsurprisingly, located in the abdomen).
So before copulating, the male deposits his sperm onto a small web he has spun especially for this purpose. He then siphons the sperm up into the pedipalps, like “drawing ink into a fountain pen” as Olivia Judson has described it. Only once his pedipalps are thus primed can he inseminate his mate.
Surely having the gonads connected to the pedipalps… or a penis-type arrangement located, well, anywhere the designer felt like, really… would be a simpler and more economical design…?
See eg: W S Bristowe (1958), The World of Spiders, p65-67.
Spotted hyaena reproduction//There are certain… oddities… about the reproductive system of the spotted hyaena (Crocuta crocuta). But I can do no better here than quote from this site (my emphases):
Female spotted hyenas bear, suckle, and care for their young like any female mammal. But although their genitals are clearly female in function, they are male in form. The labia are fused into what looks like a scrotum, complete with two pads of fatty tissue that resemble testes. In addition, the clitoris is elongated to the point that it is nearly the size of a male’s penis and is likewise fully erectile.
Astonishingly, females mate and give birth through the long, narrow canal running down the center of this “pseudopenis.” During mating it retracts much like a shirt sleeve being pushed up, and during birth it stretches so much that it looks like a water balloon. “From a human perspective, the process can be thought of as giving birth through an unusually large penis,” says Frank.
Whatever the cause, female masculinization is apparently a very successful strategy for the spotted hyena, which is the most abundant large predator in its range. But this success comes at a cost that is tremendously high for the spotted hyena–and presumably prohibitively high for other species. Notably, giving birth is difficult and dangerous, especially for first-time mothers. The fact that the pseudopenis has such a long, narrow birth canal is enough to make it a poor organ for delivering a baby. But there is the added complication that the end of the pseudopenis cannot stretch enough to accommodate passage of the baby: In a first-time mother, the baby tears its way out. “It’s the only time I’ve ever heard hyenas cry out in pain,” notes Frank.
Even worse, the umbilical cords are so short that many first-born babies die. At only six-inches long, the umbilical cord is far too short to traverse the foot-long canal down the pseudopenis, which means that either the placenta detaches or the cord breaks before the baby is born. (For comparison, in women the birth canal is only a few inches long and the umbilical cord is a generous foot and a half long.) The longer a hyena’s labor, the more likely her baby is to suffocate and be stillborn–and the more likely the mother is to die. In captivity, first-time mothers labor as long as 48 hours and nearly three-quarters of first-born cubs die. Without veterinary help, many of these mothers probably would have died along with their babies; in the wild, many females die at three to four years, the age when hyenas typically first give birth.
Manatee toenails//Manatee flippers have toenails. Why?!
Marsupial infants//Newborn marsupials infants are born from the usual opening, and have to wriggle arduously through their mother’s fur to reach the pouch and nourishment. Why are they not born either more fully developed (like placental mammals), or even straight into the pouch?
What is even more strange is that the designer — working with a fresh slate for each ‘kind’ of organism — should choose to use this clearly suboptimal design over and over again, in such diverse creatures as kangaroos, koalas, wombats, numbats, marsupial moles and thylacines. And quolls…
Eastern quolls//Quolls are Australian marsupial carnivores. They are overall rather cat-like, but with mouse-shaped faces. They are, in two words, dead cute. As with other marsupials (see above), baby quolls are tiny pink jellybeans, which have to wriggle through the fur from vaginal opening to pouch. Once there, they attach themselves to a nipple and stay there until ready to leave ‘home’. Unlike placental mammals, therefore, nipple use does not rotate among the young.
A female quoll has six teats. Which makes it rather odd that Eastern quolls (Dasyurus viverrinus) give birth to up to 30 young. So the 24 weakest / slowest to the nipples are guaranteed to starve to death.
Having at least three-quarters of your offspring inevitably die, because they can’t get at the food you provide them… is good design?
More on the quoll here.
Apoptosis//Apoptosis is a process in the development of an embryo which involves programmed cell death. Cells are formed… only to be destroyed. Now, it’s possible that this might be a sensible way to go about making some parts. But for instance, vertebrate distal limbs — that’s your legs and forearms — have two bones in them, the tibia and fibula, the radius and ulna. That’s how they need to end up, how they’re designed to be. So why do these two bones start out as a single bone, that then divides into two by the cells dying off? If two bones are required, why not make two bones? That happens elsewhere in the body. Why kill off cells that resources have gone into making? What a waste of materials!
Toothless creatures’ foetal teeth//The foetal teeth of anteaters and baleen whales, which are made, only to be reabsorbed.
Dolphin embryonic hind limb buds//As they develop, dolphins (and — an evolutionary prediction — other cetaceans, I’ll bet) start to grow hind limbs, which of course they do not have and do not need once they’re born. These are later reabsorbed.
So for what intelligent design reason do they have them?
See eg: Sedmera, Misek and Klima (1997): ‘On the development of Cetacean extremities: Hind limb rudimentation in the Spotted dolphin (Stenella attenuata)’, European Journal of Morphology 35(1): 25-30. Abstract.
Human embryonic tails// Between four to seven weeks of development, we humans have a tail. It is later reabsorbed. Not only that, but we share with mice (in whose genome they’ve been found) the same tail-making genes. It appears that there is a separate mechanism controlling the tail’s apoptosis (qv), so that the occasional human born with a tail isn’t like that because of the reactivation of old genes, but rather because the genes to remove it have malfunctioned. Erm, special genes to remove something we’re not supposed to have?
The human coccyx//If a single bone is required, why does the coccyx start as separate ones that just happen to look like little vertebrae, which then fuse into a single lump? Why is there a muscle — the extensor coccygis — which would flex these bones, if only they weren’t fused — isn’t that rather pointless? And why is the coccyx’s development controlled by the same genes that make tails in other mammals?
When a coccyx is longer and its bones not fused, we call that sort of coccyx a ‘tail’. Or conversely, a really shortened tail with the remaining bones fused would look different from a coccyx how?
Guinea pig tails//The tails of guinea pigs, which are present but which are so short (reduced?) they do not extend outside the body.
Peacock tails//The tails of peacocks are so long that the birds (which are a favourite food of tigers) can barely fly. Surely there are less dangerous ways to attract females?
Dietary requirement for vitamin C//Apes and humans require vitamin C in their diets… which is rather odd, because most mammals synthesise their own. Yet although we humans cannot; we do have the same gene for this that they do… but it is broken! And it is rendered non-functional by precisely the same mutation in all the great apes. Coincidence? And how loving of the creator to give people without adequate diets scurvy!
Grass as a food//All those animals that are ‘designed’ to eat grass. Yet grass is a terrible food. Why does it contain so much silica, if not to protect itself against… the animals that were designed to eat it…? And it is deficient in minerals, so much so that animals have to migrate for hundreds of miles to get to ‘salt licks’, and elephants have excavated whole caves in their efforts to get minerals from the rock.
Cellulose digestion//What’s more, ungulates can only get the little nutrition they do from grass because of the millions of bacteria and protozoa in their guts that break down the cellulose that makes up the plant cell walls. Enzymes are readily apparent in animals to break down other foodstuffs. Surely the designer could have given plant-eaters an enzyme or two for this for themselves — after all, ‘mere’ bacteria can do it!
The Chinese grass carp//In a similar vein, the Chinese grass carp, Ctenopharyngodon idella, grazes on aquatic plants and, during floods, on land vegetation. It has specialised pharyngeal teeth that enable it to break up leaves, and so access the cell contents. So the creator clearly intended it to be able to eat these plants. Yet like most vertebrates, the cellulose itself, and the many unopened cells, pass undigested through the gut. If only it had the appropriate gut bacteria… (Did the intelligent designer just forget the grass carp when he was giving out the bacteria? Well I suppose there are a lot of species, so he can’t be expected to remember everything.)
Aphid symbiotic bacteria// Why do aphids need bacteria living inside of them to produce dietary supplements, when a reasonable designer would have given aphids all the biosynthesis capabilities needed to live off of plant sap?
See eg Shigenobu et al, Nature 407, 81-86 (2000). Abstract.
Convoluta flatworm mouths//Flatworms of the species Convoluta roscoffensis are green because their translucent tissues are packed with Platymonas algae. The algae live, grow and die inside the bodies of the worms. Their photosynthetic products are used as food by the worms, and the algae recycle the worms’ uric acid waste as food for themselves. The worms’ mouths are superfluous and do not function after the larvae hatch: worm plus algae plus sunlight is a self-contained unit. For what divine design purpose do the flatworms have mouths, as other flatworms have?
Animal chlorophyll//And just how useful would it be in times of hardship if any animal could make its own food? Some chlorophyll (or strategically placed algae!) would do it. But only plants have it.
Mayfly mouths//Many groups of insect divide their lifecycles up into a feeding stage — a caterpillar, for example — and then an adult stage, whose main job is to find a mate. In many species, though, such as mayflies, that is just about all they do — they do not even feed (and hence have a short adult life). And yet these adults have mouthparts — often reduced — that serve no purpose.
The mammalian tidal respiratory system. Because of the way it works, mixing fresh air with ‘used-up’ air, it is not very efficient. Is there a better system available? Sure! Birds have a through-flow system, whereby the incoming air is not mixed with the deoxygenated air. This is not just a bit more efficient, it is in the order of ten times more efficient.
So the Intelligent Designer gave bats (eg pipistrelles) a hugely inferior lung ventilation system to that of birds (eg nightjars)! And used the bird one in kiwis, and the bat one in humans, whales and cheetahs. Go figure.
Echidna spurs//The monotreme echidna (‘spiny anteater’) males have non-functional and reduced poison spurs on their hind legs. Reduced relative to what? Why, the working version found on the hind legs of males of another creature. And that is… the hedgehog? Porcupine? Nope, the only other egg-laying mammal, the platypus.
Pouchless penguins//The echidnas above lay eggs… and put them straight into their pouches. One might think that if a pouch is a Good Idea™ for an egg-laying thing, that it would save birds having to fanny around with nests. Ah, you might say, but birds have to fly, and having a nestfull of eggs or chicks in a pouch would make flight difficult. Sure… but not for flightless birds!
This is especially relevant for penguins. Penguins, like every other bird, need to keep their eggs warm. Living in the silly places they do, however, means they can’t have a nest (made of what — shaved ice?). Instead, the poor little buggers have to sit the egg on their feet and cover it with a flap of groin skin. When they do this, they can hardly move, and they have to swap it over to other penguins if they want to go and grab a bite to eat, which often involves rolling it along the ice. This is a dangerous way of keeping an egg warm. Imagine how much easier it would be for them to have that flap of skin surrounded with contractile muscles, like a marsupial pouch between its legs. If it was really good at sealing (with glands producing water-resistant mucous?), then the bird could even take the egg with it when it goes swimming for food.
There is no questioning that a better developed pouch would be useful to penguins, given that they try as hard as they can to have one anyway. And, a sealable pouch design was known to the Creator, because he used it in the yapok (water opossum, Chironectes minimus). But… but… the eggs might get broken! So, uh, how about having live young?
Many thanks to Doubting Didymus at IIDB for this item.
Cell organelles//Cell organelles such as mitochondria and chloroplasts have their own DNA, which is inherited separately from the rest of an organisms’ genetic material. Why should the code for small elements within each eukaryotic cell be inherited separately and differently from that which forms the rest of the organism in all its intricacy — the leaves, bone, teeth, eyes, antennae or brains? An odd design — and the numerous structural and biochemical resemblances between these organelles and existing parasitic bacteria are mere coincidences, of course.
Human limb regeneration.. or rather, our lack of it. If a ‘lowly’ salamander loses a limb, it can grow another one. It does this by reactivating the genetic instructions for limb formation that, in the embryo, formed the limb first time round. If we are such important creatures to the Creator, why did he not bother to endow us with this ability? Why do mammals in general not have this blatantly useful feature?
Flatfish skulls//The twisted skulls of bony flatfish (order Pleuronectiformes): around 500 species including halibut, plaice, sole and turbot. If you are a fish and want to hug the contours of the sea bed, there are two ways your body can be flattened. The most obvious is front to back, laying on your tummy, as rays and some sharks are. Sharks are generally already slightly flattened dorsoventrally. Most bony fish, however, tend to be flattened in a vertical direction (higher than they are wide). No surprise to an evolutionary biologist, then, that those bony flatfish that do swim at the bottom are flattened sideways, and lay on their side.
The problem with this is that one eye would always be pointing at the sea bed. They solve this by the skull contorting during development, so that one eye migrates to the other side. You will notice though that their mouths are still sideways on. They are cartoon stereotypes of what a mutant should look like. How is this ‘intelligent design’, rather than design constrained by history, by the materials it started with?
The human appendix//Why is such a great shape… if the idea’s for it to be a pocket to trap bacteria in, that is. It is common (about 15% of everyone and about 7% of US residents are affected at some point in their lives) for it to become distended and blocked, so that the bacteria can invade the wall, leading, untreated (as it would have been for nearly all of our past), to potentially lethal perforation.
a mechanical engineer, a chemical engineer and a civil engineer were discussing the human body in the pub. “The body was clearly designed by a mechanical engineer… look at all the levers and joints.” “No no no, it was obviously designed by a chemist, it’s full of amazing chemical reactions!” “I’m sorry”, said the civil engineer, “but it was undoubtedly a civil engineer. I’ve run countless sewage pipes through recreational areas myself…”
The human spine//Bipedal vertebrates usually carry much of the spine roughly horizontally, and balance it with a tail. Equally, a string of cotton reels with spongy cushions between is a good cantilever bridge type design for flexible quadrupedal running. But it’s a lousy thing to stand on its end and withstand the compression strains of vertical bipedalism. Compression strains are best absorbed by pillars. If you want the pillars to be flexible, you put joints in them. In biology, we have examples called ‘legs’.
And why thread so important a feature as the spinal cord through the middle of this, where disc damage can cause anything from pain to paralysis?
The spine’s ‘design’ thus results in back pain which causes over 149 million annual days off work in the U.S. alone, costing $50 to $100 billion in lost wages and medical costs, 80% of people being affected by back pain at some point in their lives, backache during pregnancy (extra weight pulling in an out-and-down direction it can’t happily support), and why you find, if you’ve ever ‘slipped’ (herniated) a disc, that about the only comfortable position is on all fours.
Like most beetles, they have wings… but these are sealed in beneath fused wing covers (elytra), and so the beetles are flightless. For darklings, the fused elytra help conserve water; for others they are a better protection for the abdomen. Wings are obviously not needed for flight for ground-dwelling beetles. The question is, why is the shell on their backs made of wing covers, and why are there (often greatly reduced) wings beneath them? Wings that cannot work on creatures that do not need wings at all?!
Halteres//Instead of the two pairs of wings that most flying insects have, flies (Diptera) have one pair, and instead of the second pair, they have a pair of tiny halteres (‘balancing organs’). Halteres are a neat piece of kit. Many flies can perform amazing aerial acrobatics: they can hover, rotate on their own axis, fly through spaces little wider than their wingspan, and even fly backwards. All these abilities are aided by the halteres, which act like tiny gyroscopes. The sensory organs at the base of each haltere form three groups at right angles to each other, which allows the fly to tell how fast it is flying and turning, and whether it is being blown off course.
Halteres are, then, very well designed for this purpose. And yet… remember where they are located? There is a mutation in flies (best studied in Drosophila melanogaster fruitflies) which ‘switches on’ the homeobox Ultrabithorax (UBX) gene. Guess what? The halteres grow into a second pair of wings. If halteres were balancing organs, specifically designed for that job, how can they become wings — that is, things designed for a different purpose? Surely it’s not because that’s what the used to be…?
Booby nests//As is well known, birds generally make nests. Well, there’s a bird called the blue-footed booby, whose females lay their eggs on bare rock and build no nest. Yet the male still collects nesting materials and presents them to the female during courtship, just as other species that actually build nests do.
Gannet nostrils//Birds of the family Sulidae, the boobies and gannets, are diving birds, plunging from height into the water. And one of their adaptations to this is that they lack external nostrils. This makes sense: the water would otherwise get shoved up their noses on impact.
So is this intelligent design? Not exactly. For though they lack external nostrils, they have everything else that constitutes nasal airways inside their beaks — the septum, choana etc — it’s just that the nostrils are sealed off at the outside. Having nasal airways that cannot work (since they are blind-ended) is pretty pointless design. Why bother having them at all?
See J B Nelson (1978): The Sulidae: Gannets and Boobies. Aberdeen University Study Series 154, Oxford University Press. Many thanks to Urvogel Reverie at IIDB for the reference.
External testicles//Mammalian testes form inside the body, and then have to pass out through the abdominal wall to the scrotum so they can be at a more conducive temperature for sperm formation. Not only is that odd (why can’t sperm be made at body temperature?), but the process leaves a weak spot in the muscle wall. This ‘inguinal ring’ is liable to herniate, which both obstructs or strangulates the bowel and stifles blood flow to the testicles.
Also, testicular temperature regulation requires a huge investment of musculature and blood flow. Interior testicles would be much more efficient and protected to boot (no pun intended).
Non-coding DNA//Most organisms, humans included, contain in every cell vast quantity of non-coding or ‘junk’ DNA: pseudogenes, introns, transposons, retrotransposons, etc, which does little for its owner except get itself copied. Pseudogenes, for instance, are chunks of DNA which have a resemblance to known genes that is too improbable to be coincidence, but which are not prefaced with a ‘start’ codon. Thus the DNA-to-RNA transcription system doesn’t know that ‘here is a gene to be expressed’.
This is not just an idle observation: about 98% of human DNA is ‘junk’ DNA, not coding for any protein. For example, the Alu sequences are repeated some million or so times, and this one family alone accounts for about 5% of our DNA. (However, Alu might have a use after all, but it would appear that this use developed after the Alu’s appeared, because most living things do just fine without them.) In Drosophila fruitflies, 40% of the genome is taken up by three sets of so-called ‘satellite DNA’: pieces just seven ‘letters’ long, with no ‘meaning’, repeated eleven million, 3.6 million and 3.6 million times.
Using more materials than are needed is not good design.
Birds do not have full fibulas (the second, smaller lower leg bone); it is that little splinty thing that you find down the side of a chicken drumstick. And their tarsals (ankle bones) are fused into a single lump and to the other leg bone, the tibia, forming the main part of the drumstick, the tibiotarsus. But birds have genes, normally non-functioning, for making complete fibulas with separate tarsals .
Horses have a single toe on each leg. But horses have genes, normally non-functioning, for extra toes.
What are genes for making these things doing in creatures that don’t need them, don’t normally have them… and if separately designed, never have had them?
Hollow ostrich bones//Ostriches, which are not known for their flying abilities, have hollow bones. They share this feature with flighted birds (except in their legs, where strength is now a survival attribute that natural selection can operate upon). Being ground-based, such weight-reduction does not seem appropriate… but if this is a useful feature, why do other land animals not have it?
Solid bat bones//Bats, which are well known for their flying abilities, share with terrestrial mammals — from elephant to mouse — their usual solid bone structure. One has to wonder why the designer did not give bats the hollow, weight-reducing, bone structure design he used throughout birds (whether appropriate or not). Conversely, if solid bones are better for a flying thing, why do no flying birds have this feature?
The genetic code//DNA has a remarkable copying fidelity… yet mutations — errors — are far from rare. If the Good Lord wanted all his creations to be separate, immutable kinds, all he had to do was make the copying mechanism flawless. Meiotic recombination and outcrossing (sex) would still make different individuals. Hey presto — no evolution. But the system is flawed… so the designer must… want evolution?
Even mere mortal Francis Crick, co-discoverer of DNA’s structure with James Watson, proposed a more efficient and robust ‘comma-free’ code than the real one that living things use, before the real one was known. Crick’s code design avoids frameshift mutations and has precisely as many states as there are amino acids to be coded for. Rather more optimal… and no known life uses it.
Greenland shark eyes
Somniosus microcephalus.//Greenland Shark
Sharks hunt, up close at least, by sight. Most Greenland sharks(Somniosus microcephalus), however, most are nearly blind (usually only one eye is affected )
This shark frequently has a relationship with a parasitic copepod, Ommatokoita elongata, that attaches itself to the cornea of the eye and feeds on the shark’s corneal tissue; the resulting scar tissue leads to partial blindness of the shark. However, studies show the Greenland shark can probably detect light. The copepod is a whitish-yellow creature that was said to be bioluminescent, but this was proven false by American shark parasitologist George Benz.
Some theorize that the function of the copepod is to attract prey for the shark, like a fishing lure. This is suggested by the fact that these normally sluggish sharks have been found with much faster-moving animals (such as squid) in their stomachs. However, the theory of copepods acting as fishing lures is weakened by reports by Canadian Researcher William Sommers in Arctic Canada, where he witnessed Greenland sharks snatching caribou from the water’s edge.
But nevertheless , where is the intelligent design in such a complex set-up, and why does the (designed ) shark needs a good and and a bad eye (so the shark is going to be parasitised to half- blindness as part of the design? )…. first having eyes, then having one go blind ?
Groenlandhaai oog met parasiet
Lesbian lizards//Some Cnemidophorus whiptail lizards are parthenogenic — they are all females, no males. But it’s been found that an individual’s fertility increases when another female acts like a male and attempts to copulate with it (they apparently do this quite regularly and quite unprovoked by experimenters, by the way).
These lizards’ nearest relatives — oh okay, the ones most similar to them in geography, genetics, anatomy and biochemistry — are sexual species.
And the hormones for reproduction in these others are stimulated by sexual behaviour. So it’s no surprise — to ‘evolutionists’ — that although Cnemidophorus are parthenogenetic, simulated sexual behaviour increases fertility. But it’s a bit of an odd thing to design. (Especially if the designer were the Biblical God, for Leviticus seems to be rather against girl-on-girl action…)
See Crews and Young (1991): ‘Pseudocopulation in nature in a unisexual whiptail lizard’, Animal Behaviour 42: 512-514; Crews and Fitzgerald (1980): ‘ “Sexual” behavior in parthenogenetic lizards (Cnemidophorus)’, Proceedings of the National Academy of Science 77: 499-502.
Cneidophorus hagedisen waarvan geen mannetjes bestaan en die aan parthenogenese doen, ,in feite natuurlijke klonering van zichzelf…..met literatuurverwijzingen ;http://repertorium.library.uu.nl/standlijsten/diergl.htm
New Mexico Whiptail
((Hybrid origin of a unisexual species of whiptail lizard, )Cnemidophorus neomexicanus
(Variation in and distribution of the unisexual lizard, )Cnemidophorus tesselatus
all female lizards
Gastropod development//As they develop, all gastropod mollusc larvae do a 90 to 180 degree twist, so that their mantle, kidney opening and anus are sticking out over their heads. Which seems rather odd design, but okay… The really stupid design is the fact that slugs (subclass Pulmonata) and sea slugs (subclass Opisthobranchia) then do an untwist, and straighten their bodies out again.
Goose bumps//Since humans (especially women) generally have little body hair, it is pointless having the same system of muscles (the arrectores pilorum) and sympathetic nerves which in most mammals raises the hairs in response cold or fear. Nevertheless, we get goose bumps (cutis anserina). What’s more, if our skin is meant to be mostly bare, why do we have the tiny ineffectual hairs (and separate muscles and nerves for them) at all?
Human grasping reflex//The grasping reflex in human babies would only seem to make sense if we used to have rather more body hair, like other primates. It appears a rather pointless design otherwise.
In gebieden waar filariasis endemisch is zullen nieuwkomers – in tegenstelling tot de aanwezige bevolking die chronisch is blootgesteld aan filaria – wel snel symptomen kunnen krijgen. Wereldwijd lijden ca. 120 miljoen mensen aan filaria waarvan ca. 40 miljoen ernstig. Een derde van patiënten leeft in Afrika, een ander derde in India en de rest in vooral Zuidoost-Azië. Vele patiënten worden sociaal buitengesloten als gevolg van deze ziekte, die ernstige misvormingen teweeg kan brengen.
Iemand met weinig wormen in het lymfestelsel zal in het algemeen hier geen klachten van hebben. Toch kan bij nader onderzoek van deze mensen al wel schade aan bijvoorbeeld de nieren worden ontdekt en kunnen er miljoenen microfilariae in het bloed circuleren. Bij grotere aantallen wordt de afvoer van vocht uit weefsel bemoeilijkt. Dit kan zwelling en verdikking van de huid geven. Bij de geslachtsorganen kan het leiden tot een sterk opgezwollen scrotum, bij vrouwen tot vergrote buitenste schaamlippen. De armen en benen kunnen ook zijn aangedaan, deze worden eveneens opgezwollen. Deze symptomen worden gevangen onder de term elefantiasis en lymfoedeem. Dit wordt veroorzaakt door obstructie van de lymfevaten of door verlittekening hiervan door een immunologische reactie van het lichaam. Naast de elefantiasis kunnen huid, lymfevaten (lymfangitis) en de lymfeknopen gaan ontsteken. Ook komen hierbij koortsperioden voor. Door zwelling en aantasting van weefsel in de door elefantiasis aangedane lichaamsdelen ontstaan daar ook vaak andere infecties.
Vroeger werd rond middernacht (22.00 – 02.00 uur) bloed afgenomen omdat dan de meeste microfilariae in het bloed circuleren. Tegenwoordig wordt vaak getest op de aanwezigheid van antigenen van de wormen. Er bestaan hiervoor eenvoudig uit te voeren testen zonder dat daarvoor een laboratorium nodig is. Bij een nog actieve infectie kunnen anti-filaria IgG4 antilichamen worden aangetoond. Bij patiënten met lymfoedeem gaat het vaak om infecties van jaren geleden waardoor de test op antistoffen alweer negatief kan zijn. Er bestaat ook een polymerase kettingreactie om de infectie aan te tonen.
De andere infecties zullen moeten worden behandeld. Ook moet geprobeerd worden de lymfestroom weer beter op gang te krijgen. Vooral de microfilariae van de draadwormen worden gedood door albendazol en diethylcarbamazine (DEC). Om in een gebied te proberen de filaria onder controle te krijgen kan eenmaal per jaar een dosis DEC worden gegeven. Hierdoor zal ongeveer een jaar lang het aantal in het bloed aanwezige microfilariae sterk afnemen waardoor de transmissie via muggen wordt afgeremd. Een ander medicijn dat met name de microfilariae van deze draadwormen doodt is ivermectine. Onlangs bleek ook het antibioticum doxycycline werkzaam te zijn. Dit antibioticum doodt een in de draadworm aanwezige symbiont, de Wolbachia-bacterie, waardoor ook de worm zich niet meer kan voortplanten en tevens zal overlijden.
° Kissing Bugs (Triatoma protracta and others).
Tungiasis is een parasitaire huidziekte, vaak aan de voeten (tenen, hielen), veroorzaakt door de vrouwelijke zandvlo (Tunga penetrans) die zich ingraaft in de dermis van de gastheer. Tungiasis komt voor in Zuid en Midden-Amerika, het Caraïbisch gebied, Afrika, Pakistan en India. Honden, katten, varkens en ratten zijn de belangrijkste reservoirs. Wordt steeds vaker in Nederland gezien als importziekte door toename van het reizen naar de tropen (werk, vakantie). Tunga penetrans heeft vele andere namen: zandvlo, ‘jigger’ (Engels), ‘chique’ (Frans), ‘sika’ (Surinaams), ‘bicho de pe’ (vlo van de voet, Portugees). Tungiasis behoort tot de grotere ectoparasitosen, samen met pediculosis, scabiës en cutane larva migrans, substantiële morbiditeit veroorzakend in endemische gebieden.
De volwassen vlo is roodbruin, het mannetje is ongeveer 0.5 mm lang, het vrouwtje 1 mm. Ze leven bij voorkeur op een warme, droge, schaduwrijke en zanderige bodem, in stoffige hutten, veestallen en andere dierbehuizingen. Het bevruchte vrouwtje probeert zich in de huid van mens of dier in te graven. Na de huid binnengekomen te zijn, vergroot zij zich door bloed en ontwikkelende eieren. Als haar abdomen zwelt, kan zij een afmeting van een centimeter bereiken. De kop van de vlo dringt door tot in de dermis. De achterste abdominale segmenten (het neosoom) blijven door een gat in de hoornlaag verbinding houden met de buitenwereld, zodat de vlo kan blijven ademen en excreet en rijpe eieren naar buiten brengen. Honderden eieren worden op deze manier in een periode van ongeveer drie weken uitgestoten. Nadat de eieren naar buiten gebracht zijn, sterft het vrouwtje in situ, verschrompelt en wordt uitgestoten.
Aspect van de laesie is afhankelijk van de fase waarin de infectie zich bevindt. Er kunnen vijf stadia worden onderscheiden:
- Stadium 1: (vlo in statu penetrandi, 30 minuten tot enige uren)
Op de plaats van penetratie is aanvankelijk een kleine erythemateuze papel met een zwarte pit zichtbaar, met of zonder erythemateuze halo. De patiënt klaagt vaak over jeuk.
- Stadium 2: (beginnende hypertrofie met formatie van neosoom)
Laesie duidelijker aanwezig, groeiende wittige papel ontstaat met in het midden een zwarte punt (het anale / genitale deel van de vlo) omgeven door erytheem.
- Stadium 3: (maximale hypertrofie, twee dagen tot drie weken na penetratie)
Hypertrofie wordt macroscopisch zichtbaar, een zwelling met scherpe begrenzing en vastelastische consistentie ontstaat, frequent omringd door lokale desquamatie. Typisch voor deze fase is het uitstoten van eieren en faeces. De laesie wordt nu als pijnlijk ervaren, er ontstaat een vreemdlichaam reactie bij de patiënt.
- Stadium 4: (drie tot vijf weken na penetratie)
Een zwarte crusta bedekt een naar binnenwaarts gekrulde laesie met hierin de dode parasiet. De dode vlo wordt in de dermis van de gastheer geëlimineerd, een circulaire depressie in de epidermis achterlatend.
- Stadium 5: (zes weken tot enige maanden na penetratie)
Een rond litteken in het stratum corneum is karakteristiek voor dit stadium.
Typisch voor T. Penetrans is dat vaak de hielen, het periunguale deel van de tenen, of het gebied net onder de nagelrand is aangedaan, de reden hiervoor is onbekend. De zandvlo kan ook op handen, ellebogen, billen en in de genitale regio worden aangetroffen. De vlo kan tot 250 keer haar eigen lengte springen. Als zich meerdere laesies tegelijkertijd voordoen, zijn de parasieten vaak in clusters aanwezig, vaak op hielen, tenen en voetzolen. De aandoening kan gecompliceerd worden door secundaire superinfectie van de laesie(s). Vaak door stafylokokken, streptokokken, maar ook Clostridiae kunnen hierbij betrokken zijn. Niet-gevaccineerde individuen kunnen door tungiasis met tetanus geïnfecteerd worden. Bij ruptuur tijdens verwijdering, waarbij monddelen van de parasiet blijven vastzitten, kan er forse lokale ontsteking ontstaan.
DD (afhankelijk van stadium infectie):
Stadium 1: vreemd lichaam reactie, splinter, zee-egel punt.
Stadium 2: (persistant) insectensteek, acute paronychia.
Stadium 3: furunculaire myiasis (infestatie door vliegenlarven), persistant insect bite, scabiës, dermoid cyste, pyodermie (bij purulente laesie).
Stadium 4: locaal gangreen, acrolentigineus melanoom.
De diagnose wordt gesteld door een combinatie van klinisch beeld, beloop, en anamnese (recent in buitenland geweest in endemische gebieden). Eventueel aanvullend onderzoek: dermatoscopie (soms is lozing van eieren hierbij waarneembaar).
In alle gevallen de vlo / vlooien verwijderen. In de tropen wordt de vlo er meestal met een (steriele) naald uitgepeuterd, eventueel na reinigen met alcohol of ether (doodt de vlo). Om de vlo er netjes uit te krijgen zonder resten achter te laten is het eigenlijk nodig om de opening iets te vergroten. Bij aanwezigheid van meer faciliteiten kan men dat doen (zonodig na lokale anaesthesie) door de opening te omboren met een 4 mm biopteur of te vergroten met een of meer mes sneetjes. Daarna de vlo verwijderen met pincet en/of kleine curette. Goed reinigen en eventueel nabehandelen met lokale antiseptica (b.v. flammazinezalf of betadine jodiumzalf) om secundaire infectie te voorkomen. Check tetanus vaccinatie status, zonodig revaccineren (zie onder tetanus).
R/ Stromectol (ivermectine tab 3 mg), 200 microg/kg lichaamsgewicht eenmalig (overeenkomend met 15-24 kg 3 mg, 25-35 kg 6 mg, 36-50 kg 9 mg, 51-65 kg 12 mg, 66-79 kg 15 mg, vanaf 80 kg 18 mg). Bij multipele lesies.
R/ Ambilhar (niridazole, Ciba Geigy, te importeren op artsenverklaring) 30 mg/kg. Bij multipele lesies.
Voorlichting aan toeristen over het bestaan van de aandoening en advies om afgesloten schoeisel te dragen in endemische gebieden.
The host fish is a sheepshead (Archosargus probatocephalus)./
Sheepshead fish have teeth that look almost human.
The picture IS of a parasitic isopod that does effectively replace a fish’s tongueThe parasite replaces the fish’s tongue by attaching its own body to the muscles of the tongue stub.
The fish is able to use the parasite just like a normal tongue.
It appears that the parasite does not cause any other damage to the host fish.
… This is the only known case of a parasite functionally replacing a host organ.
Lintwormen zijn lintvormig, meestal wit of geelachtig en verdeeld in korte segmenten, proglottiden, die kort en breed of smal en lang zijn. Een volwassen lintworm bestaat uit een aantal proglottiden die samen bij sommige soorten wel 10 meter lang kunnen worden (sommige 30 m). Gedurende het hele leven van de lintworm worden er nieuwe proglottiden bijgemaakt, meestal vlak achter de scolex. Iedere proglottide groeit zodoende verder van de scolex af naarmate er meer jongere proglottiden bijgemaakt worden. De kop hecht zich doorgaans aan de darmwand. Onder de kop bevindt zich de halsstreek waarin de proglottiden zich vormen, die vrijwel geheel in beslag worden genomen door ovaria. Aangezien de lintworm tweeslachtig is, bevatten de proglottiden ook de mannelijke reproductieorganen. Er treedt zelfbevruchting op, zodat een volgroeide proglottide een groot aantal eitjes bevat. Na loskoppeling worden de proglottiden mee afgegeven aan de feces.
De twee meest voorkomende soorten bij de mens:
- varkenslintworm (Taenia solium)
- runderlintworm (Taenia saginata)’.
De varkenslintworm komt in westerse en islamitische landen bij mensen maar zelden voor. In West-Europa wordt de varkenslintworm als verdwenen beschouwd.
In West-Europese landen komt de runderlintworm in sommige landen nog veelvuldig voor, zoals in België (ca. 13.000 behandelingen per jaar), Nederland (ca. 20.000 behandelingen) en Duitsland (ca. 80.000 behandelingen). In andere landen, zoals Denemarken (1.000 behandelingen) is ook de runderlintworm een zeldzaamheid.
Voorkomende soorten bij dieren:
- kattenlintworm (Taenia taeniaeformis);
- hondenlintworm (Dipylidium caninum);
- vislintworm (Diphyllobothrium latum).
Canine Tapeworm Scolex//The proglottids pass through the digestive tract of the primary host and are eliminated with feces. Intermediate hosts (generally prey animals) ingest the larval forms when grazing on contaminated grass. Once ingested, the larvae emerge in the digestive tract where they burrow through the intestinal wall into a blood vessel and are carried to muscle tissue or some other organ tissue (various species of tapeworms select different tissues as destinations for the larvae). The period during which the larvae are encysted in the tissue of the intermediate host is known as the cysticercus, or bladder worm, stage.
Lintwormen hebben meestal een ingewikkelde levensloop waarbij 2 of soms nog meer gastheren betrokken zijn: de lintworm moet voor zijn ontwikkeling in verschillende dieren verblijven. De lintworm in de darm legt eitjes in enorme aantallen, die in de ontlasting naar buiten komen en door andere dieren (b.v. vee) worden opgegeten als de mest op planten terechtkomt. In deze tweede gastheer ontwikkelt zich dan geen lintworm maar een lintwormcyste: een holte in een orgaan, van binnen besmet met lintwormkoppen. Wordt de koe nu opgegeten zonder het vlees eerst goed te koken dan ontstaat in de darm van de eter weer de lange platte gelede vorm van de lintworm.
Kattenlintwormen hebben een cyclus waarin kattenvlooien als tussengastheer optreden. Veel prooidierpredatorsystemen hebben samen op deze manier lintwormen. De brede vislintworm Diphyllobothrium latum is een lintworm die mensen en vissen als gastheer heeft. De mens is in veel gevallen een toevallige gastheer. Verspreiding van menselijke lintwormen is zeldzaam omdat menselijke ontlasting in de westerse landen niet meer in de velden wordt gedeponeerd. Een gevaarlijke soort is de vossenlintworm (Echinococcus multilocularis), die voor de mens levensgevaarlijk kan zijn.
Dat mensen door een lintworm zouden vermageren, is een fabeltje; behalve wat vage maag-darmklachten merkt men het over het algemeen helemaal niet, behalve als de proglottiden van de worm met de ontlasting naar buiten komen.
De lintwormcysten zijn gevaarlijker, vooral als ze in de hersenen zitten. Andere voorkeursplaatsen zijn longen en lever. Op de Balkan worden dergelijke cysten nog wel eens waargenomen; in Nederland zijn ze een zeldzaamheid. Bij operatieve behandeling moet er voor worden gewaakt dat de cysten niet op zo’n manier stuk gaan dat de inhoud zich door het lichaam kan verspreiden, bijvoorbeeld via de bloedsomloop of in de vrije buikholte: dit kan wel eens hevige allergische reacties tot gevolg hebben.
Er zijn krachtige wormendodende middelen, zoals praziquantel, niclosamide en mebendazol die tegen de darmwormen meestal zeer effectief zijn; behandeling van de cysten is wel eens complexer, vooral als ze groot zijn of op riskante plaatsen zitten.