| Palæos: |  |
Anomalocarida |
| INVERTEBRATES | Anomalocarida |
| Palæos: | |
Anomalocarida |
| INVERTEBRATES | Anomalocarida |
Anomalocaris canadensis was about 60 cm long, which may not seem much in today's terms but was huge relative to anything else around during the Cambrian (some specimens seem to have been even larger - up to a meter or more). For tens of millions of years this slow-moving swimmer dominated Cambrian seas. It had a pineapple-ring mouth (useful for slicing and dicing prey) and a pair of long spiky grasping appendages. It was originally believed to be three separate animals (the pineapple ring mouth was thought to be a jellyfish (Peytoia) - the large lobed body a sponge, & the grasping appendages the tail of a crustacean - that was the original "Anomalocaris"). Swimming was accomplished by means of undulations of fin-like appendages along the side of the body.
It is not know what phylum of organisms Anomalocaris belonged to. It is frequently lumped with arthropods, on the basis of its jointed body; however, other creatures like annelids have also evolved a segmented body). An alternative explanation is that it was a kind of aschelminth (pseudocoelomate worm), as indicated for example by its asymmetrical mouth. Another possibility is that it is a form transitional between lobopods and true arthropods. Without doubt it among the "molting animals", ( a group that includes many segmented animals). Its difference from modern organisms is a reminder, as are all the problematica, of the diversity of life, and the fact that the type of creatures around at present are only a fraction of the number and diversity that have ever lived.
There is a Scientific American article (and also I think a more in-depth article in Paleobiology) that mentions predation on trilobites, and has a photo of a trilobite with a big bite taken out of the side. Interestingly, trilobite eyes were apparently designed to give optimal upward facing vision - so as to detect something swimming at them from above. They would not have evolved such organs were there not a pressing biological need for them.
Anomalocaris has acquired something of a mystique rare among prehistoric invertebrates. Because of it's relative size and apparently carnivorous habits (although one fellow has suggested it only ate algae! something I find difficult to believe), it has become the T. rex of the Cambrian. You will find more hits for Anomalocaris on any decent search engine (e.g. Alta Vista) then u will for any other Cambrian creature
Other Cambrian creatures like Opabina and Sanctocaris were also probably predators, but at 3-4 inches are much smaller.
"The Emergence of Animals" by Mark A. S. McMenamin - which features
Anomalocaris on p.91 (the trilobite photo - an Olenellus robsonensis, is
on the facing page). Unfortunately I did not record the issue when
I photocopied the article - it is most probably late 80s, maybe 1987."
Whittington H.B. & Briggs D.E.G., "The Largest Cambrian Animal, Anomalocaris, Burgess Shale, British Columbia", Philosophical Transactions of the Royal Society, 1985, B 309, pp.569-609
