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Sunday, February 19, 2012

Creature Feature: Aysheaia.

Soft-bodied invertebrates do not preserve well in the fossil record. Their squishy bits rot away, leaving us with very little to guide us in regards to ancient invertebrate life. When we do find them, however, they usually freak us out.




Aysheaia are no exception. Another Cambrian arthropod from the infamous Burgess Shale, Aysheaia were strange, caterpillar-like creatures 1-6 cm long. They lived in the Cambrian seas right alongside Hallucigenia. Yes, your nightmares now have company.

Aysheaia resembled caterpillars or maggots with ten pairs of legs. If that image is not sufficient to freak you out, each of these pudgy legs had two needles sticking out of it. Finally, there were even more spikes around its mouth. If you're thinking that it resembles a parsnip left in the fridge for so long that it grew legs, you're on the right track.

 

Aysheaia were probably sponge eaters. All fossils of them have been found near sponges. There is not much nutritious about sponges, so it must have needed to spend a lot of time around them. The sponges may also have been providing he caterpillar-worms with protection. It would presumably wander across the seabeds in search of sponges...but that's all we know.

Unlike several other members of the Cambrian seabed, Aysheaia have modern relatives. Velvet worms are one of the oldest types of land-dwelling creatures ever. They are somewhere between water bears and arthropods. Despite being related to two other ubiquitous families, however,velvet worms are limited only to certain tropical regions of the world. More on them tomorrow!

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