Onychophora!

Dear Antboy,

My favorite animal is the tiger, but my second favorite animals are velvet worms! I was wondering, do you ever see them in Panama? Also, what do they eat? And are they really made of velvet?

Thanks for answering my questions!
Completely Fictional Reader

Dear Completely Fictional Reader –

Wow, you sure do have an impressive knowledge of obscure invertebrate phyla! While tigers are found only in Asia, I am happy to report that you can in fact find velvet worms here in Panama. While they’re pretty rare, by shocking coincidence my friend Jon just brought me one from the leaf litter in the forest yesterday!  Here’s a shot of it hanging off my desk in the lab:

Velvet worms are super-cool – they’re not really worms, and are instead in their own phylum, Onychophora. They have characteristics of both worms (Phylum Annelida) and arthropods (Phylum Arthropoda – this phylum is where you find insects and spiders and centipedes as well as crabs and other crustaceans). Onychophora is Latin for “claw-bearer”, and if you look closely at the ends of their “legs” you can see a tiny little claw there:

You may need to click on the picture and look at it full size on my Flickr page to really see the claws – they’re tiny. You may have also noticed those quotation marks around the word “legs”, and that’s because they’re not really true legs. They have no joints and are filled with fluid, relying on internal fluid pressure to maintain their shape. When velvet worms move, they move their stump feet by lengthening or contracting their body near that foot, kind of like how earthworms move.

As for what they eat, they’re predators! They eat insects, but they’re neither very fast nor can they fly, which would seem to make them somewhat unsuited for the task of eating very mobile insects, but they have a trick up their, uh, sleeve. They have slime glands in their head that can spray sticky clear slime over nearby insects, trapping them and preventing them from getting away while the velvet worm eats them slowly.

Finally, as for whether they’re made of velvet: no, no they’re not. However, they do have a velvety appearance from a distance thanks to their being covered in tiny little cone-shaped bumps called papillae, which have scales on them.

Thanks for the great questions, Person I Totally Made Up! If you want to read more about onychophorans, they have a surprisingly detailed Wikipedia page.