Velvet Worms

Velvet Worms, (Peripatus juanensis), Information compiled by Victor M. Cuevas, EYNF Biological Scientist

Photo from:  Father Sanchez Website of West Indian Natural History

General Notes

Often described as living fossils by biologists at the turn of the century, the Velvet Worm, Peripatus remains one of the most perplexing curiosities in the animal world and was and still remains the subject of much debate and controversy between biologists who study these curious animals.

This organism, that looks like a slug with legs, belongs to the Onychophora phyla, a small group of animals with many similarities between true worms (annelids) and invertebrates with segmented body (arthropods).  Onychophora is a very ancient phylum, and apparently have not suffered changes since the cambric era. Only 90 living species are known worldwide. Most of the members of this group prefer humid environments, like tropical rain forests.

Description

Invertebrate with soft body (~15-70 mm in length) velvety skin and paired unsegmented legs.  Although wormlike appearance and having a segmented body, the Peripatus have legs which move in similar fashion to the eyes of a snail and are able to be extended by variations in internal blood pressure.  It breathes by a system opening along the sides of its body known as tracheae, and so shares a breathing system similar to insects.

Natural History

Velvet Worms date back 400 millions years and may be a missing link between the Arthropods (Insects and Crustaceans) and Annelids (soft bodied segmented worms, including earthworms).

Shy creatures, able to hide in incredible tight crevices, these velvet worms are rarely seen in their natural habitat but could be found in leaf litter, earthen tunnels and foliage, under stones, and in fallen trunks.

Their main requirement is a dark and damp place, where they can spend the days inactive and hunt at night.  Their prey are small invertebrates, isopods, termites and small mollusks.  They shoot an adhesive liquid from a receptacle located near their mouth.  When the adhesive dries, after few seconds, the prey gets stuck to the ground and cannot escape.  Then the velvet worm approach it prey with it mandibles and pokes a hole in the prey and secretes digestives juices.  Finally, it applies it mouth to the wound and sucks out the food from the victim.  This sticky glue is also used as a defense against their own predators.

Distribution

Restricted to Rain Forest regions of South America, Africa, Australia, The Caribbean, Malaysia and Oceania.

Look for it in the EYNF

Rare to find due to its secret habits, this organism may be found by coincidence when it microhabitat get exposed.

This family, Onychophora, is represented in Tabonuco Forest by a species of Peripatus that is occasionally found foraging on moss- and algae covered rocks on the forest floor prey immobilization is accomplished by directing and adhesive spray at the victim, large prey such as crickets and roaches may be captured by this strategy (Reagan and Waide, 1996).

It was occasionally observed when preparing Palo Colorado (Cyrilla racemiflora) wood material for Puerto Rican Parrot nests.  Natural cavities bottom material and fallen branches with dead wood were collected for preparation.  When cleaning the collected material, Peripatus individuals were often found.