PERIPATUS – a ‘missing link’ unchanged for 500 million years

Environmental News Issue 28 Winter 2011 

The New Zealand peripatus are secretive, caterpillar-like animals, with soft, unsegmented body, velvety in appearance. They are 2.0-8.0 cm in length, slow-moving, with 13-16 pairs of soft stumpy legs.

Peripatus are usually coloured in dull shades of blue, green, grey or brown. Several New Zealand species are more brightly coloured, for example, Peripatoides indigo from the Nelson region is indigo-blue. The head bears a pair of large antennae and a pair of small oral papillae. Two tiny dark beady eyes are located near the bases of antennae. The name “peripatus” originates from Greek “peripatein” – “to walk around”, as these animals do with determination on their many stumpy legs.

Peripatus are voracious predators and feed on soil and litter arthropods (beetle larvae, crickets, spiders, termites, isopods, etc.), even on animals larger than themselves. Peripatus hunts by stalking the prey and immobilizing it with the transparent glue-like substance, which is squirted from the openings beside the mouth. This glue is extremely sticky, and soon entangles the prey. Peripatus then approaches and bites the prey, injecting it with digestive saliva; it can then suck out the liquified body tissues. Velvet worms themselves can be preyed upon by birds, lizards, large arthropods, and possibly rodents, although few observations of predation exist.

Similar to insects, peripatus breathe atmospheric air, which enters the body through spiracles – tiny openings in the body cuticle. Unlike insects, however, velvet worms cannot open or close the spiracles at will – the spiracles are always open, making these animals extremely vulnerable to dessication. The inability to control water loss restricts peripatus to damp, humid habitats.