Other animals of the same general type have now 

 been found living on every continent except Europe. 

 Each one may be referred to as a peripatus (spelled 

 without a capital), although the eighty-odd different 

 kinds are now placed in a dozen genera and two dif- 

 ferent famiHes. 



Wet forests conceal these animals, from within a 

 few feet of sea level to high in the Andes of South 

 America. Various kinds of peripatuses are found as 

 far north as Mexico and as far south as the Cape of 

 Good Hope. One kind in Panama and adjacent coun- 

 tries reaches a length of 5 inches and the diameter of 

 a lead pencil; it is Macroperipatus geciyi. Best known 

 of the velvet worms, however, are Peripatopsis ca- 

 pensh from South Africa and Peripatoides novae- 

 zealandiae from New Zealand. 



Creatures of this body form have been walking 

 the earth for at least five hundred million years. They 

 may well have been among the earliest animals to 

 creep out upon the land. Today's velvet worms are 

 all terrestrial, extremely retiring in habit, and seldom 

 seen except by naturalists who hunt them out. Per- 

 haps this is because the peripatus avoids air contain- 

 ing less than 90 per cent of full saturation with water 

 vapor. In so limiting themselves, the velvet worms 

 parade in the open only at night or during rains, 

 while the relative humidity is close to 100 per cent. 

 By day they take shelter in the ground, or under 

 stones and rotting logs, or between the leaf base of a 

 palm tree and the trunk. 



Every velvet worm has an amazing means of de- 

 fense. On each side of the thick-lipped sucking mouth 

 a small papilla marks the opening of a duct from 

 large salivary glands. From these glands the animal 

 can spit a blob of sticky secretion resembling clear 

 rubber cement. Within seconds the liquid becomes 

 opaque white and fairly firm. If a peripatus ejects its 

 special slime at an annoying ant or other small at- 

 tacker, the aim is usually excellent and the insect is 

 effectively restrained. 



Whether velvet worms use their salivary cement 



Fairy shrimps (Euhranchipus vernalifi) appear sud- 

 denly in meltwater ponds in springtime. They swim 

 about catching microscopic green plants as food, and 

 reproduce before migrant birds arrive or other poten- 

 tial enemies awake from hibernation. (Pennsylvania. 

 Ralph Buchsbaum) 



to subdue insects as prey is still questioned. Most 

 peripatuses appear to eat dead insects and worms 

 which they find as they explore among the leaf litter 

 and bark crevices. But in the southern hemisphere 

 some velvet worms live in termite nests, devouring 

 dead termites. Whether they occasionally take a live 

 termite has not been determined. 



In captivity, some individual velvet worms will ac- 

 cept bits of liver. Some will seize live termites, other 

 small insects, and woodlice. Most will feed readily 

 upon freshly-killed flies and grasshoppers, cock- 

 roaches, and crickets. Others refuse food of all kinds, 

 and within a few weeks die as a result of their hunger 

 strike. 



Occasionally a peripatus makes the mistake of 

 spitting on its own back. The slime hardens, affixed 

 firmly to the wrinkled, pebbled, water-repellent skin. 

 In a few days, however, the velvet worm frees itself 

 from the inflexible encumbrance by shedding the 

 outer layer of the skin. This ability to molt is one of 

 the ways in which a peripatus earns a place for itself 

 among the arthropods. Another feature assumed to 

 have similar meaning is the pair of bladelike jaws in 

 the mouth. And a velvet worm breathes in a manner 

 most like some of the centipedes, millipedes, and in- 

 sects — using branched air tubes (tracheae) admit- 

 ting air through openings on the surface of the body 

 to inner organs. 



Unlike that of typical arthropods, however, the 

 skin of a velvet worm never develops a rigid cuticle. 

 Molting tends to be by patches, rather than of a com- 

 plete body covering at a time. In this respect a peri- 

 patus seems more akin to some of the annelid worms. 

 Such resemblance extends to the excretory organs as 

 well, for each leg base of a velvet worm carries the 

 opening of a nephridium — the kind of organ serving 

 annelid worms in much the same way that the kidney 

 does a vertebrate animal. No other arthropod has 

 nephridia. 



Each peripatus is either a male or a female. Often 

 the sexes can be distinguished in that the males have 

 two or three fewer pairs of legs than the females. 

 Male velvet worms sometimes seem unaware of sex- 

 ual differences, for they may deposit a package of 

 sperm cells upon the back of another male almost as 

 readily as upon the body of a female. Only in the 

 latter instance, however, does the skin develop an 

 ulcer below the sperm packet and white cells from 

 the blood open a passage through the skin. In this 

 way the sperms are admitted into the body cavity, 

 where they can migrate directly to the ovaries. For as 

 much as a year, the arriving sperms may all be ab- 

 sorbed and used as nourishment for the developing 

 eggs. Then, with the eggs finally ready for fertiliza- 

 tion, another swarm of sperm cells can initiate the 

 steps whereby a fertilized egg grows into an embryo 

 and then a new individual. 



