CLASSIFICATION OF PERIPATUS OR VELVET WORM
KINGDOM :- ANIMALIA (Multicellular eukaryotic organisms)
PHYLUM :- ARTHROPODA (Jointed appendages.)
CLASS :- ONYCHOPHORA (Primitive arthropods with unjointed legs and annelidan set up.)
ORDER :- EUONYCHOPHORA
FAMILY :- PERIPATIDAE
GENUS :- Peripatus
It has a discontinuous distribution. Found in damp forests of Africa, Malaysia, Australia, South America and New Zealand.
HABIT AND HABITAT
Peripatus is a nocturnal carnivorous animal, living in rock crevices, under bark of trees, stones and moist places.
GENERAL CHARACTERSTICS OF PERIPATUS OR VELVET WORM
- It is referred as living fossil or velvet worm.
- Body of the animal is cylindrical and elongated caterpillar like and measuring 4 to 6 cm in length.
- Outer covering of the body is thin velvety, chitinous showing transverse wrinkles, numerous small papillae or tubercles.
- Anterior end is marked by preantennae and ventral mouth and posterior end by anus.
- There is a head of three segments which is not clearly separate form the body.
- Post-oral segments of the head bear pair of hooked jaws, a pair of oral papillae, a pair of simple eyes and a pair of segmented antennae. It feeds on insects which they catch by means of slime ejected from their oral papillae.
- There are about, fifteen pairs of walking legs. Each leg is unjointed but is ringed by ridges having tubercles and terminates in a foot, which bears two curved claws and three distinct tubercles.
- There is a tracheal system (for respiration) with spiracles scattered irregularly over the body surface. Excretion nephridial. Sexes separate.
- Crural glands are absent and genital pore is posterior. Mostly viviparous, but some may show oviparity.
- Peripatus is supposed to be the connecting link between Annelida and Arthropoda.
Peripatus was first described in 1825 and was classified with the molluscs due to its slug-like appearance. Grube (1874) kept it under Annelida and coined the name Onychophora. Burmeister (1856) placed the group between annelids and arthropods and Moseley (1874) finally demonstrated its relationship with arthropods by showing the presence of trachea. Peripatus is zoologically very interesting, because it exhibits both arthropod and annelid characters as under :
Annelidian characters : The vermifonn body, dermo-muscular body wall, simple eyes, unjointed, hollow stumpy appendages on annelidan pattern.
Arthropodal characters : Antennae, chitin in cuticle, haemocoel, tracheae, general structure, development and peculiar salivary glands like arthropods.
The animal contains pre-antennae, 2 clawed appendages and above features, hence it is Peripatus.