Peripatus

This article is about the genus Peripatus. For the velvet worms as a whole, also known as peripatus, see Onychophora.
Peripatus
Scientific classification
Kingdom: Animalia
Phylum: Onychophora
Class: Udeonychophora
Order: Euonychophora
Family: Peripatidae
Genus: Peripatus
Guilding, 1826
Species

see text

Peripatus is one genus of Onychophora (velvet worms). The name peripatus (unitalicized) is also used to refer to the Onychophora as a whole, although this group comprises at least 48 other genera besides Peripatus.

Discovery

The genus Peripatus was described and named by Lansdown Guilding, a clergyman living in the volcanic Caribbean island of St Vincent who studied the natural history of the island. Further early studies were made by Arthur Dendy in Victoria, Australia.[1] Peripatus was the first genus of Onychophora to be scientifically described, in 1826.

Distribution

Peripatus is native to the South American region.[2] Other genera of onycophoran are found in Africa, Asia, Australia and New Zealand, but none are known in Europe or Antarctica.

Anatomy

Tentacled head of the "living fossil" Peripatus ater

Peripatus resembles a caterpillar, with its many pairs of legs, while its structure has similarities to both arthropods, but it also has many similarities to annelids, as well as some special features all of its own. The discoverer of the genus, Guilding, described it as a "leg-bearing slug".[2]

Peripatus shows no external segmentation; the legs are not jointed like arthropod legs, although they possess arthropod-like claws. The outer covering of the body is a cuticle covered in unique microscopic projections known as papillae. These papillae give Peripatus its velvety texture. The body is composed of segments like those of annelids, with segmentally arranged nephridia. The eyes are similar to those of annelids.[3]

Like other velvet worms, Peripatus has been called a living fossil, because the living members appear similar to fossil species as much as 570 million years old, and because Onychophora is transitional between the Arthropoda (including crustaceans and insects) and primitive Ecdysozoa such as tardigrades, priapulids and nematodes.[3]

Physiology and ecology

Peripatus is a nocturnal carnivore. It respires through tracheae, as arthropods do. In Peripatus the tracheae, of which there are some 2000, consist of short, simple, unbranched tubes, that completely lack the elaborate closing mechanisms of typical arthropods and thereby render it prone to dehydration. Antennae are present on the head. Excretion is through nephridia, which are found in each of the legs.

Peripatus feeds by trapping its prey (mostly small insects) in a white, sticky fluid it ejects from two antennae near its head. The fluid hardens on contact with the air immobilizing the prey. Peripatus then chews a hole in its prey's exoskeleton with its mandibles (which move independently of each other), injects digestive enzymes, and begins sucking out its prey's pre-digested innards.

Species

Peripatus belongs to the family Peripatidae, the viviparous onycophorans with a placenta or a yolked egg which develops inside the body; the other family of onychophorans, the Peripatopsidae, are oviparous or at least lack a placenta.[3]

Species of Peripatus include:

References

  1. ↑ Smith, Brian J., (1981) Arthur (1865–1925), Australian Dictionary of Biography, Volume 8, MUP.
  2. 1 2 Trewick, Steve; Morgan-Richards, Mary (2014). NZ Wildlife. Auckland: Penguin. pp. 171–178. ISBN 978-0-143-56889-6.
  3. 1 2 3 Ghiselin, Michael T. (1984). Eldredge, N.; et al., eds. "Living Fossils" (PDF). Peripatus as a Living Fossil. Springer-Verlag. pp. 214–217. Retrieved 2013-05-21.
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