Peripatus (Onchyphora)
The Phylum Onychophora are a very small group of terrestrial animals, commonly known as peripatus or ‘velvet worms’ from their velvety appearance.
This group has long been regarded as important in evolutionary biology due to their phylogenetic position, ancient history and Gondwanan distribution. Evolutionary relationships constructed using morphology and molecular data clearly show the Onychophora as a sister group to the Arthropods and a member of the Ecdysozoans.
They are truly archaic creatures, having scarcely changed appearance since 550 million years ago when present in the Cambrian Burgess Shale sediments where they lived in shallow marine environments.
Today, the phylum Onychophora consists of entirely terrestrial forms and is split into two families:
- the Peripatidae (found in the Antilles, Mexico, Central America, northern South America, equatorial West Africa, Assam, and Southeast Asia) and
- the Peripatopsidae (found in Chile, South Africa, West Irian, New Guinea, Australia, and New Zealand).
Present-day Onychophora are restricted to moist, dark microhabitats such as within and under rotten logs, leaf litter, under stones, and crevices in rocks or soil.
Peripatus are nocturnal predators which trap their prey using a sticky substance expelled from a pair of modified limbs, the oral papillae located on either side of the head.
Reproductive strategies within this group are surprisingly diverse. These include oviparity, ovoviviparity, viviparity with yolk-free eggs, and placental viviparity. Oviparity and ovoviviparity are the common reproductive strategies of the Peripatopsidae. Oviparous forms lay eggs singularly and possess an obvious ovipositor positioned between the last pair of legs, while ovoviviparous forms have eggs that hatch internally and give birth to live young.
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| Female P. novaezealandiae with newborn. Image - M. Heffer |
Worldwide estimate of species number within the Onychophora is difficult to ascertain as some taxonomic revisions are in progress.
The taxonomic status of New Zealand's Onychophora is also under review, although this website provides information on current recognised species, along with an location guide of Onychophora present throughout New Zealand.