Peripatus
Velvet worm
Introduction
It is a nocturnal, carnivorous animal found in damp places like crevices of rocks, bark, and leaf litter. It is famously known as a connecting link between Annelida and Arthropoda, exhibiting characters of both phyla.
Size & Structure
Size: Small body ranging from 2 cm to 15 cm in length.
Shape: Worm-like, cylindrical, and caterpillar-like body with unjointed legs (lobopods).
Colour: Dark grey, brown, or reddish, matching the soil or leaf litter.
Special external features: Skin has a velvety texture due to numerous minute papillae; head bears a pair of antennae and oral papillae.
General Features
- Coelom
- Coelomate (Hemocoel)
- Body plan
- Tube within a tube body plan (Protostomous)
- Germ layer
- Triploblastic
- Metamerism
- Superficial segmentation (Internal segmentation present)
- Body symmetry
- Bilateral symmetry
- Fertilization
- Internal fertilization
- Digestion type
- Complete (Extracellular digestion)
- Nervous system
- Ladder-like nervous system (Primitive)
- Excretory organ
- Nephridia (Segmentally arranged)
- Body temperature
- Poikilothermic
- Circulatory type
- Open type
- Development type
- Direct development (Mostly viviparous)
- Respiratory type
- Tracheal system (Tracheae open through diffused spiracles)
- Mode of excretion
- Uricotelism
- Circulation system
- Open (Haemolymph flows in sinuses)
- Skeleton structure
- Exoskeleton (Thin, non-chitinous cuticle)
- Level of Organisation
- Organ-system level of organisation
- Regulation of Osmosis
- Osmoregulator (Weak, restricted to moist habitats)
Ecology
Acts as a predator, feeding on small invertebrates like termites, beetles, and snails.
Serves as a prey for larger predators such as birds, lizards, and spiders.
Functions as an indicator of a healthy, moist forest ecosystem.
Economic Importance
Scientific Importance: Vital evolutionary evidence as a connecting link between Annelida and Arthropoda.
Research: Studied for its unique projectile slime mechanism (bio-adhesives).
Biodiversity: Represents an ancient lineage unchanged for millions of years (Living Fossil).