Rhabdopleura belongs to the class Pterobranchia and represents one of the simplest living hemichordates. It lives in colonies on hard marine substrates and secretes delicate tubes, called coenecia, in which individual zooids reside. Each zooid extends its tentaculated arms to filter feed, capturing suspended particles from the surrounding water. Because it shares important features with ancient graptolites, Rhabdopleura helps scientists understand early deuterostome evolution and the origins of chordate traits.
Classification of Rhabdopleura
- Phylum :- Hemichordata (Marine, enterocoelous coelomate. Notochord confined to head region)
- Class :- Pterobranchia (Small hemichordates with encased body. V-shaped intestine.)
- Order :- Rhabdopleurida (Colonial, no gill-slits; 1 gonad)
- Genus :- Rhabdopleura
Geographical distribution of Rhabdopleura
- Researchers mainly find it in the Southern Hemisphere, and it is especially reported from the coasts of Norway and Ireland.
Habit and Habitat
It is a marine and colonial hemichordate, found 5 to 6 meters deep. The colony forms on hard substrata and also associates with mollusc shells, bryozoans, and tunicates.
Characteristics of Rhabdopleura
- Colony consists of zooids enclosed into erect tubes which are much more elongated than zooids.
- Colony contains erect coenoecium extended zooids, contractile stalk, decumbent coenoecium, retracted zooids, pectocaulus and young buds.
- Each zooid is composed of stalk, trunk sac, oral lamella, pigment stripe, cephalic shield, arms and tentacles.
- There is a lophophore with one pair of arms, one gonad, but without gill-slits. Alimentary canal is V-shaped.
- Most of the zooids are sterile, but male and female specimens may be observe.
- Sexes united.
- Development includes a free-swimming larva.
- Zooids are formed by budding, but the buds do not break off from the stolon and remain permanently attached to form a colony.
Special features
This colonial hemichordate forms organically connected individuals, and each new individual develops through sexual budding from an existing one.
Identification
Since the specimen contains extended zooids and all above features, hence it is Rhabdopleura.