Spirorbis

Contents hide

1) Classification of Spirorbis

2) Habit and habitat of Spirorbis

3) Distribution

4) Comments of Spirorbis

5) Special features

6) Identification

Classification of Spirorbis

The genus Spirorbis contains tiny polychaete worms (2–5 mm; 0.079–0.197 in) that often have a white, coiled shell. The genus’s members inhabit stony shorelines’ lower littoral and sublittoral zones. Although some species of spirorbis worms dwell directly on rocks, shells, or other hard substrates, most species are linked to seaweeds. Although all pre-Bathonian (Middle Jurassic) spirorbins are now recognized to be microconchids, it was previously believed that Spirorbis had a fossil record dating back to the Early Paleozoic. The genus’s first members first appeared in the Miocene, however Oligocene discoveries are possibly conceivable.

Kingdom :- Animalia (Multicellular eukaryotic organisms)

Phylum :- Annelida (Segmented worms with true coelom and metamerism)

Class :- Polychaeta (Marine bristle worms with parapodia)

Order :- Sabellida (Tubicolous, sedentary and proboscis not-protrusible, without jaws or teeth)

Genus :- Spirorbis

Habit and habitat of Spirorbis

Spirorbis is minute, tubicolous, sedentary polychaete living in a small calcareous tube, coiled in a flat spiral manner which is incrusted on seaweeds, stones, shells and any hard calcareous object of the sea

Distribution

Commonly found in U.S.A., Long Island to Bay of Fundy and northwards.

Comments of Spirorbis

Animal measures about 3 mm in length and tube diameter is also nearly 3 mm.
Body is divided into anterior and posterior regions.
Anterior end is constituted by prostomium and peristomium.
Prostomium contains pinnately branched gills.
One of the gill filaments is enlarged to form stopper or operculum.
There are 9 greenish gill filaments.
Operculum is grooved on one side to serve as brood punch for the developing eggs.
Peristome is similar to other segments of the thorax, but it forms a collar which secretes the tube.
Abdominal segments are hermaphroditic.
The anterior abdominal segments produce eggs while posterior segments sperms.

Special features

It has long fossil history. It was abundantly found in Silurian Paleozoic and strata.

Identification

Since the specimen contains pinnately branched tentacles and all above characters and hence it is Spirorbis.

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