CLASSIFICATION OF SPIRORBIS

PHYLUM :- ANNELIDA (Metamerically segmented, coelomate and laterally symmetrical. )

CLASS :- POLYCHAETA (Many setae, clitellum absent. )

ORDER :- SEDENTARIA  (Tubicolous, sedentary and proboscis not-protrusible, without jaws or teeth.)

GENUS :- Spirorbis

GEOGRAPHICAL DISTRIBUTION

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

HABIT AND HABITAT

  • 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

SPIRORBIS

GENERAL CHARACTERSTICS 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.
SPIRORBIS

SPECIAL FEATURES

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

IDENTIFICATION

  • The animal contains pinnately branched tentacles and all above characters and hence it is Spirorbis.

SPIRORBIS
SPIRORBIS
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