Family CAPITELLIDAE

Capitella sp.

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Family CAPITELLIDAE

Compiler and date details

Jan 2011 - P. Hutchings & M. Yerman, Australian Museum, Sydney, New South Wales, Australia

11 July 2003

Introduction

Capitellids resemble terrestrial earthworms. They have a pointed or rounded head that lacks appendages, and a long cylindrical body. Parapodia are poorly developed and chaetae appear to arise directly from the body wall. They are often reddish in colour and may be tightly coiled on the collecting sieve.

Capitellids may be extremely abundant in muddy sediments; some are tolerant of polluted conditions and may be useful as pollution indicators. Some species of capitellids that have been found in contaminated sediments can build up dense populations very quickly, but these populations may then crash. Capitellids are deposit feeders and consume micro-organisms adhering to the mud particles, swallowing the mud using an eversible proboscis.

Figures of ~18 genera and ~37 species were given by Beesley et al. (2000: App. 1) for representation of the family in Australian waters, and 47 genera and 160 species worldwide. Since Beesley (2000) the number of species reproted for Australia has been updated to over 50, of which only 19 are described, from 9 genera.

See Hutchings (2000) for detailed family treatment.

Database Notes

proof read against Day & Hutchings 1979 by RW;
Hutchings & Murray 1984, Doyle 1991 and Warren, Hutchings & Doyle 1994 updated by RTJ
checked against DELTA CD 2003 by RTJ

Diagnosis

General features. Body shape vermiform; segments numerous (more than about 15); regionation present, comprising distinct thorax and abdomen; regions demarcated by major differences in chaetal types over body. Epidermis thick and rugose (anteriorly). Pygidium simple ring or cone, or plate-like (rarely). Pygidial appendages absent, or present; one pair of cirri, or single medial cirrus.
Head & head structures. Head discrete and compact, dorsal to mouth. Prostomium bluntly conical to trapezoidal (narrow end anteriorly). Eyes absent, or present; one pair, or multiple; situated on prostomium; without lenses. Palps absent. Nuchal organs indistinct paired dorsolateral patches. Peristomial ring single (may sometimes appear double in fixed specimens).
Pharynx & pharyngeal apparatus. Foregut a non-muscular axial proboscis.
Body segments & parapodia. First segment chaetigerous. First chaetiger with notochaetae only, or with neurochaetae only, or with both notochaetae and neurochaetae. Parapodia biramous with parapodial lobes absent or low; notopodial lobes low lateral ridges (tori) (posteriorly); neuropodial lobes low ridges (tori) (posteriorly). Lateral organs present. Dorsal cirri absent. Ventral cirri absent. Branchiae absent, or present (may be retractile); arise from parapodia, or arise from dorsum; occur on at least some chaetigerous segments; digitiform, or branching; lamellate.
Chaetae. Notochaetae present. Aciculae absent. Capillary chaetae present, or absent (rarely); hair-like; smooth. Spines absent, or present only in one or a few anterior chaetigers, or present only in posterior chaetigers (genital spines occur in chaetigers 8,9 in sexually mature individuals in a few genera; other genera have spines in the notopodia of pre-anal segments). Hooks present; with a distal hood; occur in many chaetigers in both rami (at least posteriorly).
Tube & burrow. Tube absent or unconsolidated, or membraneous. Burrow traces simple, or comprises interconnected galleries.

The above description was generated from: 'C.J. Glasby & K. Fauchald (2002 onwards). POLiKEY. An information system for polychaete families and higher taxa: Version 1: September 2002.'
(See ABRS website: Online Resources: Polikey, for Version 2, released June 2003)