NIWA Guide to Polychaeta | Shore polychaetes | Pick shore group | Pick shore family | Shell polychaetes
Capitellidae Family Capitellidae (capitellid)
Scolecida (Annelida: Polychaeta)
About Family Capitellidae polychaetes in New Zealand.  
How to recognise the family: Thread-like sediment dwellers that live in unlined, rambling burrows and are considered to be relatively non-selective particle feeders. Capitellid worms are long, fragile, and difficult to collect intact. The capitellid body is weakly divided into a short anterior, so-called thoracic region of 8-21 plump segments and a long posterior abdomen of somewhat thinner segments. Capitellids have an open blood circulatory system without major vessels.There are no head appendages. The prostomium is conical to pointed. The first segment usually lacks chaetae, but not in Capitella. Parapodial lobes are no more than pads. The chaetae are capillaries in a limited number of anterior segments and thereafter hooded hooks, each with one main tooth and a transverse row of minute secondary teeth behind it. Adult size: Up to 50 mm long, and very thin.
How to recognise the New Zealand genera: The important generic-level characters are the number of anterior segments (9 in Capitella, 11 in Mediomastus, 12 in Heteromastus, Barantolla and Notomastus) and the number of capillary-bearing chaetigers (3-7 in Capitella, 4 in Mediomastus, 4-5 in Heteromastus, 6 in Barantolla, and 11 in Notomastus). However the thoracic-abdominal boundary may be difficult to determine and in juveniles there may be fewer segments with capillaries. Thus caution is needed in identifying individuals, although with enough specimens, as capitellids usually occur in large numbers, the issue should be resolvable.
Quick pick shore species: The up-curved pointed prostomium of Heteromastus filiformis (ClaparFde, 1864) is easily recognisable, as are its pairs of gill-like dorsal extensions on posterior segments. It also has a pygidial cirrus, otherwise lacking in most capitellids. However Barantolla is very similar to Heteromastus and a subtidal Barantolla species has recently been found which is distinctive for having only notochaetae on the first chaetiger. Mediomastus is also a very similar genus and is mentioned here as, although it has not been recorded from New Zealand, it may have been overlooked in the past, and is confusable with juveniles of Heteromastus spp.. Capitella males may have prominent enlarged notochaetal spines on chaetigers eight and nine. The well-known form previously believed to be one cosmopolitan species, Capitella capitata (Fabricius, 1780), has been shown to be a complex of numerous species. Most have yet to be scientifically named. There are at least two Capitella species in New Zealand. No rocky shore species.
Possible misidentifications: None
Distributions, lifestyle, and habitat: Mid-intertidal to continental shelf depths throughout New Zealand. Heteromastus filiformis and Capitella species occur throughout the world. Capitellids burrow deeply into muds and muddy sands, particularly in estuaries and harbours, and sometimes flourish in organically-enriched substrata. The surface sign consists of a tiny cone of black sediment pellets brought up from the anaerobic layers. Heteromastus filiformis is the most likely species to be encountered, followed by Capitella species.
Abundance: Common. Locally very dense around organic effluent discharges.
Taxonomic note: A much larger subtidal capitellid is a Notomastus sp. The validity of the similar and apparently endemic genus Capitellethus known only for Capitellethus dispar (Ehlers, 1907) is dubious but unresolved. Capitella has cryptic species.
References: (Eckelbarger & Grassle 1987: p62-76, f1-24), (Ehlers 1907: p24-25, f15-16), (Fauchald 1977: p31-36), (Grassle, Gelfman & Mills 1987: p77-88, f1-7), (Hutchings & Rainer 1982: p373-380), (Read 1983: p225), (Warren 1976: p195-209, f1-2, P1-4), (Warren, Hutchings & Doyle 1994: p227-256, f1-12), (Warren & Parker 1994: p299-306, f1-2).
(Full citations at Family pages literature cited list.)

Species in the guide: Rock Species: None for this family.
Sand Species: Capitella capitata | Heteromastus filiformis
Shell Species: None for this family.

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Last modified by G. Read, 25/07/2004    (dd/mm/yy)