Serpulidae (original) (raw)

About Family Serpulidae polychaetes in New Zealand.

How to recognise the family:

Includes Spirorbinae, formerly Spirorbidae. The serpulid calcareous tube, hard and long-lasting, makes this family one of the most noticeable polychaete groups, and one that is also economically a problem worldwide when after colonial settlement large masses of tubing build up as 'fouling' on boat hulls or inside industrial pipes. The serpulid body is similar to that of sabellids with its thoracic and abdominal regions and crown of radioles, but more specialised. Serpulids never leave their tubes and unlike sabellids the crown used for filter-feeding is rarely cast off or lost in handling. Instead it is retracted into the tube in an instant and the tube mouth blocked by an operculum, here a modified radiole bearing an ornamented plug at the end. The serpulid thorax has a cloak-like thoracic membrane, the free edge of which runs from a frilly collar round the base of the radioles down the dorsal surface of the thoracic chaetigers (usually seven in number) and across the ventral surface of the last thoracic segment. The pygidium usually lacks ornamentation.

The spirorbine sabellids are small, coiled, filter-feeding worms, the asymmetrical inhabitants of spiral, calcareous tubes. One side of the spiral is cemented flatly against the material the worms have chosen to settle on as larvae. Previously regarded as warranting family status, currently spirorbines are more usually included in the serpulids. They occur on many hard surfaces, but are conspicuous either scattered loosely or in dense aggregations on the underside of stable rocks in intertidal pools, or spotted like white dots across the fronds of large algae such as Macrocystis kelp.

An examination of the operculum and the tube is the easiest way to begin to identify serpulids, but a look at any group of specimens will reveal that the ornamentations on these structures can have substantial natural variation. The morphology and disposition of chaetae must also be examined, especially the microscopic detail of the collar chaetae, which are the capillary notochaetae of the first chaetiger, somewhat forwardly displaced from the following sets of chaetae. There are no neurochaetal uncini on this first chaetiger. Adult size: Variable, up to 150 mm long or more for Protula sp., but most species are in the range of 10-40 mm length. In spirorbines the diameter of the entire coiled tube rarely exceeds 5 mm.

How to recognise the New Zealand genera:

See species notes.

Quick pick shore species:

A number of large and small serpulids occur in New Zealand and it is surprising they have not received more taxonomic attention. The two most conspicuous of the large species that occur in coral-like aggregations are Spirobranchus cariniferus (Gray, 1843) (better known as Pomatoceros caeruleus (Schmarda, 1861)) characterised by a near-flat operculum, dark blue body, and blue-black striped tube with single longitudinal keel, and the much larger Galeolaria hystrix (Morch, 1863), characterised by an operculum with dense palisades of calcareous white spines, a red body, and pink tube with double keel. A recent immigrant into New Zealand is Ficopomatus enigmaticus (Fauvel, 1923), in which the operculum has black spines and the round white tube has flared rings at intervals.

Spirorbines have additional specialisations including various means of brooding larvae within the tube. These reproductive differences are used in identification. In Pileolaria and Amplaria the embryos are found in the operculum, whereas in Protolaeospira and Romanchella, they are attached to a thoracic stalk. In most genera known in New Zealand the tube coils to the left (sinistral) as it spirals inwards, with the aperture facing clockwise (turning right as it grows), whereas in Janua the tube coils to the right (dextral) with the aperture facing anticlockwise. However this character cannot be absolutely relied upon as in some species coiling can be in either direction. The ornamentation of the tube has also proved to be an unreliable character for species separation. As in the serpulids and sabellids, the uncini are neuropodial in the thoracic chaetigers, and swap position with the capillaries to occupy the notopodia in the abdominal chaetigers. There are three to five thoracic chaetigers, and the anterior body is distorted in a twist so that uncini always tend to face the concave side of the tube.

There were over 24 New Zealand spirorbine species when first surveyed in 1977, probably not a complete tally, and as spirorbids also have the capacity to introduce themselves via shipping, some further foreign imports may have arrived in the intervening years. The genera Amplaria, Janua, Metalaeospira, Paralaeospira, Pileolaria, Protolaeospira, Romanchella and Spirorbis were reported at that time.

Possible misidentifications:

Serpulidae with their calcareous tubes are not confusable with any other family, and spirorbines are very characteristic in morphology.

Distributions, lifestyle, and habitat:

Intertidal to deep sea throughout New Zealand. Spirorbines are intertidal and subtidal to abyssal, but most species are restricted to coastal waters. Ficopomatus enigmaticus as yet occurs in only a few estuaries in the northern North Island. Spirobranchus cariniferus is endemic and absent from the Chatham Islands.

Serpulids may occur on all firm surfaces underwater. Spirobranchus caeruleus is a zoning intertidal rocky shore species, also found out on the soft sediments of harbour flats on isolated stones and dead shell. Galeolaria hystrix is found subtidally on rock and other firm surfaces. Although isolated individuals can be found, most often it is gregarious, and may occur in some deep sheltered localities in massive colonies that are up to several metres across and a metre or more in height. Ficopomatus enigmaticus occurs in characteristic low intertidal hummocks in brackish waters. Spirorbines occur cemented onto rock, shell, algae, bryozoans, crustacean carapaces, etc. Some spirorbine species are very selective as to their preferred habitat.

Abundance:

Common.

Taxonomic note:

The nomenclature of serpulids is confused, with many synonyms of genera and species, and the expectation of numerous occurrences of unrecognised species lumped under one name. However, some species are widely distributed due to transport by shipping.

A subtidal species recognised by its opercular structure of a stacked series of calcareous plates has been known as Spirobranchus latiscapus (Marenseller, 1885), though this name may be incorrect. The name Pomatoceros terraenovae Benham, 1927 has probably been misapplied to a solitary Pomatoceros species that has a pink tube_._ A possible further Pomatoceros species is very common in depths of 100 metres or more, and has a characteristically curved, pink tube of triangular section and a flat operculum. Protula bispiralis (Savigny, 1820) is a solitary species that lacks an operculum. It can be extremely large, and has a wide thoracic membrane, spiralled radioles, and a very thick-walled, smooth round white tube. Neovermilia sphaeropomatus (Benham, 1927) has a perfectly spherical operculum on a slender stalk.

The small serpulids include several Serpula species with flower-like opercular funnel, amongst which is Serpula maorica (Benham, 1927), and various Hydroides species with a second tier of spines above the funnel. Members of these genera are amongst the commonest ship-fouling serpulids and in New Zealand probably include some previously foreign species that have arrived as hitchhikers on ship hulls. Salmacina species form colonies of delicate thin tubes interwoven into masses, by both aggregation and asexual budding. Salmacina have no operculum and few radioles. Ditrupa species live in sediment, have tusk-like tubes and have frequently been mistaken for scaphopod molluscs of the genus Dentalium. The New Zealand form may be Ditrupa gracillima Grube, 1878.

References:

(Augener 1926: p270-278), (Baird 1865: p10-14, 21-22, P1.2, 2.9-10), (Benham 1927: p147, 153-154, 160-167, P4-5), (Day 1975: p204-205, f4.h-m), (Day & Hutchings 1979: p142-149), (Dew 1959: p19-56, f1-21), (ten Hove 1984: p181-196, f1-7), (ten Hove & Jansen-Jacobs 1984: p143-180, f1-12), (ten Hove & Smith 1990: p101-118, f1-62), (Knox 1949: p1-127), (Knox 1951b: p75-76), (Knox 1953: p205), (McIntosh 1885: p514-515, 520-522, P31a.21-22,26-28, 54.4, 55.3-4), (Morton & Miller 1973: p127, f24.a, 47, P4.a), (Read & Gordon 1991: p269-273, f1), (Schmarda 1861: p29-30, P21.178), (Straughan 1967: p201-261, f1-16), (Whitley 1966: p103-113, P52-56). Spirorbines: (Day & Hutchings 1979: p149-151), (Knight-Jones 1978: p234-240), (Knight-Jones & Fordy 1979: p119-138, f1-108), (Knight-Jones & Knight-Jones 1984: p196-210, f1-7), (Knight-Jones & Knight-Jones 1994: p77, 91-92), (Vine 1977: p1-68, f1-35).
(Full citations at Family pages literature cited list.)