''Syllis prolifera'' is a species of polychaete worm in the family

Syllidae Syllidae is a family of small to medium-sized polychaete worms. Syllids are distinguished from other polychaetes by the presence of a muscular region of the anterior digestive tract known as the ''proventricle''. Syllid worms range in size from ...

. It has a

cosmopolitan distribution In biogeography, cosmopolitan distribution is the term for the range of a taxon that extends across all or most of the world in appropriate habitats. Such a taxon, usually a species, is said to exhibit cosmopolitanism or cosmopolitism. The ext ...

. It was first described in 1852 by the Russian/German zoologist August David Krohn who gave it the name ''Syllis prolifera''.

Description

This small worm grows to a length of about . The two palps are widely separated and the eversible pharynx bears a large tooth near the rim but behind the pharyngeal opening. On the dorsal surface, long and short

cirri Giovanni Battista Cirri (1 October 1724 – 11 June 1808) was an Italian cellist and composer in the 18th century. Biography Cirri was born in Forlì in the Emilia-Romagna Region of Italy. He had his first musical training with his brother ...

alternate. The antennae and cirri have dark spots, but the general body colour is variable, being some shade of brown, grey or pink, sometimes with orange or pink speckling near the anterior end.

Distribution and habitat

''S. prolifera'' is found in the northeastern Atlantic Ocean and the Mediterranean Sea, as well as the northwestern Atlantic, the Caribbean Sea and the Gulf of Mexico, Mozambique and New Zealand. It is present from the lower shore down to the

sublittoral zone The neritic zone (or sublittoral zone) is the relatively shallow part of the ocean above the drop-off of the continental shelf, approximately in depth. From the point of view of marine biology it forms a relatively stable and well-illuminated ...

, on soft sediments of varying types and among seaweeds.

Life cycle

''S. prolifera'' is a "stolonate" worm and has an unusual life cycle. When the worm has reached a length of about forty segments, the posterior portion of the worm develops into a

stolon In biology, stolons (from Latin '' stolō'', genitive ''stolōnis'' – "branch"), also known as runners, are horizontal connections between organisms. They may be part of the organism, or of its skeleton; typically, animal stolons are external s ...

inside which the

gonad A gonad, sex gland, or reproductive gland is a mixed gland that produces the gametes and sex hormones of an organism. Female reproductive cells are egg cells, and male reproductive cells are sperm. The male gonad, the testicle, produces sper ...

s mature. The stolon is either female (pale orange) or male (whitish) and becomes a storage receptacle for the eggs or sperm. Breeding is regulated by the phases of the moon, and when the breeding period arrives, the stolon becomes detached and joins others to swarm in the water column, in a process known as " epitoky". Here the gametes are released and the stolon dies. Meanwhile, the parent worm remains on the seabed and starts to grow a new stolon which is ready for release some 28 days later. When fertilised, the eggs sink to the seabed. After about 48 hours they hatch into metatrochophore larvae. After six days, these grow their first segment with parapodia and develop into chaetigerous larvae. Three weeks later they start to grow the pharyngeal apparatus they need as an adult and when this is complete they are juvenile worms. They continue to grow, adding a new segment every two days. They are mature at a length of about forty segments.

References

{{Taxonbar, from=Q2221561 Syllidae Animals described in 1852 Taxa named by August David Krohn