''Scolelepis squamata'' is a

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...

polychaete worm Polychaeta () is a paraphyletic class of generally marine annelid worms, commonly called bristle worms or polychaetes (). Each body segment has a pair of fleshy protrusions called parapodia that bear many bristles, called chaetae, which are made ...

in the

family Family (from la, familia) is a group of people related either by consanguinity (by recognized birth) or affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its members and of society. Idea ...

Spionidae Spionidae is a family of marine worms within the Polychaeta. Spionids are selective deposit feeders that use their two grooved palps Pedipalps (commonly shortened to palps or palpi) are the second pair of appendages of chelicerates – a grou ...

. It occurs on the lower shore of coasts on either side of the Atlantic Ocean.

Description

''Scolelepis squamata'' is a slender, bluish-green worm with a maximum length of about and over two hundred segments when fully grown. The prostomium (head) is diamond-shaped and has four eyes, arranged in a trapezoid fashion, two long slender palps, and no central antenna. Each segment has a pair of

parapodia In invertebrates, the term parapodium ( Gr. ''para'', beyond or beside + ''podia'', feet; plural: parapodia) refers to lateral outgrowths or protrusions from the body. Parapodia are predominantly found in annelids, where they are paired, unjointed ...

with

chaeta A chaeta or cheta (from Greek χαίτη “crest, mane, flowing hair"; plural: chaetae) is a chitinous bristle or seta found in annelid worms, (although the term is also frequently used to describe similar structures in other invertebrates such ...

(bristles). The dorsal lobes of the parapodia are long and thin and are fused to the

gills A gill () is a respiratory organ that many aquatic organisms use to extract dissolved oxygen from water and to excrete carbon dioxide. The gills of some species, such as hermit crabs, have adapted to allow respiration on land provided they are ...

for half their length. The ventral lobes are rounded and short, and slightly bilobed from segment 20 onwards. There are gills (red) on all segments except segment 2 and the last seven body segments.

Distribution and habitat

''Scolelepis squamata'' is found on both sides of the Atlantic Ocean, the Mediterranean Sea, the Caribbean Sea and the Gulf of Mexico. It digs a burrow in the sediment in the lower parts of the shore and the shallow sublittoral. Typically it chooses sandy beaches in the intertidal zone and sandy and silty sediments in subtidal flats. It tolerates low salinity levels and is often found in estuaries.

Biology

A monograph of the British marine annelids 1915 XC

''Scolelepis squamata'' lives in a mucous reinforced, vertical burrow in the sediment. It uses the long palps to feed on organic particles on the nearby seabed. The palps do not have a ciliated groove, so the particles are brought to the pharynx by a contraction of the whole palp. If there is a current, each palp can be coiled up in a helix, and the animal can feed entirely on suspended particles. Examination of the contents of the gut showed sediment particles, faecal pellets of other animals and a variety of embryos, larvae and juvenile prey. On the south coast of Britain, this worm breeds between March and July; sperm and eggs are released into the sea where fertilisation takes place, and the larvae are

plankton Plankton are the diverse collection of organisms found in water (or air) that are unable to propel themselves against a current (or wind). The individual organisms constituting plankton are called plankters. In the ocean, they provide a crucia ...

ic for about five weeks before settling on the seabed and developing into juvenile worms. In Brazil, it is one of the commonest species of worm on some intertidal beaches. Here it breeds all year round, with peak recruitment of juveniles in April and October. This worm has a short life-span and seems to have adopted a strategy of high growth rate, high reproductive effort and opportunistic behaviour.

References

{{Taxonbar, from=Q2327196 Canalipalpata Animals described in 1806