''Syllis ramosa'' is a
species
In biology, a species is the basic unit of Taxonomy (biology), 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 ...
of
polychaete worm 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 ...
Syllidae.
It is found in the deep sea where it lives within the tissues of a sponge. It was the first branching polychaete worm to be discovered, with each worm having a single head and multiple anuses.
History
During the period 1872 to 1876, the
Royal Navy
The Royal Navy (RN) is the United Kingdom's naval warfare force. Although warships were used by Kingdom of England, English and Kingdom of Scotland, Scottish kings from the early medieval period, the first major maritime engagements were foug ...
's
HMS ''Challenger'' was used in the
''Challenger'' expedition to survey and explore the world's oceans. One of the unknown animals dredged from the ocean depths near the Philippines was a species of
sponge which was found to contain numerous branching worms inside its cavities. In 1879, one of these worms was
formally described by the Scottish marine biologist
William Carmichael McIntosh
William Carmichael M'Intosh LLD (also spelt McIntosh; 10 October 1838, St Andrews – 1 April 1931, St Andrews) was a Scottish physician and marine zoologist. He served as president of the Ray Society, as vice-president of the Royal Societ ...
, who named it ''Syllis ramosa''.
[ Branching polychaete worms were previously unknown.]
Distribution
This bristle worm was first discovered living commensally with a sponge at a depth of about near the Philippines and at a depth of in the Arafura Sea.[ Further branching worms have occasionally been found in different locations and have been ascribed to ''S. ramosa'' despite subtle differences in morphology; they are hard to examine because of the difficulty of extracting them from the sponge tissue. However a new species of branching worm ('' Ramisyllis multicaudata'') was described in 2012.][
]
Ecology
The heads of the two individual ''S. ramosa'' brought to the surface by the ''Challenger'' were located in the bases of glass sponges of the class Hexactinellida. The rest of the worms' bodies were in the passages of the sponges. The bodies branched repeatedly so that each worm had a single head and many anuses.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 ...
", and develops an extra head with large eyes and no mouth. The gut in this part of the animal is absorbed, the muscles are rearranged to facilitate swimming and the stolon becomes a storage receptacle for the eggs or sperm. When the breeding period arrives, the stolon becomes detached and swims to the surface of the sea, in a process termed "epitoky
Epitoky is a process that occurs in many species of polychaete marine worms wherein a sexually immature worm (the atoke) is modified or transformed into a sexually mature worm (the epitoke). Epitokes are pelagic morphs capable of sexual repro ...
". Here the gametes are released and the stolon dies. Meanwhile, the parent worm remains safely in its sponge home and produces more stolons.
References
{{Taxonbar, from=Q1932407
Syllidae
Animals described in 1879