''Sphaerosyllis georgeharrisoni'' is a species belonging to the phylum
Annelida
The annelids (), also known as the segmented worms, are animals that comprise the phylum Annelida (; ). The phylum contains over 22,000 extant species, including ragworms, earthworms, and leeches. The species exist in and have adapted to variou ...
, a group known as the segmented worms.
''Sphaerosyllis georgeharrisoni'' is distinct by its large parapodial glands with hyaline material; by its small size; short
proventricle; a median antenna that is inserted posteriorly to the lateral antennae; as well as long
pygidial papillae. Juveniles of
''
S. hirsuta'' are very similar to this species. ''Sphaerosyllis pygipapillata'' has all of its antennae aligned, a smooth dorsum, while its pygidial papillae are longer and slender.
The species' name honours
George Harrison
George Harrison (25 February 1943 – 29 November 2001) was an English musician, singer and songwriter who achieved international fame as the lead guitarist of the Beatles. Sometimes called "the quiet Beatle", Harrison embraced Culture ...
, musician who died prior to the species' describing article's publication.
Description
The species' body is small, with a total length of and width of , including 26 chaetigers. It possesses small papillae that cover its dorsum, extending to its palps and parapodia, being quite numerous on its midbody. Its
prostomium
The prostomium (From Ancient Greek, meaning "before the mouth"; : prostomia; sometimes also called the "acron") is the Cephalization, cephalized first body segment in an annelid worm's body at the anterior end. It is in front of (but does not in ...
is rectangular and is mostly covered by the
peristomium
The peristomium is the first true body segment in an annelid worm's body in the anterior end. It is directly behind the prostomium and contains the mouth, tentacular cirri, and sometimes feeding palps, which may instead occur on the prostomium. If ...
, showing 4 eyes in a trapezoidal arrangement. Its
antennae are similar in length to the prostomium; they have bulbous bases and moderate tips.
Its
tentacular
In zoology, a tentacle is a flexible, mobile, and elongated organ present in some species of animals, most of them invertebrates. In animal anatomy, tentacles usually occur in one or more pairs. Anatomically, the tentacles of animals work mainl ...
cirri are similar but shorter than the antennae; the dorsal cirri are short, similar in length to its tentacular cirri. Its parapodial glands are large, with
hyaline
A hyaline substance is one with a glassy appearance. The word is derived from , and .
Histopathology
Hyaline cartilage is named after its glassy appearance on fresh gross pathology. On light microscopy of H&E stained slides, the extracellula ...
material present. Its anterior parapodia have about 5 compound chaetae each, with
unidentate
In coordination chemistry, denticity () refers to the number of donor groups in a given ligand that bind to the central metal atom in a coordination complex. In many cases, only one atom in the ligand binds to the metal, so the denticity equals ...
blades provided with long spines which are longer on dorsal chaetae, exhibiting dorsoventral gradation in length. Posterior parapodia, on the other hand, possess 3 compound chaetae with larger shafts and shorter blades which are slightly hooked.
The dorsal simple
chaeta
A chaeta or cheta (; ) is a chitinous bristle or seta found on annelid worms, although the term is also frequently used to describe similar structures in other invertebrates such as arthropods. Polychaete annelids (''polychaeta'' literally me ...
e from chaetiger 1 are unidentate and show long marginal spines. Its ventral simple chaetae on the posterior
parapodia
In invertebrates, the term parapodium ( Gr. ''para'', beyond or beside + ''podia'', feet; : parapodia) refers to lateral outgrowths or protrusions from the body. Parapodia are predominantly found in annelids, where they are paired, unjointed late ...
are sigmoid, smooth and unidentate. Its
acicula
Acicula (: aciculum) are strong, stout internal chaeta
A chaeta or cheta (; ) is a chitinous bristle or seta found on annelid worms, although the term is also frequently used to describe similar structures in other invertebrates such as art ...
is solitary, with tips bent to a right angle.
The pharynx spans approximately 3 segments and is relatively slender, its
pharyngeal tooth located anteriorly. Its
proventricle spans through 1 segments, with 13-14
muscle cell
A muscle cell, also known as a myocyte, is a mature contractile Cell (biology), cell in the muscle of an animal. In humans and other vertebrates there are three types: skeletal muscle, skeletal, smooth muscle, smooth, and Cardiac muscle, cardiac ...
rows. Its
pygidium
The pygidium (: pygidia) is the posterior body part or shield of crustaceans and some other arthropods, such as insects and the extinct trilobites. In groups other than insects, it contains the anus and, in females, the ovipositor. It is compos ...
is small, with a few long
papillae and 2 anal cirri, which are similar in shape to the dorsal cirri but longer.
Distribution
''S. georgeharrisoni'' was found in areas near or at the
Houtman Abrolhos
The Houtman Abrolhos (often called the Abrolhos Islands) is a chain of 122 islands and associated coral reefs in the Indian Ocean off the west coast of Australia about west of Geraldton, Western Australia. It is the southernmost true coral r ...
up until
Carnarvon, Western Australia
Carnarvon ( ) is a coastal town situated approximately north of Perth, in Western Australia. It lies at the mouth of the Gascoyne River on the Indian Ocean. The Shark Bay World Heritage Site, world heritage area lies to the south of the town an ...
, at a depth of between in dead
coral
Corals are colonial marine invertebrates within the subphylum Anthozoa of the phylum Cnidaria. They typically form compact Colony (biology), colonies of many identical individual polyp (zoology), polyps. Coral species include the important Coral ...
s and sand on
coral reef
A coral reef is an underwater ecosystem characterized by reef-building corals. Reefs are formed of colonies of coral polyps held together by calcium carbonate. Most coral reefs are built from stony corals, whose polyps cluster in group ...
s in shallow waters. Its distribution is thought to include the whole of WA.
References
Further reading
*
*
*
External links
WORMS entry
{{Taxonbar, from=Q2709039
Syllidae
Animals described in 2005