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 an eversible pharynx is present, it is contained in this segment as well, and can fill up to 20 segments when inverted, depending on the species.
The annelids, also known as the ringed worms or segmented worms, are a large phylum, with over 22,000 extant species including ragworms, earthworms, and leeches. The species exist in and have adapted to various ecologies – some in marine environments as distinct as tidal zones and hydrothermal vents, others in fresh water, and yet others in moist terrestrial environments.
The prostomium is the first body segment in an annelid worm's body in the anterior end. It is in front of the mouth, being usually a small shelf- or lip-like extension over the dorsal side of the mouth.
The prostomium and peristomium can be variously fused, either completely distinct, or comprising a joint structure of a peristomial ring and a tentacular crown. [1]
Nereididae are a family of polychaete worms. It contains about 500 – mostly marine – species grouped into 42 genera. They may be commonly called ragworms or clam worms.
Eunicida is an order of polychaete worms.
Phyllodocida is an order of polychaete worms in the subclass Aciculata. These worms are mostly marine though some are found in brackish water. Most are active benthic creatures, moving over the surface or burrowing in sediments, or living in cracks and crevices in bedrock. A few construct tubes in which they live and some are pelagic, swimming through the water column. There are estimated to be about 3,500 species in the order.
Psammodrilus balanoglossoides is a species of meiofaunal polychaete annelid only found in France and the North Sea, it is one of the five species representing the genus Psammorilus.
Scalibregma inflatum, also known as T headed worm, is a burrowing marine polychaete. It is a cosmopolitan species that can be found from the Arctic to Antarctica, although most probably several species are confounded.
Prosphaerosyllis battiri is a species belonging to the phylum Annelida, a group known as the segmented worms. The species name comes from an Aboriginal word, battiri, meaning "rough". Prosphaerosyllis battiri is a species characterized by having only partially fused palps, an unretracted prostomium on its peristomium or showing only slight retraction, the shape of its dorsal cirri and its arrangement of papillae, being numerous anteriorly while less numerous posteriorly. It resembles Prosphaerosyllis semiverrucosa, but its arrangement of dorsal papillae is reversed.
Salvatoria pilkena is a species belonging to the phylum Annelida, a group known as the segmented worms. The species name comes from an Aboriginal word, pilkena, meaning "different", due to its characteristic features. Salvatoria pilkena belongs to a reduced group of species that possess rugose dorsal cirri, contrary to the typical spindle-shaped cirri found in its genus. It also lacks dorsal cirri on chaetiger 2. It resembles Salvatoria swedmarki and S. celiae, differing from pilkena in that the latter has significantly longer proventricles, while its compound chaetae are short and unidentate. At the same time, S. opisthodentata has a similar body and compound chaetae but appears to possess dorsal cirri on its chaetiger 2.
Salvatoria koorineclavata is a species belonging to the phylum Annelida, a group known as the segmented worms. This species has been described in Australia as Brania clavata before. Both of those species are similar, the Australian species, however, has a longer pharynx and proventricle; at the same time, blades of chaetae are present in the Australian species, with longer and upwards curved spines, which are straight in S. clavata; its pharyngeal tooth is located more anteriorly than in S. clavata. Other global species, like those in Brania genus, are also similar to S. koorineclavata. Salvatoria californiensis has similar chaetae, with shorter spines and less developed teeth. Its acicula lacks a defined acute tip, and the proventricle is quite shorter, running through 5 segments in S. koorineclavata, with fewer rows of muscle cells. The species name comes from an Aboriginal word, Koorine, meaning "daughter", due to the similarity of the Australian species to the European species of S. clavata.
Erinaceusyllis ettiennei is a species belonging to the phylum Annelida, a group known as the segmented worms. E. ettiennei is characterized by its compound chaetae with slender and thin blades, which are curved as a sabre. The most similar species is Erinaceusyllis serratosetosa, but is differentiated by the size of its body and the compound chaetae, which have long and curved marginal spines on its long blades in E. serratosetosa. The species is named in honour of Ettienne Fourie.
Erinaceusyllis cirripapillata is a species belonging to the phylum Annelida, a group known as the segmented worms. E. cirripapillata is characterized by its papillae on its dorsal cirri, one of them being distinctively mushroom-shaped. No species of this genus or Sphaerosyllisis is known to possess this particular kind of papillae. The name of the species refers to these same papillae.
Erinaceusyllis hartmannschroederae is a species belonging to the phylum Annelida, a group known as the segmented worms. This species was previously described in Australia as Sphaerosyllis erinaceus and S. erinaceus erinaceus, a species distributed throughout the globe. These species appear to be a species complex. Previous descriptions stated that the two aforementioned species possess compound chaetae blades which are long and slender. Several subspecies of S. erinaceus were described on the basis of differences in shapes and sizes of their compound chaetae; such differences are enough to consider them as distinct species. The species is named in honour of Gesa Hartmann-Schröder, an expert on syllid species.
Erinaceusyllis kathrynae is a species belonging to the phylum Annelida, a group known as the segmented worms. E. kathrynaen is similar to E. cirripapillata, but lacks characteristic papillae on its cirri. At the same time, Sphaerosyllis perspicax - which according to San Martín (2005) could belong to the Erinaceusyllis genus - is also similar, but its anterior dorsal cirri are inflated at their bases; the eyes and antennae are arranged linearly, and the palps are fused along their length. This species is named in honour of Kathryn Attwood of the Australian Museum.
Sphaerosyllis voluntariorum is a species belonging to the phylum Annelida, a group known as the segmented worms. This species is closely related to Sphaerosyllis bifurcata, Sphaerosyllis bifurcatoides and Sphaerosyllis rotundipapillata, all endemic species to Australia, characterized by having large dorsal papillae, sometimes trilobed, and with shafts of compound chaetae distally bifid. S. voluntariorum is more densely papillated on its anterior segments and has a long subdistal spine on the ventral simple chaetae. This species' name alludes to the volunteers of the Marine Invertebrate section of The Australian Museum, who sorted specimens of syllids that led to the description of this animal.
Sphaerosyllis goorabantennata is a species belonging to the phylum Annelida, a group known as the segmented worms. Sphaerosyllis goorabantennata is distinct by its small size, small and unevenly distributed papillae, as well as by its particularly long antennae and tentacular cirri. Sphaerosyllis minima and S. minima magnapapillata are also small, but their antennae and tentacular cirri are significantly shorter, like its cogenerate species. The species' name is derived from the Aboriginal word gooraba, meaning "big", alluding to its long antennae.
Sphaerosyllis georgeharrisoni is a species belonging to the phylum Annelida, 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, musician who died prior to the species' describing article's publication.
Phyllodoce maculata is a species of Polychaete worm in the family Phyllodocidae. It is native to the northeastern Atlantic Ocean where it inhabits shallow water areas of sand, mud and stones.
Phyllochaetopterus prolifica is a species of marine polychaete worms that live in a tube that it constructs. It is native to shallow waters in the eastern Pacific Ocean and forms colonies of tubes on rocks and submerged objects.
Acromegalomma interruptum is a bristle worm from the Sabellidae family. The body of the worm consists of a head, a cylindrical, segmented body and a tailpiece. The head consists of a prostomium and a peristomium and carries paired appendages.
Sternaspidae, commonly known as mud owls, are a family of marine polychaete worms with short swollen bodies. They have a global distribution and live buried in soft sediment at depths varying from the intertidal zone to 4,400 m (14,400 ft).