Sternaspidae

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Sternaspidae
Sternaspis thalassemoides. Iconographia Zoologica, Amsterdam

Sternaspis thalassemoides . Iconographia Zoologica , Amsterdam

Systematics
Trunk : Annelids (Annelida)
Class : Polychaete (Polychaeta)
Subclass : Palpata
Order : Canalipalpata
Subordination : Terebellida
Family : Sternaspidae
Scientific name
Sternaspidae
Carus , 1863
Sternaspis affinis with retracted front end (rear end with gills on the right)

Sternaspidae is the name of a family of small, squat, polychaeta (polychaeta) living in mud , which can be found in oceans worldwide as detritus eater .

features

The Sternaspidae are characterized by a short, stocky body with only a few segments and a flat belly side, which usually narrows slightly in the middle and can reach up to 31 mm in length with 22 segments. There are bundles of bristles at both the front and rear ends . The rearmost segments are fused on the abdomen to form a two-part, reddish end shield stiffened by chitin and surrounded by the rear bristles. The body is whitish due to the lack of pigments, the long, thread-like gills , which are located in two bundles on the back at the end of the body, are colored red.

The prostomium of the Sternaspidae is clearly separated and cut off in front, while the peristomium is reduced to lips around the mouth. Antennae and palps are absent, as are nuchal organs, while eye-spots are only found in some species. The longitudinal muscles are arranged in many strands and the segmentation is clear. The first segment is similar to the following and has similar bristles. The entire front body section is retractable. The parapodia are two-branched on all segments in front of the end shield, while they only have notopodia at the end shield, which consist of very short, cut cylinders. In general, the branches of the parapodia are short, barely raised papillae, and there are no dorsal, ventral or anal cirruses. The epidermal papillae resemble those of the Flabelligeridae . The animals have no aciculae. The bristles are capillary-shaped or heavy spikes.

The sac-shaped pharynx can be everted and the intestinal canal is folded. The animals do not have a throat membrane. The closed blood vessel system has no central heart. The nephridia are designed as mixonephridia, with the first pair serving as kidneys, the gametes being released through the rest .

distribution and habitat

The star aspidae are distributed in seas around the world from shallow waters to the deep sea . Sternaspis scutata is found cosmopolitan from the Arctic to the Antarctic from the shores to great depths. The animals live in sandy and muddy sediment soils, preferring sea depths of 100 to 200 m and rarely appearing in large numbers.

Reproductive cycle

The Sternaspidae are separate sexes and have paired gonads behind their sixth segment . As far as is known, their free-swimming larvae are fed on yolk reserves and sink less than two days after fertilization to metamorphose into crawling worms . This way of life, with larvae swimming for only a short time, is an obstacle to the cosmopolitan distribution of the species.

Diet and Lifestyle

The star aspidae feed on detritus , which they swallow as substrate eater mainly with sediment particles with the help of their evertable pharynx and then digest it, while the mineral components are excreted unchanged.

The animals lie upside down in the mud so that the gills are on the surface of the sediment and are thus supplied with oxygen.

Genera and species

The Sternaspidae were long counted as a monogeneric family with the only genus Sternaspis Otto, 1820 , but in 2013 Sendall & Salazar-Vallejo described two new genera with several species: Caulleryaspis and Petersenaspis .

The 37 species of the Sternaspidae family are divided into 3 genera :

literature

  • Julius Victor Carus: Vermes , in WCH Peters, JV Carus, CEA Gerstäcker (Hrsg.): Handbuch der Zoologie . Wilhelm Engelmann, Leipzig 1863, pp. 422 - 484, here p. 453, Sternaspidea .
  • Adolfus Guilielmus Otto: De Sternaspide thalassemoideo et Siphostomate diplochaito vermibus duobus marinis. [Epistola Gratulatoria quam ad celebrandum diem laetissimum VI Marti MDCCCXX (etc, etc)]. Vratislaviae 1820. p. 16, 2 plates.
  • Kelly Sendall, Sergio Salazar-Vallejo, 2013. Revision of Sternaspis Otto, 1821 (Polychaeta, Sternaspidae). ZooKeys 286 (0), pp. 1-74 PMC 3677357 (free full text).
  • Stanley J. Edmonds: Fauna of Australia, Volume 4A. Polychaetes & Allies. The Southern Synthesis 4. Commonwealth of Australia, 2000. Class Polychaeta. Pp. 301-303, Family Sternaspidae.
  • Kristian Fauchald, Peter A. Jumars (1979): The diet of worms: A study of polychaete feeding guilds. Oceanography and Marine Biology Annual Review 17, pp. 193-284.

Web links

Commons : Sternaspidae  - Collection of images, videos, and audio files

Individual evidence

  1. ↑ Sternaspidae Carus, 1863. WoRMS , 2018. Accessed December 9, 2018.