Sand corals
| Sand corals | ||||||||||||
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| Systematics | ||||||||||||
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| Scientific name | ||||||||||||
| Sabellariidae | ||||||||||||
| Johnston , 1865 |
The sandy coral ( Sabellariidae ) are a family of sessile, röhrenbauender , in many cases reef-building , as filter feeders living polychaete (Polychaeta), which are found in oceans worldwide.
features
The Sabellariidae have short, compact bodies that are a few millimeters to 6 cm long, depending on the species, and are clearly divided into four sections by their conspicuous segmentation . The foremost section consists of two short segments with unbranched parapodia , on which only capillary-like bristles sit ventrally. The parathorax is composed of three to four segments, on which forked parapodia with dorsal cirrus-shaped gills, strong rudder-shaped bristles on the notopodia and capillary-shaped bristles on the neuropodia sit. The abdomen is formed by numerous segments on which forked parapodia with dorsal cirrus-shaped gills branchiae, hooks on the notopodia and capillary-shaped bristles sit on the neuropodia. The tail section, on the other hand, comprises rudimentary bristle-less segments that are bent back under the body. The bristles have a so-called bristle inversion: the hooks are located on the notopodia and not the neuropodia, and the bristles include capillary bristles, spikes and hooks with various decorations.
The head end consists of a operculum, with which the cylindrical housing tube is closed, numerous gold-colored wide specialized bristles ( Paleae ) around the mouth and buccal - cirri which almost completely fill the entrance of the molded sand and mucus burrow. The prostomium is fused dorsally with the peristomium and is therefore difficult to see, but it forms at least a central keel, while the peristomium can only be seen as lips around the mouth. The animals have no antennas. On the side of the midrib of the prostomium sits a pair of palps , next to the base of which inward are the nuchal organs .
The first segment, which is completely fused with the head, and the following segment, together with the bristles of the notopodia, form the operculum, which, depending on the species, consists of two more or less fused lobes or stems. The neuropodia have the shape of short cylinders, while the notopodia are reduced to tori . There are neither dorsal nor ventral cirruses, and there are also no epidermal papillae, cirrus pygidium, aciculae, a buccal organ, and a throat membrane. The flattened gills sit on the back.
The longitudinal muscles are arranged in bundles. The intestinal canal is a straight tube. The mixonephridia consist of a single anterior pair of kidneys and posterior gonoducts. The closed blood vessel system has a heart .
Distribution, way of life and example species
The Sabellariidae are widespread in seas around the world and live predominantly on sandy or muddy surfaces.
All Sabellariidae build cylindrical living tubes from slime and grains of sand that are firmly cemented to hard, rocky substrate, and most live in colonies that can often form large reefs - including the Sabellaria alveolata , which used to be common in the North Sea . The majority of the species occur in shallow water including the intertidal zone, but there are two genera with representatives on the continental slopes. Sabellaria cementarium forms reefs in some areas but does not live in colonies in others.
The Sabellariidae feed as filter feeders of detritus .
Development cycle
The Sabellariidae are separate sexes with an approximately equal number of females and males. They live to be around 3 to 10 years old. The eggs are not formed at the same time, as different stages of development are found in a female. The yolk is formed before the eggs get into the coelom fluid . Fertilization takes place after the eggs have been released into the open sea, and young trochophora larvae swim around 12 hours later . The development as a free-swimming larva takes about 2 months, depending on the species, until the mature larva, which at the end is already recognizable as Sabellariid with its paleae, sinks to the ground and metamorphoses into a crawling worm .
Up to 4 million individuals per square meter can live in newly populated areas, but this reduces to around 12,000 to 15,000 individuals per square meter in a few months.
Genera
The Sabellariidae family is divided into 12 genera :
- Bathysabellaria Lechapt & Gruet, 1993
- Gesaia Kirtley, 1994
- Gunnarea Johannson, 1927
- Idanthyrsus Kinberg, 1876
- Lygdamis Kinberg, 1867
- Mariansabellaria Kirtley, 1994
- Neosabellaria Kirtley, 1994
- Paraidanthyrsus Kirtley, 1994
- Phalacrostemma Marenzeller, 1895
- Phragmatopoma Mörch, 1863
- Sabellaria Lamarck, 1818
- Tetreres Caullery, 1913
literature
- Stanley J. Edmonds: Fauna of Australia, Volume 4A. Polychaetes & Allies. The Southern Synthesis 4. Commonwealth of Australia, 2000. Class Polychaeta. Pp. 239-243, Family Sabellariidae.
Web links
Individual evidence
- ↑ Sabellariidae Johnston, 1865. WoRMS , 2018. Retrieved October 29, 2018.