Asterina phylactica
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| Emson & Crump , 1979 |
Asterina phylactica is a very small starfish from the Asterinidae familyin the order of the valve stars (Valvatida) thatis native tothe eastern North Atlantic and feeds mainly on bacteria and diatoms . He hatches his young.
features
Asterina phylactica has a flattened, pentagonal shape with 5 short blunt arms and a maximum diameter of 1.5 cm, making it one of the smallest starfish in the world. Its upper side is olive green with a star-shaped brown markings in the center and delimited from the whitish lower side by a clear edge. It also differs from the closely related Asterina gibbosa in that it has fewer plates around the mouth opening.
Reproductive cycle
In contrast to most other starfish - also in the Asterinidae family - Asterina phylactica is a hermaphrodite . In the first year of life, Asterina phylactica only produces sperm, but in the following year it becomes a simultaneous hermaphrodite and produces both sperm and egg cells. In late spring, many individuals come together and expel sperm into the water so that the eggs are fertilized. These remain on the underside of the mother sea star and are incubated here for about three weeks. In contrast to almost all other starfish, the embryos develop directly without a free-swimming larval stage and metamorphose under the protective maternal umbrella into juvenile starfish, which ultimately leave the mother's care. The starfish live to be around 2 years old and die after they have released their brood.
Distribution and occurrence
Asterina phylactica is found in the eastern North Atlantic along the west coast of England , Wales , Scotland and north-western Ireland , as well as in the Mediterranean and the Adriatic . Here it typically lives in tidal pools with lots of calcareous red algae (Corallinales). The species tolerates stronger salt and temperature fluctuations.
nutrition
Asterina phylactica feeds on bacteria and diatoms that live on the surface of rocks. To do this, she turns her stomach out, presses it against the rock and excretes digestive enzymes so that the microorganisms are digested extraintestinally .
Taxonomy
In the past, these starfish were included in the species Asterina gibbosa , but due to the significantly different reproductive strategies, Asterina phylactica was described as a separate species in 1979.
literature
- Robin G. Crump, Roland H. Emson (1983): The natural history, life history and ecology of the two British species of Asterina . Field Studies 5 (5), pp. 867-882.
- Roland H. Emson, Robin G. Crump (1979): Description of a new species of Asterina (Asteroidea), with an account of its ecology . Journal of the Marine Biological Association of the United Kingdom 59. pp. 77-94.
- Roland H. Emson, Robin G. Crump (1978): Brooding in Asterina gibbosa Pennant . Thalassia Jugoslavia 12 (1), pp. 99-108.
Web links
- Morvan Barnes: Asterina phylactica - A cushion star . Marine Life Information Network, Biology and Sensitivity Key Information Sub-programs. Marine Biological Association of the United Kingdom, Plymouth 2009.
- Robin G. Crump: Cushion stars . Field Studies Council, 2008.
Individual evidence
- ^ A b Morvan Barnes: Asterina phylactica . Marine Life Information Network. 200. Retrieved November 13, 2015.
- ^ Robin G. Crump: Cushion stars . In: The Seashore . Field Studies Council. 2008. Retrieved October 31, 2013.
- ↑ WoRMS
- ↑ a b Robin G. Crump, Roland H. Emson: The natural history, life history and ecology of the two British species of Asterina . In: Field Studies . 5, No. 5, 1983, pp. 867-882.
- ^ Roland H. Emson, Robin G. Crump: Description of a new species of Asterina (Asteroidea), with an account of its ecology . In: Journal of the Marine Biological Association of the United Kingdom . 59, 1979, pp. 77-94.