Heliaster solaris commonly known as 24-rayed sunstar is a possibly extinct sea star which was known from the waters near Española Island in the Galápagos Islands. The species was endemic to the Galápagos Island group, where it appears to have been strictly restricted to the waters around the Isla Espanola.
| Heliaster solaris | |
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Scientific classification 
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| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Echinodermata |
| Class: | Asteroidea |
| Order: | Forcipulatida |
| Family: | Heliasteridae |
| Genus: | Heliaster |
| Species: | H. solaris
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| Binomial name | |
| Heliaster solaris A. H. Clark, 1920
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Description
editHeliaster solaris had 22 to 24 cylindrical and elongated more or less distinctly banded rays which were tapering at the ends. They were one third longer than the diameter of the body. The dorsal rows of the spines were longer and more compressed. The spines, pedicellariae, and the madreporic plate were light yellowish. It hasn’t been seen in the wild since 1983. The Heliaster Solaris is poorly-understood and rarely documented species of sea star. The 24-rayed sunstar may be synonymous with another species in the Heliaster species complex that lives in the east Pacific. The 24-rayed sunstar, also known as Heliaster solaris, can grow up to 3 inches long
Taxonomy
editThis species was first mentioned by John Edward Gray in 1840 in the Annals and Magazine of Natural History as Asterias multiradiata and later as Heliaster multiradiatus. Due to the fact that Carl Linnaeus used the name Asterias multiradiata (current accepted name: Capillaster multiradiata) already in 1758 Gray's name became an invalid homonym. In 1920 Austin Hobart Clark published the replacement name Heliaster solaris.It was first found on San Cristóbal Island in the early 1830s.
Hunting
editHeliaster solaris hunts by catching food as it floats or chasing it down. The 24-rayed sunstar's or Heliaster solaris tube feet, spines, and pedicellariae are sensitive to touch and chemicals. The tube feet at the tips of the rays are particularly sensitive to chemicals, allowing the Heliaster solaris to detect odors, such as food. The Heliaster solaris also has eyespots at the ends of its arms, each containing 80–200 ocelli. Like other Sea stars. Heliaster solaris eats Sponges, Sea anemones, Mollusks, Polychaetes, Crustaceans, Other echinoderms
Protection
editHeliaster solaris have predators like any other star fish if a Heliaster solaris is threaten. Heliaster solaris have sharp and well-developed spines, which are thought to be used primarily for defense. Spines can hurt reckless mouths. Heliaster solaris Also have chemical-based defenses, such as slime, or toxic chemicals in their body wall.
Lifecycle and Reproduction
editMembers of the class Asteroidea (including Heliaster solaris) exhibit both asexual (regeneration and clonal) and sexual (gonochoric) means of reproduction. Life cycle: Embryos hatch into planktonic larvae and later metamorphose into pentamorous juveniles which develop into young sea stars with stubby arms. Adults usually have between 10 and 24 arms, while juveniles have only 5.
Extinction
editIn the early 1980s the Galápagos Islands were affected by the El Niño-Southern Oscillation event. The increase of the water temperatures led to the turning off of the plankton production and species like the 24-ray-rayed Sunstar or Heliaster solaris could not find again. despite a 25 years survey. The Heliaster solaris was declared extinct in 2009. And they decided that they possibly went extinct in 1983 because of the Event years ago. And combined with the effects of an increasingly heavy tourism industry in the islands at the Time, appears to have led to the specie’s decline and possible extinction.
References
edit- John Edward Gray: Mr. J. E. Gray's Synopsis of the Genera and Species of Starfish In: Annals and Magazine of Natural History Volume 6, 1840. p. 180
- Austin Hobart Clark: A New Name for Heliaster multiradiatus (Gray). In: Proceedings of the Biological Society of Washington, 1920. p. 183
- Graham J. Edgar et al.: El Niño, grazers and fisheries interact to greatly elevate extinction risk for Galapagos marine species In: Global Change Biology 23 October 2009 doi:10.1111/j.1365-2486.2009.02117.x