Sclerasterias is a genus

Genus

In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...

 of starfish in the family

Family (biology)

In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...

 Asteriidae

Asteriidae

Asteriidae is a family of Asteroidea in the order Forcipulatida.-Genera:Genera within the family Asteriidae include:* Ampheraster Fisher, 1923 * Anteliaster Fisher, 1923 * Aphanasterias * Asterias Linnaeus, 1758...

. Adult individuals have five arms but small, immature individuals have six. This led to the giving of a separate generic name to the juveniles, Hydrasterias, before it was realised that only one genus was involved. These young individuals often undergo fissiparity

Asexual reproduction

Asexual reproduction is a mode of reproduction by which offspring arise from a single parent, and inherit the genes of that parent only, it is reproduction which does not involve meiosis, ploidy reduction, or fertilization. A more stringent definition is agamogenesis which is reproduction without...

. The disc splits into two parts, each bearing three arms, and new arms develop on each part to complete the complement of arms. This sometimes happens repeatedly and may be an adaptation to life in cold, deep seas where most of the species are found.

Species

The following species

Species

In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...

 are accepted by the World Register of Marine Species:

• Sclerasterias alexandri (Ludwig, 1905)
• Sclerasterias contorta (Perrier, 1881)
• Sclerasterias euplecta (Fisher, 1906)
• Sclerasterias eustyla (Sladen, 1889)
• Sclerasterias guernei Perrier, 1891
• Sclerasterias heteropaes Fisher, 1924
• Sclerasterias mazophora (Wood-Mason & Alcock, 1891)
• Sclerasterias mollis (Hutton, 1872)
• Sclerasterias neglecta (Perrier, 1891)
• Sclerasterias parvulus (Perrier, 1891)
• Sclerasterias richardi (Perrier, 1882)
• Sclerasterias satsumana Doderlein, 1902
• Sclerasterias tanneri (Verrill, 1880)