''Meyenaster'' is a

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

starfish Starfish or sea stars are Star polygon, star-shaped echinoderms belonging to the class (biology), class Asteroidea (). Common usage frequently finds these names being also applied to brittle star, ophiuroids, which are correctly referred to ...

in the

family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...

Asteriidae The Asteriidae are a diverse family of Asteroidea (sea stars) in the order Forcipulatida. It is one of three families in the order Forcipulatida. The oldest unambiguous fossils of the family date to the Late Cretaceous. Genera The World Regi ...

. It is a

monotypic In biology, a monotypic taxon is a taxonomic group (taxon) that contains only one immediately subordinate taxon. A monotypic species is one that does not include subspecies or smaller, infraspecific taxa. In the case of genera, the term "unisp ...

genus and the only species is ''Meyenaster gelatinosus'' which was first described by the Prussian botanist and zoologist

Franz Julius Ferdinand Meyen Franz Julius Ferdinand Meyen (28 June 1804 – 2 September 1840) was a Prussian physician and botanist. Meyen was born in Tilsit, East Prussia. In 1830 he wrote ''Phytotomie'', the first major study of plant anatomy. Between 1830 and 1832, he to ...

in 1834. It is found in the southeastern Pacific Ocean on the coasts of South America.

Description

''Meyenaster gelatinosus'' is a white starfish with six arms and a mean radius ranging from .

Distribution and habitat

''Meyenaster gelatinosus'' is native to the southeastern Pacific Ocean where it is found on the coasts of Chile. It is abundant in

kelp Kelps are large brown algae or seaweeds that make up the order (biology), order Laminariales. There are about 30 different genus, genera. Despite its appearance and use of photosynthesis in chloroplasts, kelp is technically not a plant but a str ...

forests in the

subtidal zone The neritic zone (or sublittoral zone) is the relatively shallow part of the ocean above the drop-off of the continental shelf, approximately in depth. From the point of view of marine biology it forms a relatively stable and well-illuminated ...

as well as being found on sand and gravel bottoms, and among

seagrass Seagrasses are the only flowering plants which grow in marine (ocean), marine environments. There are about 60 species of fully marine seagrasses which belong to four Family (biology), families (Posidoniaceae, Zosteraceae, Hydrocharitaceae and ...

es. It is usually found in areas with strong surge away from quiet locations.

Ecology

In the kelp forests, ''M. gelatinosus'' is one of the dominant

predators Predation is a biological interaction in which one organism, the predator, kills and eats another organism, its prey. It is one of a family of common feeding behaviours that includes parasitism and micropredation (which usually do not kill ...

along with the starfish '' Stichaster striatus'', '' Luidia magellanica'' and '' Heliaster helianthus'', the fish ''

Pinguipes chilensis ''Pinguipes chilensis'', commonly known as the Chilean sandperch, is a species of ray-finned fish in the family Pinguipedidae. It is found in the southeastern Pacific Ocean off the coasts of Peru and Chile. Description ''P. chilensis'' can grow ...

'', '' Semicossyphus darwini'' and ''

Cheilodactylus variegatus ''Chirodactylus variegatus'', the Peruvian morwong or bilagai, is a species of marine ray-finned fish traditionally regarded as belonging to the family Cheilodactylidae, the members of which are commonly known as morwongs. It is found in the sout ...

'', and the Chilean abalone (''Concholepas concholepas''), a gastropod mollusc. If ''M. gelatinosus'' manages to trap the multiarmed ''H. helianthus'', it everts its stomach over several of the arms of its prey, and these become autotomised as a result of the predation; while the ''M. gelatinosus'' feeds on the shed arms, ''H. helianthus'' makes its escape. In a study in Chile, up to 76% of ''H. helianthus'' were found to have regenerating arms. In a study in Tongoy Bay in north central Chile, ''M. gelatinosus'' was found to be a generalist predator in sand and gravel habitats, but showed a marked preference for the Peruvian scallop (''Argopecten purpuratus'') in

seagrass meadow A seagrass meadow or seagrass bed is an underwater ecosystem formed by seagrasses. Seagrasses are marine (saltwater) plants found in shallow coastal waters and in the brackish waters of estuaries. Seagrasses are flowering plants with stems and ...

s. During the study, the number of scallops declined dramatically when they were heavily harvested commercially over a short period. This caused the starfish to increase its preference for the scallop in both habitats, but it was forced to broaden its diet in the seagrass areas, substituting small

epifauna Fauna (: faunae or faunas) is all of the animal life present in a particular region or time. The corresponding terms for plants and fungi are ''flora'' and ''funga'', respectively. Flora, fauna, funga and other forms of life are collectively r ...

for the missing scallops. The starfish can feed on all sizes of scallop, from in diameter, but particularly preys on the larger specimens. The local fishermen are aware of the competition they face from the starfish for the scallops. In another study, the main prey was the

Chilean sea urchin ''Loxechinus albus'' is an echinoderm of the family Parechinidae, native to coastal southern South America, ranging from Ecuador, along the entire coasts of Peru and Chile, to Argentina, as well as the Falkland Islands. It is the only species in ...

(''Loxechinus albus'') and ''M. gelatinosus'' often selected and pursued its prey with great care. The sea urchin responded to a foraging starfish at a distance of at least a metre by fleeing. This is an effective response where there is vigorous wave action, as the sea urchin gets swept away by the surging water. This sea urchin appeared to be able to distinguish between a foraging ''M. gelatinosus'' and a non-foraging one, taking evasive action in the first case but not in the second. In fact this sea urchin has even been observed touching the starfish when it is not searching for prey.

References

{{Taxonbar, from1=Q18519271, from2=Q2586418 Asteriidae Monotypic echinoderm genera Echinoderms described in 1834 Marine fauna of South America Taxa named by Franz Meyen Taxa named by Addison Emery Verrill Echinoderms of the Pacific Ocean Asteroidea genera