Fragile Sand Star, Astropecten fragilis
Fragile Sand Star, Astropecten fragilis. Sea star collected off the extreme southwest coast of Baja California Sur, November 2012. Pictured stars diameter: 19 cm (7.5 inches).
Phylogeny: The Fragile Sand Star, Astropecten fragilis (Verrill, 1867), is a member of the Astropectinidae Family of Sea Stars. The genus Astropecten is one of twenty-six genera in the Astropectinidae Family, and there are one hundred four species in the Astropecten genus. They are known in Mexico as Estrella Frágil. The genus name Astropecten comes from the Greek word for “star” and the Latin word for “comb”. This combination refers to the comb-like plates along the arms of there sea stars.
Morphology: Fragile Sand Stars are somewhat flattened and have only a moderately wide central disc. The five arms are narrow, tapering, and about 6.5 times longer than the radius of the disc. The plates along the margin of the arms and disk are very obvious. The aboral surface of these stars is brown to gray-brown in color, and the marginal plates are lighter in color. Fragile Sand Stars have are a maximum of 25 cm (10 inches) in diameter.
Habitat and Distribution: Fragile Sand Stars are found on sand. They live in the lower intertidal zone and to depths up to 203 M (666 feet). They are a subtropical to tropical eastern Pacific species. In Mexican waters they range from Isla San Pedro Nolasco, Sonora, to Guatemala. They are absent from the west coast of the Baja Peninsula.
Diet: Fragile Sand Stars are a poorly documented and understood species. There is limited information available regarding the diet of this species. Other species in the Astropectinidae Family prey on bivalves, carrion, crustaceans, detritus, gastropods, other sea stars and sea urchins. All prey is swallowed whole as they do not have the ability to extrude their stomachs.
Predators: Fragile Sand Stars are a poorly studied and understood species. There is little documentation regarding predation of this species. Other species in this family are prey for small crabs and small fish.
Reproduction: Fragile Sea Stars are gonochoric (male or female for life). Reproduction may be asexual, by both regeneration and clonal, or sexual. Sexual reproduction involves broadcast spawning with external fertilization. The fertilized eggs hatch into planktonic larvae and later metamorphose into pentamerous juveniles which develop into young sea stars with stubby arms.
Ecosystem Interactions: Fragile Sand Stars are a poorly studied and understood species. The ecosystem interactions of this species have not been documented. Some species in Astropecten Genus have commensal relationships with polychaete worms. Also, endoparasitic crustaceans of the genus Dendrogaster parasitize species in the Astropecten genus.
Human Interactions: Fragile Sand Stars have little direct impact on human activities. From a conservation perspective they have not been formally evaluated however they are fairly common with a relatively wide distribution and should be consider to be of Least Concern
Synonyms: None