Oreasteridae Family of Sea Stars
Two Sea Stars of the Oreasteridae Family can be found in this website:
Phylogeny: Oreasterid Sea Stars of the Oreasteridae Family are in the phylum Echinodermata, which is a large phylum that includes brittle stars, sea cucumbers, sea lilies, sea stars and sea urchins. They are in the subphylum Asterozoa and the class Asteroidea. Asteroideans are characterized by having a flattened, star shape, with a central disk, surrounded by multiple (5 to 40) radiating arms (or rays). Ophidiasterid Sea Stars are in the subclass Ambuloasteroidea, the infraclass Neoasteroidea, the superorder Valvatacea, and the order Valvatida. The Oreasteridae Family is one of fifteen families in this order. The Oreasteridae Family contains eighteen genera and sixty-six species. The name Oreasteridae comes from the Greek words meaning “mountain star”, referring to their dome-shaped profiles. This profile also gives rise to their common name of Cushion Stars
Morphology: Oreasterid Sea Stars generally have five arms, with two rows of tube feet on the underside of each arm. Sea Stars in this Family have large central disks relative to the length of their arms. In some species, these stars look more like pentagons than stars. These stars are dome shaped in profile and have stiff bodies. Cushion Stars have well developed marginal plates, but the plates are not always obvious. They have thick skin, with tubercles or granules. These stars have tube feet with terminal disks that have spicules in their walls. The pedicellariae are sunken and may be bivalve or forcipulate, or resemble split granules. Cushion Stars are often brightly colored and can reach up to 50 cm (20 inches) in diameter.
Habitat and Distribution: Oreasterid Sea Stars are found on coral, mud, rock, and sand substrates. They are often associated with sea grass beds or mangroves. They live intertidally, and to depths up to 220 m (720 feet). Oreasterid Sea Stars are found worldwide in tropical to temperate seas. At least three species are found in Mexican waters.
Reproduction: Oreasterid Sea Stars are gonochoric (male or female for life). They reproduce sexually, through broadcast spawning, with external fertilization. The fertilized eggs develop into planktonic larvae. They can also reproduce asexually through fission, and for some species, through larval cloning.
Ecosystem Roles: Oreasterid Sea Stars feed on algae, ascidians, bryozoans, corals, sponges and sea urchins. In turn they are preyed upon by crabs, shrimp and other sea stars.