Pentagonaster (starfish)
Pentagonaster is a genus of sea stars belonging to the family Oreasteridae. These starfish are characterized by their pentagonal shape, appearing almost like a five-sided disc with very short, blunt arms that are broadly connected to the central disc.
Description
Pentagonaster species typically have a rigid, tiled appearance on their aboral (upper) surface, formed by numerous small plates or ossicles. These plates are often covered in granules or small spines. The overall texture of the body is typically smooth to the touch despite the presence of these features. Coloration varies among species but often includes shades of red, orange, brown, and yellow. The madreporite, a porous plate used for water vascular system regulation, is usually visible on the aboral surface. The oral (lower) surface contains the mouth at the center and ambulacral grooves extending along each arm, housing the tube feet used for locomotion and feeding.
Distribution and Habitat
Pentagonaster starfish are found in various marine environments, including tropical and temperate waters. They typically inhabit shallow to moderately deep waters, often residing on sandy or rocky substrates. Specific distribution and habitat preferences vary depending on the particular species within the genus.
Ecology and Behavior
Pentagonaster are generally considered to be scavengers and detritivores, feeding on organic matter and small invertebrates found on the seafloor. They use their tube feet to move and capture food. Little is known about the specific reproductive strategies of all Pentagonaster species, but like many starfish, they likely reproduce both sexually and asexually, with sexual reproduction involving the release of eggs and sperm into the water column for fertilization.
Taxonomy
The genus Pentagonaster is classified within the family Oreasteridae, which includes other cushion star and sea star species with similar body plans and characteristics. The classification of species within the genus has been subject to revision and further research may be needed to clarify taxonomic relationships.