Heliasteridae Family of Starfish

Gulf Sun Star, Heliaster kubiniji. A representative of the Heliasteridae Family of  Starfish.

Phylogeny:  The Heliasterid Sun Stars are members of the Heliasterid Family of Sun Stars and are in the Phylum Echinodermata, a large Phylum that includes Brittle Stars, Sea Cucumbers, Sea Lulies, Starfish and Urchins. The Echinodermata are of great scientific interest because, via fossil records, they have been dated to the Cambrian Age (over 500,000,000 years ago) with 7,000 living and 13,000 extinct individual species. There are one thousand five hundred species in the Heliasterid Family. They are in the Class Astgeroidea and the Order Forcipulatida.

Distribution:   Heliasterid Sun Stars have a limited distribution being found in the Eastern Pacific, Southern South America, and Antarctica. This Family only consists of two genera and seven species of which three species are found along the Pacific Coast of Mexico. They are found from intertidal zones to depths of 9,150 m (30,000 feet) on gravel, mud, rock and sand substrate. 

Morphology:  Heliasterid Sun Stars are medium to large sea stars, with multiple arms, wide central discs and long thin arms (although they may be stout in some species). They all have flattened flexible bodies that are covered with colored skin. They are characterized by a larval stage with bilateral symmetry and an adult stage with 5-rayed radial symmetry. They have from 9 to more than 50 arms. They lack a sharp differentiation between the ventral and dorsal sides of the disc and arms. They have crossed pedicellariae (tiny pincers) on their dorsal surface, as well as single or grouped spines. They have a unique water-vascular system that uses hydraulic power to operate a multitude of tined tube feet that are used in locomotion and food capture. Some feed via inserting the stomach out through the mouth surrounding the prey, secreting enzymes to digest the food and then retracting the stomach when finished eating. These sea stars may be brown, gray, pink, purplish, yellow or white in color, and are either solid, banded or mottled in pattern. Heliasterid Sun Stars can reach a maximum of 30 cm (11.8 inches) in diameter.

Ecosystems Role:  Heliasterid feed as scavengers or predators consuming barnacles, bivalves, euphausids, fish, gastropods, isopods, sponges, and other sea stars. In turn they are preyed upon by shore birds, crabs, fish and other sea stars. The Heliasterid Sun Stars have undergone a significant decline in populations in the Temperate Eastern Pacific since 2013 which have been as much as 80% for some species. Many attribute these losses to the Sea Star Wasting Disease, a Densovirus (Parvoviridae). Others believe other factors may be in play such as environmental stressors. Only recently have some species begun to recover, and only in certain areas.