Heliaster
Heliaster is a genus of starfish belonging to the family Heliasteridae. Commonly known as the “sun stars” or “sea daisies,” these striking echinoderms are characterized by their distinctive radial symmetry and numerous arms.
Characteristics
Heliaster species exhibit remarkable variations in size and arm number, ranging from a few inches to over a foot in diameter. They are generally brightly colored, displaying hues of orange, red, yellow, or purple. Their most distinguishing feature is the presence of numerous arms, typically 10 to 15, radiating outwards from a central disc. These arms are often flattened and may be branched or divided, creating a starburst appearance. Each arm is lined with rows of tube feet, which aid in locomotion and feeding.
Habitat and Distribution
Heliaster species are found primarily in the eastern Pacific Ocean, inhabiting a variety of marine environments. They are often found in shallow waters, particularly along rocky shores, kelp forests, and sandy bottoms. Some species may occur in deeper waters, at depths exceeding 100 meters. Their distribution extends from California in the north to Peru in the south.
Feeding
Heliaster are carnivorous, feeding primarily on a diet of bivalves, gastropods, crustaceans, and other small invertebrates. They use their numerous arms to capture prey, employing tube feet to pry open shells and engulf their food. Some species have been observed to exhibit communal feeding behavior, with multiple individuals converging on a single prey item.
Reproduction
Heliaster species reproduce sexually, releasing sperm and eggs into the water column for external fertilization. The resulting larvae undergo a series of developmental stages before metamorphosing into juvenile starfish. They are known to be prolific breeders, with some species capable of producing millions of eggs per year.
Notable Species
- Heliaster helianthus: The most commonly known species, often referred to as the "California sun star," is found along the Pacific coast of North America.
- Heliaster kubiniji: A smaller species with a distinctive orange-red coloration, known from the Galapagos Islands.
- Heliaster elegans: Found off the coast of Chile, this species is characterized by its numerous, branched arms.