Stylaster

Stylaster is a genus of hydrocorals, belonging to the family Stylasteridae within the order Hydroida. These are not true corals, but rather hydrozoans that secrete a calcareous exoskeleton.

Stylaster hydrocorals are characterized by their branching, often brightly colored, colonies. These colonies are composed of numerous tiny polyps embedded within the rigid skeleton. Unlike true corals (Anthozoa), Stylaster species lack internal skeletal elements called septa.

Key features of Stylaster include:

• Hydrocoral Nature: They are hydrozoans, not true corals.
• Calcareous Exoskeleton: A hard, external skeleton provides structural support.
• Polymorphic Polyps: The colony contains different types of polyps with specialized functions, such as feeding (gastrozooids) and defense (dactylozooids).
• Gastrovascular System: A network of canals connecting the polyps allows for nutrient distribution throughout the colony.
• Habitat: They are commonly found in deep-sea environments and rocky reefs, often in areas with strong currents.
• Reproduction: Stylaster species reproduce both sexually and asexually.
• Taxonomy: The classification of species within the genus Stylaster can be complex and has been subject to revision.

Stylaster species play a role in structuring deep-sea ecosystems and can serve as habitat for other marine organisms. Their sensitivity to environmental changes, such as ocean acidification and bottom trawling, makes them important indicators of ocean health.