Stylasteridae

Stylasteridae is a family of colonial marine hydrozoans in the class Hydrozoa, commonly known as lace corals or stylasterid corals. They secrete a calcium carbonate skeleton and form intricate, delicate structures that resemble true corals, but they are not part of the Scleractinia. The group is diverse, with many species differing in colony shape and polyp arrangement.

Colonies grow as branching or vase-like forms, composed of small calcareous cups called corallites. Within the skeleton, specialized polyps include gastrozooids for feeding and dactylozooids for defense. This division of labor among polyps gives stylasterids their characteristic, lace-like appearance. The corallum provides shelter and habitat for various small invertebrates.

Stylasteridae have a wide global distribution, occurring from shallow coastal waters to deep-sea environments on hard substrates such as rocks and reefs. They are particularly diverse in the Indo-Pacific region and contribute to complex benthic ecosystems, including some mesophotic and deep-water communities.

Reproduction in stylasterids typically involves gonophores produced on the colonial skeleton. Many species have reduced or absent free-swimming medusae, with sexual reproduction yielding planula larvae that settle to form new colonies. Some species brood developing young within the colony. Reproductive strategies can be dioecious or monoecious, contributing to genetic diversity within populations.

Taxonomically, Stylasteridae is anchored by the genus Stylaster, the type genus of the family. The group contains numerous genera and species, and their calcareous skeletons fossilize well, providing important records for studies of hydrozoan evolution and ancient reef systems.