Aglaopheniidae Family of Hydrozoa
San Diego Aglaophenia, Aglaophenia diegensis. A representative of the Aglaopheniidae Family of Hydrozoa.
Phylogeny: Aglaophenid Hydroids of the Aglaopheniidae Family, like Sea Anemones and Jellyfish, belong to the phylum Cnidaria. They are in the subphylum Medusazoa, the class Hydrozoa, the subclass Hydroidolina, the order Leptothecata, and the superfamily Plumularioidea. The Aglaopheniidae Family is one of seven families within this superfamily. The Aglaopheniidae Family is large and contains fourteen genera and two hundred sixty-nine species. The name Aglaopheniidae comes from the Greek words meaning something like “shining appearance” or “splendid display”. This refers to the delicate and sometimes iridescent appearance of these hydroids.
Morphology: Aglaophenid Hydroids look like plants, but are benthic colonial hydroids that are generally characterized by their pinnate (feather-like) shape, though some are fan-shaped. They possess a chitinous, often branched skeleton (perisarc) with specialized feeding polyps (gastrozooids) and defensive, stinging polyps () arranged on side branches (hydrocladia).on key synapomorphies, particularly the structure of the gonothecae.
Habitat and Distribution: Aglaophenid Hydroids are usually found attached to hard substrates or algae. They live in the intertidal zone and to depths of 519 m (1,702 feet). Aglaophenid Hydroids are found worldwide in temperate to tropical seas. At least thirteen species from this family are found in Mexican waters.
Reproduction: Aglaophenid Hydroids reproduce asexually through budding and fragmentation. They also reproduce sexually. Individual colonies are gonochoric (male or female for life). The gonophores are housed with specialized protective structures called corbulae. The males release sperm into the water which find their way to the female’s gonophores. Upon fertilization, embryos develop into planula larvae within the female’s gonophore. Within a few days the planula settles on a suitable substrate to form a primary polyp. Unlike most hydrozoans, Aglaophenid Hydroids typically lack a free-swimming medusa stage.
Ecosystem Roles: Aglaophenid Hydroids are suspension feeders that use their tentacles to capture plankton from the surrounding water. They generate ciliary microcurrents to transport the food to their mouth. Some species within the family are zooxanthellate, meaning that they have a symbiotic relationship with single-cell dinoflagellates, known as zooxanthellae. The zooxanthellae produce energy, during daylight, by means of photosynthesis. This energy is passed along to their hosts, sometimes providing up to 90% of the host’s total energy needs. In return, the host provides nutrients, carbon dioxide, and a secure, sunlit, platform for the zooxanthellae. Aglaophenid Hydroids are generally prey for nudibranchs and other gastropods. Some species host commensal shrimp that seek protection among the hydroid’s stinging cells. Thick colonies of Aglaophenid Hydroids provide protection for amphipods and other small invertebrates.