Hydrozoans are small, predatory jellyfish and siphonophores with stinging cells belonging to the phylum Cnidaria with larger jellyfish, coral, and sea-anemones. Most hydrozoans have an alternation of generations which includes a sessile, benthic polyp stage, and a plankktonic medusa, jellyfish stage. Siphonophores are colonial hydrozoans that are composed of both medusa and polyp stages.

Siphonophores

Blackfordia spp.

Liriope tetraphylla

Cunia octonaria