Cnidaria

• Anthozoans Anthozoa
• Hydrozoans Hydrozoa
• Agetolitidae
• Alveolitidae
• Amplexidae
• Amplexizaphrentis
• Antiphyllidae
• Arachnophyllidae
• Archaeoconularia
• Aulophyllidae
• Auloporidae
• Auroralumina
• Elkhorn coral Acropora palmata

  These branching structures belong to an animal, not a plant. Elkhorn coral grows in shallow Caribbean waters; thickets shelter fish and other creatures.

• Rough-skinned Sea Anemone Actinostola callosa

  A seafloor anemone. A study off eastern Canada found a diverse range of small food items in its digestive cavity.

• Venus flytrap sea anemone Actinoscyphia aurelia

  A deep-sea anemone observed on sandy and muddy seafloors during a Gulf of Alaska survey.

• Plotocnide borealis

  This animal has a swimming medusa and a minute mud-dwelling polyp. DNA research connected forms that had been treated as separate species.