Hierarchy classification:

1. top of the aat hierarchies
2. Agents Facet
3. Living Organisms (hierarchy name)
4. living organisms (entities)
5. Eukaryota (domain)
6. Animalia (kingdom)
7. Cnidaria (phylum)
8. Hydrozoa (class)

Narrower term/s

• Hydridae (family)[+]
  • Hydra (genus)

Anotations

Scope note:

Members of an order containing marine invertebrates that are bell-shaped with gonads on the stomach or sides of manubrium, sensory structures consisting of pigmented eyespots (ocelli), a skeleton, if present, that lacks a cup (hydrotheca) into which the polyp may withdraw. A few species have a calcareous exoskeleton. They are most abundant in bays and shallow coastal waters.