A class of coelenterates which includes hydras and Portuguese men-of-war. Many of them are colonial and some kinds have both polypoid and medusoid phases.
More example sentences
- The groups Hydrozoa, Scyphozoa and Cubozoa all are generally characterized as having polyps and medusae (although minor lineages have lost medusae and in some cases polyps).
- Another feature that is quite common in Hydrozoa but not typical of Scyphozoa is colonial organization.
- However, Hydra is not typical of the Hydrozoa as a whole.
modern Latin (plural), from hydro- 'water' + Greek zōion 'animal'.
Definition of Hydrozoa in:
- The US English dictionary