- habit
- habitat
- hadal
- hatching
- head
- heart
- herbivore
- heterocercal
- hexagonal
- hibernating
- holarctic distribution
- holobranch
- holotropical distribution
- holotype
- homocercal
- hook
- horn
- host
- humantin
- humeral
- hyaline
- hybrid
- hydroids
- hydrology
- hydrozoans
- hyoid
- hypaxial
- hyper saline
- hyperborean
- hyperid
- hypobranchial
- hypoprion
- hypotremata
- hypural plate