- habit
- habitat
- hadal
- hairfin
- hairtail
- harpacticoids
- hatching
- head
- heart
- Hebrides Islands
- herbivore
- hermaphrodite
- heterocercal
- heteromi
- hexagonal
- hibernating
- holarctic distribution
- holobranch
- holocentre
- holothurians
- holotropical distribution
- holotype
- homocercal
- homoptera
- hook
- horn
- host
- humantin
- humeral
- hyaline
- hybrid
- hydroids
- hydrology
- hydrozoans
- hyoid
- hypaxial
- hyper saline
- hyperborean
- hyperid
- hypobranchial
- hypoprion
- hypotremata
- hypural plate