- habit
- habitat
- habitus
- hadal
- haploid
- hatching
- head
- heart
- heathland
- herbivore
- herbivorous
- hermaphrodite
- Hermaphroditism
- hermit crabs
- herpetology
- heteracanth
- heterocercal
- heterogamety
- heteromorphic
- heterotroph
- heterotrophic
- heterozygous
- hexagonal
- hibernate
- holarctic distribution
- holistic
- holobranch
- Holocene
- holotropical distribution
- holotype
- homeotherms
- homocercal
- homology
- honeycombed
- hook
- hormone
- horn
- host
- humeral
- hyaline
- hybrid
- hydrobiological
- hydroids
- hydrology
- hydrozoans
- hyoid
- hypaxial
- hyper saline
- hyperborean
- hypertrophied
- hypobranchial
- hypural
- hypural plate