SEMIAQUATIC
semiaquatic, subaquatic
(adjective) partially aquatic; living or growing partly on land and partly in water; “a marginal subaquatic flora”
amphibiotic, semiaquatic
(adjective) having an aquatic early or larval form and a terrestrial adult form
Source: WordNet® 3.1
Etymology
Adjective
semiaquatic (not comparable)
(of animals) Spending part of the life cycle underwater. Also, spending a significant proportion of its time in both terrestrial and aquatic environments.
(of plants) Having the roots partially or entirely underwater.
Source: Wiktionary