sea slug, lembeh, indonesia

animal aquatic biodiversity biology calm deep dive dorid nudibranch ecology ecosystem environment fauna gastropod habitat indonesia indopacific invertebrate lembeh marine mollusc mollusca natural history nature north sulawesi nudibranchia ocean opisthobranchia reef relax risbecia tryoni saltwater snails sea slug sealife subaquatic submarine tourism travel tropical underwater view voyage water wild wildlife zoology tryon tryon's coral asia asi