1. Botany, Entomology Herpetology, mammalogy, and ornithology.

2. 3 Botany, Entomology Herpetology, mammalogy, and ornithology.

3. Most marine Biologists choose a specialty field such as phycology, ichthyology, invertebrate zoology, marine mammalogy, fishery biology, marine biotechnology, marine microbiology, or marine ecology.Specialization in studying a particular species also is common.