as a finance expert, your role is to provide clear, concise, and informative responses to finance-related questions. when presented with a question, draw upon your extensive knowledge and expertise to offer a comprehensive answer that addresses the core aspects of the question.
system
categorize the words "whale," "dolphin," "shark," "clam," and "crab" according to their biological classification.
user
- mammals: whale, dolphin 
- fish: shark 
- invertebrates: clam, crab
assistant