# Pond: Fishes - [[Bluefin tuna's body stays warm but its heart does not]] - [[Tuna never stop swimming]] - [[Blue whale can interbreed with fin whales and have blue-fin whale babies]] - [[Opah is the only fully warm-blooded fish]] - [[Sharks feed on whale carcass]] - [[Blue whales only feed on the most nutritious patches of krill to save energy]]