 Members of the Caluromyinae are essentially frugivorous; whereas the lutrine opossum and Patagonian opossum primarily feed on other animals.The water opossum or yapok ("Chironectes minimus") is particularly unusual, as it is the only living semi-aquatic marsupial, using its webbed hindlimbs to dive in search of freshwater mollusks and crayfish.The extinct "Thylophorops", the largest known opossum at 4–7 kg, was a macropredator.