Nautilidae
The Nautilidae are a family of cephalopods that are the only surviving members of the order Nautilida. They are commonly called nautiluses, chambered nautiluses, or simply nautilus. They are characterized by their distinctive coiled shell, which is divided into chambers. These cephalopods are found in the Indo-Pacific region, and are among the most ancient living cephalopod lineages, dating back to the Late Paleozoic era.
Common Names
The common name for the Nautilidae is "nautilus". They are also known as "chambered nautiluses" because of the distinctive chambers in their shells. Sometimes they are referred to simply as "nautilus".
Characteristics
Nautilidae have a number of distinctive characteristics:
- Coiled shell: The most notable feature of nautiluses is their coiled shell, which is divided into chambers. The animal lives in the outermost chamber, while the other chambers are filled with gas, which helps the nautilus regulate its buoyancy.
- External shell: Unlike most cephalopods, nautiluses have an external shell, which provides protection from predators.
- Simple eyes: Nautiluses have simple eyes that are not as sophisticated as the eyes of other cephalopods. They lack the complex lenses and retinas found in the eyes of squid, octopus, and cuttlefish.
- Mantle: The mantle is a muscular organ that surrounds the body of the nautilus. It is responsible for jet propulsion, which allows the nautilus to move quickly through the water.
- Arms and tentacles: Nautiluses have 90 small, retractable tentacles that they use to capture prey.
Environment
Nautilidae are found in the Indo-Pacific region. They live in deep water, typically at depths of 100 to 500 meters. Nautiluses are nocturnal, and they feed on crustaceans, fish, and other small animals.