Nautilus
The nautilus (pronounced /ˈnɔːtɪlʌs/) is a group of cephalopods that belong to the family Nautilidae. They are the only living members of the suborder Nautilina, which diverged from other cephalopods (such as squid, octopus, and cuttlefish) about 500 million years ago. There are six extant species of nautilus, all of which are found in the Indo-Pacific region.
Common Names
Nautilus are commonly referred to as "living fossils" because their form has changed very little over millions of years. They are also sometimes called "chambered nautilus" or "ship of pearl" due to their distinctive spiral shell.
Characteristics
Nautilus are characterized by their unique external shell, which is divided into a series of chambers connected by a tube called the siphuncle. The animal lives in the outermost chamber, and the other chambers are filled with gas, which helps to regulate buoyancy. The shell is made of nacre, the same material that creates pearls in oysters. Nautilus shells can be up to 10 inches (25 cm) in diameter and have a distinctive, swirling pattern.
Unlike most other cephalopods, nautilus have a simple eye structure that can only detect light and darkness. They have around 90 tentacles, which are not retractable like those of squid and octopus. Nautilus are also carnivorous, feeding on crustaceans, fish, and other cephalopods.
Environments
Nautilus are found in the deep waters of the Indo-Pacific region, typically at depths of 100-1,000 meters. They are active at night and spend their days resting in crevices or under coral reefs. Their preferred habitat is areas with strong currents and a plentiful supply of food.
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