Nautiloidea
Nautiloidea (pronunciation: naw-ti-loi-dea) is a subclass of marine Cephalopods, a group of mollusks that also includes squids, octopuses, and cuttlefish. The subclass is named after the Nautilus, the only extant (living) genus in the group.
Etymology
The term "Nautiloidea" is derived from the Greek words "nautilus," meaning "sailor," and "eidos," meaning "form" or "shape." This name was given due to the nautilus's unique shell shape, which resembles a sailor's ship.
Description
Nautiloidea are characterized by their spiral, chambered shells, which they use for buoyancy. They have a simple nervous system and eyes, and they move by jet propulsion, expelling water from a tube called a Siphuncle.
Evolution
Nautiloidea first appeared in the late Cambrian Period, making them one of the earliest known groups of cephalopods. They were extremely diverse and abundant during the Paleozoic Era, but most lineages became extinct by the end of the Permian Period. Today, only a few species of nautilus remain.
Classification
Nautiloidea is divided into several orders, including Nautilida, Orthocerida, and Discosorida. Each order is further divided into families, genera, and species.
Related Terms
- Cephalopod: The class of marine mollusks that includes nautiloids, squids, octopuses, and cuttlefish.
- Nautilus: The only extant genus of nautiloids.
- Siphuncle: The tube that nautiloids use for jet propulsion.
- Nautilida: An order of nautiloids.
- Orthocerida: An extinct order of nautiloids.
- Discosorida: An extinct order of nautiloids.
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