The greater argonaut (Argonauta argo) is a cephalopod and a species of pelagic octopus also known as a paper nautilus.

Greater Argonaut

The greater argonaut (Argonauta argo) is a cephalopod and a species of pelagic octopus also known as…

"Cephalopoda is a class of mollusks, the highest in organization of the division of the animal kingdom. To this class belong the Nautili, Squids, Cuttle-fish, etc. The Cephalopoda receive their name from having organs of prehension and locomotion attached to the head, an arrangement toward which a gradual approach may be traced in the highest gasteropod mollusks."—(Charles Leonard-Stuart, 1911)

Cephalopoda

"Cephalopoda is a class of mollusks, the highest in organization of the division of the animal kingdom.…

"Has the body eight inches long, and the longest tentacles nearly three feet." — Goodrich, 1859

Bonelli's Cheiroteuthis

"Has the body eight inches long, and the longest tentacles nearly three feet." — Goodrich, 1859

"In one genera [of the <em>Octopodidae</em> family] the arms are completely united in their whole extent by a thin membrane."

Cirrhoteuthis Mulleri (Eschricht)

"In one genera [of the Octopodidae family] the arms are completely united in their whole extent…

The body of the cuttlefish is soft and covered only with a leathery skin. Its eight arms are very long.

Cuttlefish

The body of the cuttlefish is soft and covered only with a leathery skin. Its eight arms are very long.

Cephalopods are the most highly organized Molluscs. The head is distinct, carrying two large globular eyes, and having the mouth in its center.

Cuttlefish

Cephalopods are the most highly organized Molluscs. The head is distinct, carrying two large globular…

A fish with eight arms.

Cuttlefish

A fish with eight arms.

The Common Cuttlefish (Sepia officinalis) is a mollusc in the Sepiidae family of cephalopods.

Common Cuttlefish

The Common Cuttlefish (Sepia officinalis) is a mollusc in the Sepiidae family of cephalopods.

A cuttle fish.

Cuttlefish

A cuttle fish.

"Giant Squid (Architeuthis dux). (From Report of U.S. Fish Commission, 1884.)-Whitney, 1902

Giant Squid

"Giant Squid (Architeuthis dux). (From Report of U.S. Fish Commission, 1884.)-Whitney, 1902

"The Common Calmar or Squid. They propel themselves backward through the water with great velocity, driving back the water by means of their funnel."

Loligo Gahi (d'Orbigny)

"The Common Calmar or Squid. They propel themselves backward through the water with great velocity,…

"The Common Calmar or Squid. They propel themselves backward through the water with great velocity, driving back the water by means of their funnel."

Loligo Vulgaris, with its pen, or internal bone (Lamarck)

"The Common Calmar or Squid. They propel themselves backward through the water with great velocity,…

Chambered nautilus, showing chambers with soft body in outer chamber. It is closely related to the squids and cuttlefishes, but has the body enclosed in a flat-spiral shell.

Nautilus

Chambered nautilus, showing chambers with soft body in outer chamber. It is closely related to the squids…

The paper-nautilus is closely related to the Octopus.

Paper Nautilus

The paper-nautilus is closely related to the Octopus.

Octopus, a mollusk related to the squid. It has eight arms with suckers, arranged around a central soft, baggy body.

Octopus

Octopus, a mollusk related to the squid. It has eight arms with suckers, arranged around a central soft,…

Octopus, a mollusk related to the squid. It has eight arms with suckers, arranged around a central soft, baggy body.

Octopus

Octopus, a mollusk related to the squid. It has eight arms with suckers, arranged around a central soft,…

As the name indicates, the octopus has eight arms instead of ten, as in the squids and cuttles.

Octopus

As the name indicates, the octopus has eight arms instead of ten, as in the squids and cuttles.

Part of the cephalopod group. The name cephalopod is derived from two greek words which mean feet on head.

Octopus

Part of the cephalopod group. The name cephalopod is derived from two greek words which mean feet on…

"A very ugly-looking creature, which belongs to the <em>Octopodidae</em> family, is the Octopus."

Octopus Brevipes (d'Orbigny)

"A very ugly-looking creature, which belongs to the Octopodidae family, is the Octopus."

"A very ugly-looking creature, which belongs to the <em>Octopodidae</em> family, is the Octopus."

Octopus Horridus (d'Orbigny)

"A very ugly-looking creature, which belongs to the Octopodidae family, is the Octopus."

"A very ugly-looking creature, which belongs to the <em>Octopodidae</em> family, is the Octopus."

Octopus Macropus (Risso)

"A very ugly-looking creature, which belongs to the Octopodidae family, is the Octopus."

"A very ugly-looking creature, which belongs to the <em>Octopodidae</em> family, is the Octopus."

Octopus Vulgaris (Lamarck)

"A very ugly-looking creature, which belongs to the Octopodidae family, is the Octopus."

This creature, belonging to the <em>Octopodidae</em> family, "changes its color under any exertion, so that the animal at rest and in motion are two different beings."

Pinnoctopus Cordiiformis (Q. & G.)

This creature, belonging to the Octopodidae family, "changes its color under any exertion,…

"Cuttlefish are probably the most interesting animals of [the cephalopoda] order. They live for five or six years, and lay eggs, which are large and generally found in clusters, and are known to fishermen as sea-grapes."

Sepia Officinalis (Linnaeus)

"Cuttlefish are probably the most interesting animals of [the cephalopoda] order. They live for five…

An upclose view of the arm of a Sepia Tuberculosa.

Arm of Sepia Tuberculosa (Lamarck)

An upclose view of the arm of a Sepia Tuberculosa.

The squid is the best example of the cephalopod group. It is abundant along the Atlantic coast. Squids swim in schools and feed on young herring and mackerel.

Squid

The squid is the best example of the cephalopod group. It is abundant along the Atlantic coast. Squids…

A modern decapod cephalopod with remnant of internal shell only.

European Squid

A modern decapod cephalopod with remnant of internal shell only.

"Its length from tail to the end of the tentacles is six feet. The two largest of these are furnished with suckers and hooks, which enable the animal to seize its prey with a powerful grip." &mdash; Goodrich, 1859

Hooked squid

"Its length from tail to the end of the tentacles is six feet. The two largest of these are furnished…