a fossil cephalopod similar to the nautilisk.

Ammonite

a fossil cephalopod similar to the nautilisk.

a fossil cephalopod similar to the nautilisk.

Ammonite

a fossil cephalopod similar to the nautilisk.

a fossil cephalopod similar to the nautilisk.

Ammonite

a fossil cephalopod similar to the nautilisk.

"Goniatites henslowi. GONIOTITES. A genus of fossil ammonites, giving name to the family Goniatitidae, having a discoid shell with angulated lobed sutures." -Whitney, 1911

Ammonoid

"Goniatites henslowi. GONIOTITES. A genus of fossil ammonites, giving name to the family Goniatitidae,…

"A genus of fossil terebranchiate cephalopods, of the family Ammonitidæ, or made the type of a special family Ancyloceratidæ."-Whitney, 1902

Ancyloceras

"A genus of fossil terebranchiate cephalopods, of the family Ammonitidæ, or made the type of a…

The paper nautilus or argonaut, a cuttlefish.

Argonaut

The paper nautilus or argonaut, a cuttlefish.

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…

"Male of Argonauta showing "hectocotylus" arm." -Thomson, 1916

Argonauta

"Male of Argonauta showing "hectocotylus" arm." -Thomson, 1916

The cephalopods are the mollusk class Cephalopoda characterized by bilateral body symmetry, a prominent head, and a modification of the mollusk foot, a muscular hydrostat, into the form of arms or tentacles. Teuthology, a branch of malacology, is the study of cephalopods. The class contains two extant subclasses. In the Coleoidea, the mollusk shell has been internalized or is absent; this subclass includes the octopuses, squid, and cuttlefish. In the Nautiloidea the shell remains; this subclass includes the nautilus. About 786 distinct living species of cephalopods have been identified. Two important extinct taxa are Ammonoidea, the ammonites, and Belemnoidea, the belemnites Cephalopods are found in all the oceans of Earth, at all depths. None of them can tolerate freshwater, but a few species tolerate more or less brackish water.

Cephalopod

The cephalopods are the mollusk class Cephalopoda characterized by bilateral body symmetry, a prominent…

A simple straight-shelled cephalopod. Where the shell has been removed, the straight sutures are shown.

Cephalopod

A simple straight-shelled cephalopod. Where the shell has been removed, the straight sutures are shown.

"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.…

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…

The side view of Sepia officinalis, or the common cuttlefish.

Cuttlefish

The side view of Sepia officinalis, or the common cuttlefish.

"Diagram of circulatory and excretory systems in a Decapod-like Sepia. 1, Gill; 2, renal sac; 3, afferent branchial vessel; 4, branchial heart; 5, abdominal vein; 6, heart; 7, viscero-pericardial sac (body cavity); 8, genital organ; 9, posterior aorta; 10, "auricle"; 11, glandular appendix of branchial heart; 12, renal appendices of branchial vein; 13, external aperure of kidney; 14, vena cava; 15, anterior aorta; 16, bifurcation of vena cava; 17, reno-pericardial aperture." -Thomson, 1916

Cuttlefish Circulatory and Excretory Systems

"Diagram of circulatory and excretory systems in a Decapod-like Sepia. 1, Gill; 2, renal sac; 3, afferent…

"Bunch of Sepia eggs attached to plant." -Thomson, 1916

Cuttlefish Eggs

"Bunch of Sepia eggs attached to plant." -Thomson, 1916

"Diagram of the structure of Sepia. a., Eight short arms around mouth; l.a., one of the two long arms; b., beak of the mouth; c.g., cerebral ganglia, with commissures to the others; E., eye; g., gullet; d.g., digestive gland (the "salivary glands" are not represented); st., stomach; a., anus; sh., shell-sac with sepiostaire; k., kidney; R., reproductive organ; br.h., branchial heart; g., a gill; i.b., ink-bag; m.c., mantle cavity; f., funnel." -Thomson, 1916

Cuttlefish Structure

"Diagram of the structure of Sepia. a., Eight short arms around mouth; l.a., one of the two long 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.

The nautilus is a true mollusc. (a) mantle; (o) eye; (t) tentacles; (f) funnel.

Nautilus

The nautilus is a true mollusc. (a) mantle; (o) eye; (t) tentacles; (f) funnel.

"Section of the shell of Nautilus pompilius, showing the septa (s, s), the septal necks (s. n., s. n.), the siphuncle (si, represented by dotted lines), and the large body-chamber (ch)." -Parker, 1900

Chambered Nautilus

"Section of the shell of Nautilus pompilius, showing the septa (s, s), the septal necks (s. n., s. n.),…

The paper-nautilus is closely related to the Octopus.

Paper Nautilus

The paper-nautilus is closely related to the Octopus.

The cephalopod, the paper nautilus (female).

Paper Nautilus

The cephalopod, the paper nautilus (female).

"The Devil-fish (Octopus). A, at rest; B, swimming. a, arms, with suckers on the inner aspect; e, eye; s, siphon or funnel." -Galloway, 1915

Octopus

"The Devil-fish (Octopus). A, at rest; B, swimming. a, arms, with suckers on the inner aspect; e, eye;…

Graneledone verrucosa is a species of cephalopods in the Octopodidae family of octopuses.

Octopus

Graneledone verrucosa is a species of cephalopods in the Octopodidae family of octopuses.

"The Paper Nautilus (Argonauta argo). e, eye; m, mouth; f, siphon; sh, shell; t, tentacles." -Galloway, 1915

Paper Nautilus

"The Paper Nautilus (Argonauta argo). e, eye; m, mouth; f, siphon; sh, shell; t, tentacles." -Galloway,…

The Pearly Nautilus (Nautilus Pompilius) is the only living representative of a unique form of cephalopod, recorded in fossils for over 500 million years. The shell, pearly and beautifully colored, is spirally formed and consists of a series of chambers separated by curved cross plates thus exemplifies the "chambered shell". The nautilus is a bottom feeder on Crustaceans, usually in deep water.

Pearly Nautilus

The Pearly Nautilus (Nautilus Pompilius) is the only living representative of a unique form of cephalopod,…

Scaphites equalis is a species of extinct cephalopods that thrived during the Cretaceous period.

Scaphites

Scaphites equalis is a species of extinct cephalopods that thrived during the Cretaceous period.

"Spirula peronii, lateral view. d, terminal sucker; f, funnel; s1, s2, projecting portions of the shell, the internal part of which is indicated by dotted lines." -Parker, 1900

Spirula Peronii

"Spirula peronii, lateral view. d, terminal sucker; f, funnel; s1, s2, projecting portions of the shell,…

The Atlantic Bobtail (Sepiola atlantica) is a cephalopod in the Sepiolidae family of bobtail squids.

Atlantic Bobtail

The Atlantic Bobtail (Sepiola atlantica) is a cephalopod in the Sepiolidae family of bobtail squids.