Sealife guideInk, arms and brains: the fascinating world of cephalopodsThe marine mollusks

Last updated on 10/16/2025 at 11:50 PM

The class of cephalopods, derived from the Greek képhalé meaning head and podos meaning foot, includes some of the most astonishing marine animals. Their name perfectly illustrates their anatomy: their foot has evolved into tentacles that surround the head directly. These tentacles, with or without suckers, are used to catch prey, move around, communicate and explore their surroundings.

The common octopus uses camouflage to blend into its surroundings

The stars of the deep

Cephalopods are among the most highly evolved mollusks. The best-known species are the octopus, the squid and the cuttlefish. Each has fascinating characteristics:

The octopus is a master of camouflage, able to change color and texture in an instant.
The squid is a fast swimmer, often living in open waters.
The cuttlefish, with its internal shell called a cuttlebone, can float or dive thanks to precise control of its buoyancy.

The geniuses of the sea

Unlike many other invertebrates, cephalopods have a complex brain and a highly developed nervous system. This gives them real learning and memory abilities.

They can solve problems, recognize shapes, manipulate objects such as opening jars and even escape from aquariums ! The common octopus, for example, learns by observing and can adapt its behavior to different situations.

A natural jet propulsion system

To move around, cephalopods have developed an ingenious form of locomotion: jet propulsion. By expelling water contained in their mantle cavity through a siphon located between the head and the body, they propel themselves quickly in the opposite direction, much like a tiny underwater jet. This technique allows them to flee predators or move gracefully in all directions.

Masters of camouflage and deception

The common octopus can blend into its surroundings by instantly changing the color, brightness and even texture of its skin, thanks to specialized cells called chromatophores. This ability allows it to hunt discreetly or disappear from sight when threatened.

And in the face of immediate danger, cephalopods have another formidable weapon: they release a cloud of black ink that confuses the predator, creating a smoke screen that allows them to vanish into the depths.

Marvels of adaptation

Cephalopods perfectly illustrate the richness and creativity of marine life. Agile predators, clever thinkers and masters of disguise, they continue to fascinate both scientists and the general public.

Studying these creatures means diving into a world where intelligence, evolution and beauty come together in the heart of the oceans.

Discover marine cephalopods

Chambered nautilus
(Nautilus pompilius)

Coconut octopus
(Amphioctopus marginatus)

Common octopus
(Octopus vulgaris)

Curled octopus
(Eledone cirrhosa)

Flamboyant cuttlefish
(Metasepia pfefferi)

Mimic octopus
(Thaumoctopus mimicus)

North Pacific giant octopus
(Enteroctopus dofleini)

Stubby squid
(Rossia pacifica)

Discover marine mollusks

Abe's polycera nudibranch
(Polycera abei)

Adorned stiliger
(Stiliger ornatus)

Hooded nudibranch
(Melibe leonina)

Leech sea slug
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Little leaf sheep
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Nudibranch Trapania palmula
(Trapania palmula)

Spiny pink scallop
(Chlamys hastata)

Zephyr doris
(Hypselodoris zephyra)

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