cuttlefishes

Cuttlefishes are marine mollusks in the class Cephalopoda, order Sepiida, and family Sepiidae. They comprise more than a hundred species, with the genus Sepia containing many well-known forms, such as Sepia officinalis, the common cuttlefish. They are found in coastal and continental shelf waters worldwide, from temperate to tropical seas, often on sandy or seagrass bottoms.

They have a broad, somewhat flattened mantle, eight arms and two longer feeding tentacles. A distinctive internal shell, the cuttlebone, lies within the mantle and provides buoyancy. The skin features chromatophores, iridophores, and leucophores enabling rapid color, pattern, and texture changes for camouflage and signaling.

Cuttlefish possess highly developed eyes and are known for sophisticated vision. Their nervous systems are large for invertebrates, and they show complex behaviors, including learning and problem-solving.

Locomotion involves undulating fins along the mantle for precise maneuvering and jet propulsion by expelling water through the siphon. They feed mainly on crustaceans and small fish, using their two feeding tentacles to strike prey, then consuming it with a sharp beak and radula.

Reproduction is annual for many species. Males transfer spermatophores to females via a specialized arm (the hectocotylus). Eggs are laid on substrates and cared for until hatching; most species die after breeding, giving cuttlefish a short adult lifespan of about one to two years.

Humans consume cuttlefish as seafood, and the cuttlebone is used as a calcium supplement for birds and as an aquarium aid. Some species face pressures from fishing and habitat loss, but the conservation status varies by species and region.