Octopus

Identification features

An octopus has a soft sack-like mantle, eight arms lined with suckers, and no internal shell (unlike cuttlefish or squid with different body plans). Eyes are large and human-like; colour and texture can change in seconds.

Common octopus (Octopus vulgaris) in the Mediterranean and adjacent Atlantic often shows mottled browns and hides in dens with shell middens nearby. Tropical reefs host many species with different patterns—blue-ringed octopuses are small and highly venomous in parts of the Indo-Pacific.

Distinguish from cuttlefish (broad fin around the mantle, W-shaped pupils) and squid (more torpedo-shaped, often mid-water). Count arms and watch for a jet siphon beneath the mantle.

• Eight suckered arms
• Soft mantle without external shell
• Rapid camouflage changes
• Dens often marked by shell debris

Habitat and behaviour

Rocky reefs, walls, seagrass edges and rubble from a few metres to recreational limits. Nocturnal activity is common; daytime sightings often involve animals in dens or slowly foraging.

They use jet propulsion to escape and may ink when startled. Touching or prying them from dens causes stress and can injure the animal.

Where and when

Mediterranean favourites include the Medes Islands, Mallorca and Malta/Gozo rocky sites. Red Sea reefs also hold octopus species. Night dives improve odds.

Cooler months can concentrate some Mediterranean activity; tropical sightings are possible year-round on healthy reefs.

Dive tips

Move slowly, keep light levels steady, and never pull an octopus from a hole. Photograph without crowding the den entrance.

Compare your photos in Scuba Steve’s fish identification app—cephalopod lookalikes are a frequent source of confusion.

Frequently asked questions