Octopus (Common)

Overview

Octopus vulgaris, the common octopus, is one of the most widely studied and well-known cephalopod species. This medium-sized octopus displays extraordinary intelligence, capable of learning through observation, solving complex puzzles, and using tools. Its soft, muscular body lacks any skeletal structure except for a hard beak, allowing it to squeeze through remarkably small openings. The species is renowned for its sophisticated camouflage system, using specialized skin cells called chromatophores, iridophores, and leucophores to change color and texture in milliseconds. This ability serves both as predator avoidance and hunting strategy. The common octopus possesses three hearts—two branchial hearts that pump blood through the gills, and one systemic heart that circulates blood to the rest of the body. Common octopuses are solitary and territorial, spending daylight hours in dens among rocks or crevices, emerging primarily at night to hunt. They exhibit complex behaviors including play, individual personality traits, and sophisticated hunting techniques. Their intelligence is considered among the highest of all invertebrates, with studies demonstrating short- and long-term memory capabilities. This species plays an important ecological role as both predator and prey in marine ecosystems, and has significant commercial value in Mediterranean, Asian, and Latin American fisheries. Despite heavy fishing pressure in many regions, the species' short generation time and high fecundity have helped maintain populations, though monitoring continues in heavily exploited areas.

How to identify

The common octopus typically reaches 60-90 cm in total length with arms accounting for most of this measurement. The body (mantle) is oval and muscular, usually 8-25 cm long. Coloration is highly variable due to camouflage abilities, but resting color is often brownish-gray or reddish-brown with mottled patterns. Eight arms of roughly equal length bear two rows of suckers (approximately 240 suckers per arm). Skin texture can change from smooth to heavily papillated. The eyes are large and highly developed with W-shaped pupils. No fins are present on the mantle, distinguishing it from squid. Males can be identified by a specialized third right arm (hectocotylus) used in reproduction.

Habitat

Common octopuses inhabit coastal waters from the intertidal zone to depths of approximately 200 meters, though most commonly found between 0-100 meters. They prefer rocky substrates, coral reefs, seagrass beds, and areas with abundant crevices for den construction. Temperature tolerance ranges from 10-30°C, with optimal conditions between 15-25°C. The species requires well-oxygenated water and is found in both clear oceanic waters and more turbid coastal environments. Juveniles may occupy shallower waters than adults.

Distribution

Octopus vulgaris has a cosmopolitan distribution in tropical and temperate seas worldwide. It occurs throughout the Mediterranean Sea, eastern Atlantic from the British Isles to South Africa, western Atlantic from Cape Cod to Argentina (though more common in warmer waters), Indo-Pacific region including the Red Sea, Indian Ocean, and western Pacific. The species is absent from polar and subpolar regions. Recent genetic studies suggest the 'common octopus' may represent a species complex with several cryptic species.

Diet

The common octopus is a carnivorous predator feeding primarily on crustaceans (crabs, lobsters, shrimp), bivalve mollusks (clams, mussels), gastropods, and fish. Hunting occurs mainly at night using chemoreceptors in the suckers to detect prey. The octopus employs various hunting strategies including ambush predation, active pursuit, and extracting mollusks from shells using its beak and radula. It can inject venom through salivary secretions to paralyze prey. Hard-shelled prey is drilled using the radula and salivary papilla. Indigestible parts are discarded in middens outside the den, which can help identify occupied dens.

Behavior

Common octopuses are solitary, territorial, and primarily nocturnal. They establish dens in rock crevices, which they may modify by moving rocks and shells. Advanced camouflage is used for both concealment from predators and prey ambush. When threatened, they can release dark ink to confuse predators while escaping via jet propulsion (expelling water through the siphon). They exhibit remarkable problem-solving abilities, including opening jars, navigating mazes, and using coconut shells or other objects as portable shelters. Individual personality differences have been documented. They show exploratory behavior and can recognize individual humans in captivity.

Reproduction & life cycle

Common octopuses are semelparous, reproducing once before death. Sexual maturity is reached at 12-18 months. Mating involves the male using his hectocotylized arm to transfer spermatophores into the female's mantle cavity. Females lay 100,000-500,000 eggs in strings attached to the roof of their den. The female guards and tends the eggs for 1-4 months depending on water temperature, continuously cleaning them and providing oxygenated water flow. During this brooding period, females typically do not eat. After eggs hatch, releasing planktonic paralarvae, the female dies. Males also die shortly after mating. The planktonic stage lasts several weeks before juveniles settle to the bottom.

When to look

Common octopuses can be observed year-round in most of their range. Reproduction peaks vary regionally but often occur in spring and autumn in temperate waters. In Mediterranean waters, spawning typically peaks in spring (April-May) and autumn (September-October). Juveniles are more abundant in late summer and autumn following spring spawning events. Availability in fisheries may vary seasonally with local regulations and spawning closures.

Cultural significance

The common octopus has significant cultural and culinary importance throughout the Mediterranean, East Asia, and Latin America. It is a staple in Greek, Italian, Spanish, Portuguese, Japanese, and Korean cuisines, prepared through various methods including grilling, stewing, and pickling. In ancient Mediterranean cultures, octopuses appeared in art and mythology, including Minoan frescoes. The species has become important in neuroscience and cognition research due to its intelligence and unique nervous system. Octopus symbolism varies culturally from representing adaptability and intelligence to mystery and the unknown. The species is commonly displayed in public aquariums worldwide due to its charisma and behavioral complexity.

Similar species

• Octopus insularis (Caribbean reef octopus)
• Octopus tetricus (gloomy octopus)
• Octopus cyanea (big blue octopus)

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