Marine Wildlife Encyclopedia
Caribbean Reef Octopus Octopus briareus
Species ID: O.OB
Description: A typical octopus, with a large bulbous body atop a series of eight long legs. The dark ring surrounding the eye, and the lack of dark borders on its suckers, help identify the Caribbean reef octopus. This species often appears iridescent blue-green in colour with brown mottling, but can change colour, and even texture, at will. Males can be distinguished from females by the presence of the flat, paddle-like sex organ on the end of one tentacle. Juveniles resemble adults
Maximum Size: 100 cm (40 in), when including the arms
Longevity: 17 months
Status: Not currently on the IUCN endangered species list
Caribbean Reef Octopus & People: This species is not fished commercially, but is caught by fishermen throughout its range for local consumption
Geographical Range: Common throughout south Florida, the Caribbean and the northern coast of South America
Coral Reef Zone: This species is common in shallow waters such as the shore, back reef and reef flat zones, but is also found in the fore reef zone
Favourite Habitat: Octopuses prefer areas with many caves and crevices in which they can hide
Depth Range : 4.5–23 m (15–75 ft)
A Day in The Life
Dawn: Octopus hunting activity declines and they return to the shelter of a cave for the day
Day: Octopuses hide in their shelter but may emerge to mate
Dusk: Octopuses emerge from their shelters and begin hunting
Night: Octopuses are active, scouring the reef for food
Who Eats Who
The octopus is a carnivore, feeding mainly on crustaceans such as crabs, shrimp, lobster, clams, snails, as well as small fish. This species is also known to feed on carrion, and cannibalism is common among these opportunistic hunters. Although octopuses are masters of disguise, they (and their eggs) are regularly consumed by many reef carnivores including grouper, snapper, nurse sharks, and especially eels, which are capable of following the scent of an octopus to its cave.
Scuba Diver & Snorkeler Best Practices
Don’t disturb the wildlife : Interfering with wildlife may frighten them, disrupting feeding and mating behaviours, and even provoking at attack on you. Hanging onto marine wildlife such as turtles, dolphins and whale sharks can cause them stress. Maintain your distance—wildlife will spend longer in your vicinity if they feel comfortable in your presence.
Octopuses remain hidden within caves during the day, but emerge at night and are easily recognized by their blue-green iridescence under divers’ lights. Slow movements should allow a close approach, but if startled the octopus will rapidly retreat.
Caribbean reef octopuses are carnivores, feeding at night, when they either wait to ambush prey or actively search the reef. These octopuses feed using a variety of techniques, the most common of which is to spread out their webbed tentacles like a parachute over a small area to trap prey. Octopuses also camouflage themselves and shoot an arm out to grab unsuspecting prey. Finally, this species has been seen crawling along the reef with two out-stretched arms, which it uses as pincers to grab prey. Occasionally, octopuses eat each other – a practice called cannibalism. One can sometimes see an octopus curled around the blanched carcass of another octopus while it feeds.
Observe, record & share:
O O.OB-101 – Parachute: Octopus pounces over prey with tentacles spread out like a parachute
O O.OB-102 – Grab: Octopus, often camouflaged, flings out an arm to snatch prey
O O.OB-103 – Pincer: Octopus hunts with two out-stretched arms as pincers
O O.OB-104 – Cannibalism: Octopus seen feeding upon the carcass of another octopus
Attack & Defense Behaviour
Caribbean reef octopuses are fiercely territorial. If another octopus trespasses near its den, the resident octopus comes out to confront it. If the intruder does not retreat, the pair will engage in combat which sometimes ends in death by strangulation if the losing octopus cannot escape. If killed, the loser is often eaten by the victor. Octopuses avoid their many reef predators mainly through their excellent camouflage – they can change colour and even texture to blend into almost any habitat. If approached too closely, they will jet away, leaving behind a cloud of black ink to confuse the threat. If cornered in their den or caught by a predator, an octopus will roll into a protective ball by curling all its tentacles back over its head to protect the vital organs.
Observe, record & share:
O O.OB-201 – Camouflage: Look carefully for octopuses blending into the reef
O O.OB-202 – Inking escape: If startled, octopuses jet away while leaving a cloud of ink behind
O O.OB-203 – Protective ball: The octopus curls into a protective ball with the tentacles covering the head
O O.OB-204 – Combat: Two octopuses grapple until one can escape or one strangles and kills the other
Octopuses remain hidden within caves during the day, but emerge at night and are easily recognized by their blue-green iridescence under divers’ lights. Slow movements should allow a close approach, but if startled the octopus will rapidly retreat. Caribbean reef octopuses reproduce sexually and do not undergo sex change during development. Males leave their dens during the day to look for mates. Once they find a female they climb on top of her without any obvious courtship displays and begin mating, which can last up to 80 minutes. While mating, males wrap their tentacles around the female’s head and slide a modified tentacle under her mantle to transfer sperm to her, which the female can store and use for up to several months. This intimate encounter is the beginning of the end for males, which usually die soon after mating. Females live slightly longer. They return to their nest and lay up to 500 eggs, which resemble pale pearly sausages roughly 2 cm (3/4 in) long. The eggs hatch after about 65 days, during which time the female defends the nest fiercely, refusing to leave it even to eat. Once the eggs hatch, the young octopuses leave the cave and begin life on the reef straight away, without passing through a planktonic stage. Mating in this species is thought to occur year round, but peaks from December to March.
Observe, record & share:
O O.OB-301 – Female guarding eggs: Females stay at a cave entrance, even at night, and attack anything that comes too close
O O.OB-302 – Mating: Males sit on top of females and wrap their arms around her while mating
O O.OB-303 – Eggs: Resemble small pearly sausages tethered to the roof of a cave with a thin thread
Speculative hunting: Caribbean reef octopuses are often seen prowling the reef at night and randomly pouncing on rocks and coral heads with their webbed arms spread out like a parachute. This technique is known as “speculative hunting” because the octopus does not necessarily know if there is prey in this area. By attacking in this way, the octopus retains the element of surprise, and can then take its time to feel around for food because nothing can escape from under its body. When one of its probing arms finds prey, it is fed into the mouth under the center of the web.
Did You Know?
• Caribbean reef octopuses often return to the same den after a night of hunting, but can change dens several times over their brief life. When moving into a new den, an octopus will pull rocks and pieces of coral over the entrance to conceal it from potential predators.
• Caribbean reef octopuses, like many other octopus species, are cannibalistic. They often kill and eat intruders into their den, and females that feel harassed by males interested in mating may eat their unlucky suitors.
• These octopuses, like their relatives, live life in fast-forward. Baby octopuses are able to swim, hunt, ink, and change colour as soon as they hatch. Just 17 weeks later they will have reached 3/4 of their adult size, and reach the end of their lifespan roughly a year later.
What to do?
Share your observations today!: Discover your species of interest, observe its behaviour, and share your pictures and videos with friends and coral reef enthusiasts around the world! Upload media to the web, tagged with species common name (ex.: trumpetfish) and species ID code (ex.: A.AM) or species behaviour code (ex.: A.AM-101)