The Caribbean reef octopus, with its iridescent blue and green skin, is easy for divers to spot at night time. However, prey aren’t so lucky– this octopus is a master of the nocturnal ambush.
This species can be a fearsome foe for small reef critters! It flares out its arms and webbing like a huge net, engulfing entire heads of coral and trapping the creatures in its “net.”
It only takes 15 seconds for this octopus’s babies to fully hatch from their eggs!
This species is a moderately-sized with a mantle length to 120 mm and a total length 60 cm ( 2 ft). It often weighs around 1 kg (2 lbs) though there are reports of possible longer specimens weighing up to 1.5 kg (3 lbs). The arms are 4-6x the mantle length and there are two rows of large suckers on each arm.
Like many octopuses, this species grows fast and has a short life span of just 10 to 12 months. Mother octopus lays 200-500 large eggs between 1-1.4 cm (0.5 inch) in length, arranged in clusters. The male dies in the month following fertilization. The eggs develop within 50-80 days into miniature adults ready for a benthic lifestyle as soon as they hatch! These mini caribbean reef octopus have a mantle length of 5.5 mm (0.2 in) and are ready to change color, use jet propulsion, crawl, and squirt ink!
They grow at a rapid rate, on average increasing their weight by 5% per day. Within 17 weeks they are able to reach around 75% of their adult size, males are sexually mature within 140 days and females within 150 days.
The species is found along the western Atlantic ocean including South Florida, Bahamas, southeastern Gulf of Mexico, Caribbean Sea to northern South America including the West Indies and off the coast Curaçao.
This is a shallow-water species typically associated with coral reefs with a depth range from 3 to 20 m (9-65 ft). It can also be found in seagrass, rubble and sandy bottom habitats. They tend to inhabit rocky or structured dens during the daytime making them very difficult to find.
Adults eat shrimps, bivalves, crabs, probably gastropods, the Caribbean spiny lobster (Panulirus argus) and occasionally polychaetes (worms).
Octopus briareus doesn’t overeat…must be nice! This octopus does not regulate its food intake, but has its food intake largely under control of two environmental factors: water temperature and prey abundance. In a study, octopuses doubled their food intake from 20C to 30C (68F-85F) water temperature and octopuses ate more crabs when offered. More crab? Yes, please!
The Caribbean reef octopus has large prominent eyes and is one of the few octopuses that has a blue-green iridescent appearance when its chromatophores are retracted. This species has irregular red-brown mottling, which gives it a marbled pattern on its mantle and arm webbing. It also has regular red-brown transverse bands along the arms in some color patterns and it can be covered with small, round papillae.
The Caribbean reef octopus is a nocturnal species foraging at night amongst live coral and coral rubble. Its web is large, deep, and thin allowing it to envelope small coral heads within the ballooning web. This foraging behavior is known as the parachute attack.
For capturing spiny lobster, the octopus attacks by grasping the lobster’s carapace or long antennae. Ever heard the sound (aka stridulation) produced by a spiny lobster? This sound is produced by a specialized organ located at the base of the long 2nd antennae. This is a defense tactic (along with tailflip and spiny antennae) against predators like the Caribbean reef octopus!
Messenger, J.B. (1963) Behavior of Young Octopus briareus Robson. Nature 197:1186-1187. DOI: 10.1038/1971186a0
Borer, K. (1971) Control of food intake in Octopus briareus Robson. Journal of Comparative and Physiological Psychology. 75:171-185. ISSN: 0021-9940
Bouwma, P.E. and Herrnkind, W.F. (2009) Sound production in Caribbean spiny lobster Panulirus argus and its role in escape during predatory attack by Octopus briareus. New Zealand Journal of Marine and Freshwater Research 43:3-13.
Raising and Rearing Octopus briareus by Dr. James B. Wood, The Cephalopod Page (TCP), thecephalopodpage.org/rearing.php
Mohammed, Karen, 2015. Octopus briareus (Caribbean Reef Octopus), The Online Guide to the Animals of Trinidad and Tobago
Caribbean Reef Octopuses, Octopus briareus, The MarineBio Conservation Society – marinebio.org/species/caribbean-reef-octopuses/octopus-briareus
Jereb, P.; Roper, C.F.E.; Norman, M.D.; Julian K Finn (eds), Cephalopods of the world. An annotated and illustrated catalogue of cephalopod species known to date. Volume 3. Octopods and Vampire Squids. FAO Species Catalogue for Fishery Purposes. No. 4, Vol. 3. Rome, FAO. 2014. 370 p. 11 colour plates.
Lee, L. 2017. “Octopus briareus“, Animal Diversity Web.
Allcock, L. & Headlam, J. 2018. Octopus briareus. The IUCN Red List of Threatened Species 2018: e.T163175A980439. https://dx.doi.org/10.2305/IUCN.UK.2018-2.RLTS.T163175A980439.en
Caribbean Reef Octopus, Octopus briareus, CEPHALOPODS, CRUSTACEANS, & OTHER SHELLFISH, Oceana oceana.org/marine-life/cephalopods-crustaceans-other-shellfish/caribbean-reef-octopus
Octopus briareus Robson, 1929, Caribbean reef octopus, Palomares, M.L.D. and D. Pauly. Editors. 2019. SeaLifeBase, sealifebase.ca/summary/Octopus-briareus.html
Argonaut octopuses are best known for what appears to be a beautiful, delicate spiral shell. We now know that female argonauts spend their whole lives growing these thin ‘shells’, which they use as buoyant submersibles and as brood chambers for their eggs. But what about male Argonauts? For hundreds of years, no one ever saw