Reef Octopuses: Characteristics, Behavior, Mating

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Caribbean reef octopus

Caribbean reef octopuses (Scientific name: Octopus briareus) are predominately found in tropical waters in the Caribbean Sea, western Atlantic Ocean and Gulf of Mexico, ranging from southern Florida, through the southeast coast of the Gulf of Mexico, the Bahamas, and the Caribbean, to the northern coast of South America. Caribbean reef octopuses are typically found in reefs or other coastal areas. at depths of three to 20 meters (10 to 66 feet) in water temperatures around 20-30°C (68-86°F). The make dens in coral reefs, which they use for protection and are usually dark and exclude other organisms. [Source: Lindsey Lee, Animal Diversity Web (ADW) /=]

The average lifespan of Caribbean reef octopuses in the wild is 10-12 months. Their average lifespan in captivity is 10-17 months. Males die a few months after they give their hectocotylus (sperm box) to the females for reproduction. The females usually die shortly after laying the eggs and ensuring the eggs are well hidden.

Caribbean reef octopuses have not been evaluated for the International Union for Conservation of Nature (IUCN) Red List and have no special status according to the Convention on the International Trade in Endangered Species (CITES). Caribbean reef octopuses are captured by some artisanal fishermen who end up selling them for pet trade. Rarely do they end as food for humans. These octopuses are used in biomedical research of the nervous system,blood-brain barriers, blood pigments, immune mechanisms, neurotransmitters, environmental toxicology, and hormonal control of reproduction and aging.

Websites and Resources: Animal Diversity Web (ADW); National Oceanic and Atmospheric Administration (NOAA); Fishbase ; Encyclopedia of Life ; Smithsonian Oceans Portal

Caribbean Reef Octopus Characteristics

Caribbean reef octopuses on average weigh one kilogram (2.2 pounds) and reach the length of 12 centimeters (4.72 inches), with their average length being 5.4 centimeters (2.13 inches). Sexual Dimorphism (differences between males and females) exists: Males and females have different shapes. They are cold blooded (ectothermic, use heat from the environment and adapt their behavior to regulate body temperature). [Source: Lindsey Lee, Animal Diversity Web (ADW) /=]

Coconut Octopus (Amphioctopus marginatus)

Caribbean reef octopuses are typically bright green and blue with red-brown specks across their bodies. According to Animal Diversity Web: Chromatophores, which are specialized cells in the skin, allow these octopuses to change colors in order to blend in with their background and disguise themselves from predators and prey. These octopuses have sizable, prominent dark red-brown eyes. Their mantles, the body excluding their arms, are an average of 5.4 centimeters long and have been known to grow up to 12 centimeters.

Caribbean reef octopuses have seven rows of teeth. The longest of these octopuses' eight arms, the second and third, grow, on average, five times the length of the mantle. Each arm consists of two rows of suckers, which are connected by loose webs that assist in hunting. In males, the right third arm has a hectocotylus that deposits spermatophores, sacks containing the sperm for mating.

Caribbean Reef Octopus Behavior

Caribbean reef octopuses are nocturnal (active at night), motile (move around as opposed to being stationary), sedentary (remain in the same area), solitary and territorial (defend an area within the home range). They mainly stay around the same reef, and even the same den, for most majority of their lives. At most they change dens a few times over their lifetimes. Caribbean reef octopuses change their dens when they are disturbed by an intruder. They almost always return to their dens after hunting. [Source: Lindsey Lee, Animal Diversity Web (ADW) /=]

Caribbean reef octopuses live alone in dens along coral reefs, only interacting with others for mating purposes. They defend their den, along with the surrounding area, from other octopuses and predators. They have been observed killing other octopuses within their territory and eating them. They like to hunt at night when it is easier to sneak up on prey.

Caribbean reef octopuses have many ways to communicate with other octopuses. These organisms have a sender-receiver match (a species-specific vocalization) that allows them to communicate with each other. Octopuses use a complex skin display, using the chromatophores, to form patterns that other octopuses are able to comprehend. These octopuses also use their layers of iridocytes deep in the dermis of their skin, which produce reflections off the skin, signaling to other octopuses.

Caribbean Reef Octopus Food, Eating Behavior and Predators

Octopus Vulgaris

The primary prey of Caribbean reef octopuses are Caribbean spiny lobsters (Panulirus argus). They also to eat other aquatic crustaceans such as crabs and shrimp, small fish, and small mollusks as well other, particularly smaller, Caribbean reef octopuses. Caribbean reef octopuses use their seven rows of teeth, suckers on their arms, and the web-like structures that connect the tops of their arms together to capture and eat prey. [Source: Lindsey Lee, Animal Diversity Web (ADW) /=]

According to Animal Diversity Web: These octopuses are known to hurdle themselves over reefs, surprising their prey, and capturing them in their web. Then, the octopuses reach underneath, grabbing their prey, and guide it towards their mouths. They also snatch their prey with an arm and roll it up underneath of them, after which they eat the prey. Less frequently, Caribbean reef octopuses have been known to lurk behind their prey and grab it with their front arms. Octopuses' food intake depends on the amount of food available, the water temperature (higher temperatures favor more food eaten), and whether or not the female is pregnant (two weeks before laying the eggs, the female reduces her food intake by 50 percent).

The known predators of octopuses are sharks, large fish, birds, eels, humans, other octopuses (feeding on smaller individuals), and some dolphins and whales. Octopuses have numerous anti-predator adaptations. They have an instinct to flee when they feel threatened, and they are able to squeeze into smaller spaces, giving them an advantage over their bigger predators. Octopuses release ink from a gland which creates a black cloud and allows them to escape under the darkness. Octopuses also are able to change the color of their skin, which is a cryptic adaptation, camouflaging them into their background and hiding them from predators. Lastly, octopuses are known to mimic larger animals by configuring their bodies into different shapes to scare off predators.

Caribbean Reef Octopus Mating, Reproduction and Offspring

Caribbean reef octopuses: 1) engage in internal reproduction in which sperm from the male fertilizes the egg within the female; 2) employ sperm-storing (producing young from sperm that has been stored, allowing it be used for fertilization at some time after mating); and 3) are semelparous. This means that offspring are all produced in a single group, after which the parent usually dies. [Source: Lindsey Lee, Animal Diversity Web (ADW) /=]

Octopuses breed once in their lifetime. Although they breed year-round, spawning peaks around February-March. Most breed between six months to a few years after they reach maturity. The number of offspring ranges up to 200,000. The average gestation period is 65 days. On average males and females reach sexual maturity at age five months.

Octopuses are monogamous, meaning one female and male mate. Caribbean reef octopuses do not have a known mating ritual. Because octopuses are solitary, mates are opportunistically chosen. Sexual reproduction can occur in two different ways for Caribbean reef octopuses. Males can either mount the female, reach its hectocotylus, the sperm containing tentacle, into her oviduct, releasing its sperm to cover the eggs, or take off its hectocotylus and give it to the female so that she can store his arm in her mantle and use it when the eggs are ready to be internally fertilized.

Parental care and pre-fertilization and pre-birth protection are provided by females. Male Caribbean reef octopuses do not have any parental involvement other than providing sperm to fertilize the eggs. The male octopuses are dead by the time the eggs have hatched. The females protect the eggs pre-fertilization by keeping them inside of their body cavities. Once the females lay the eggs in crevices, they do not leave them alone, not even to feed. The female octopuses protect the eggs from predators and keep them clean by pushing water past them. The females usually die before the eggs hatch.

Each egg take approximately 65 days to hatch. Octopuses emerge from their eggs fully independent and weigh 0.095 grams and are 15 millimeters in length with arms of 7-9 millimeters and a mantle averaging 5.5 millimeters. They exit the egg about 15 seconds after they first crack it. These octopuses emerge with the appearance of small adults. Caribbean reef octopuses grow at a rapid rate, increasing their weight by five percent a day. Once octopuses have sexually matured at five months, they will continue to grow. By the time they die they will weigh one-third of the amount of food they have eaten over the course of their life.

Big Blue Octopus

Big blue octopuses (Scientific name: Octopus cyanea) reside in the Indian and Pacific Oceans, scattered in tropical seas from the Hawaiian Islands in the east to the Red Sea and northeast Africa in the west. There have also been reports of them in the Mediterranean Sea and in southeast of Africa such as along the coasts of Madagascar, Tanzania, Somalia, and Seychelles. [Source: Heidi Chicas, Animal Diversity Web (ADW) /=]

Also known as day octopuses, big blue octopuses are typically found in coral reefs and sea grass beds at depths of one to 100 meters (3.28 to 328 feet) at an average depth of around 60 meters (200 feet). They favor reefs or areas with muddy, sandy or rocky bottoms with crevices or coral rubbles beds where they can make lairs or dens. These dens aren't used for a lifetime as is the case with some octopus species. On average individual big blue octopuses spend non more than 35 days in one den.

Octopus cyanea

The average lifespan of big blue octopuses is 12 to 15 months in the wild and in captivity. The longest known lifespan is 18 months. Females die from ovary enlargement after a single spawning around 60 days after laying eggs. There has been a case where a female lived six months longer (24 months total) due to exposure of low temperatures and consequently a lower metabolic rate. Males die from enlargement of specialized suckers, about 13 to 15 months of age.

Big blue octopuses are source of food in some places. In southwest Madagascar big blue octopuses die and are washed up on to shore. They make up 11.8 percent of marine resources with a catch rate of 17,145 kilograms per quare kilometers per year. Big blue octopuses have not been evaluated for the International Union for Conservation of Nature (IUCN) Red List or for Convention on International Trade in Endangered Species (CITES). They may be threatened by coral bleaching and climate change to the coral reef ecosystems where they live.

The main predators of big blue octopuses are monk seals, large fish, moray eels, sperm whales, dolphins and sharks. Their main antipredator adaptation is the ability to camouflage themselves. There are five mechanisms in this category: 1) camouflaging into any background, 2) countershading, 3) mimicry (mimicking a venomous fish like the banded sole), 4) changing their appearance into different things, 5) controlled ability to change their phenotypes (observable characteristics). Big blue octopuses can spot a predator from almost eight meters away. Once spotted, octopuses will either camouflage themselves or hide in their dens. They also can squirt ink. Ink may blind a predator and inhibit it sense of smell, allowing the octopus to escape.

Big Blue Octopus Physical Characteristics

Big blue octopuses are commonly mistaken for the common octopuses (Octopus vulgaris). They both have eight tentacles, a large head, the same reddish brown color, and the ability to camouflage. The big blue octopus gets it name from the dark blue circles across their skin and this is the main visible thing that distinguishes them from common octopuses. Big blue octopuses range in weight from 0.2 to 6.6 kilograms (0.4 to 14.5 pounds), with their average weight being 1.2 kilograms (2.6 pounds). Their average length is 80 centimeters (2.6 feet). The is some sexual dimorphism (differences between males and females): females are larger than males and males and females have slightly different shapes and different anatomical features. [Source: Heidi Chicas, Animal Diversity Web (ADW) /=]

Big blue octopuses are cold blooded (ectothermic, use heat from the environment and adapt their behavior to regulate body temperature) and heterothermic (have a body temperature that fluctuates with the surrounding environment). They generally measure 16 centimeters from head to dorsum, and 80 centimeters from arm to arm. Males have a longer arm (the third right one), reaching to about 48 centimeters (1.6 feet). Males have very large suckers when they are seven to nine months of age. The suckers are usually the 7th or 8th pair of suckers. /=\

Big blue octopuses reach their full sizes between 13 to 15 months, right before reproduction. Males are sexually mature at 0.32 kilograms and females reach maturity at or above 0.6 kilograms. Size variation depends on food availability. Adult females range from 0.6 to 4.8 kilograms grams and males range from 0.4 to 6.6 kilograms. /=\

Big Blue Octopus Behavior, Feeding and Communication

Big blue octopuses are diurnal (active mainly during the daytime), motile (move around as opposed to being stationary), sedentary (remain in the same area) and solitary. They generally stay in a den for 35 days and typically forage within 80 meters of their den. The maximum distance in which they venture from their den that has been observed is 129 meters. They are territorial and will defend their den. Although big blue octopuses are equipped for swimming , they along crawl along the sea floor rather than actively swim. When they swim one of their three hearts — the systemic heart — stops beating. [Source: Heidi Chicas, Animal Diversity Web (ADW) /=]

Big blue octopuses differ from most octopus in that they are daytime hunters. According to to Animal Diversity Web: They spend about 30 percent of the daytime foraging and at night barricade their dens with rocks to avoid predators. They are solitary creatures that only interact with each other for reproduction. They are very aggressive, and larger individuals can cannibalize smaller ones. Specialized pigments in their skin give them the ability to camouflage to their surroundings for hunting and avoiding predation. These octopuses also have the ability to release black ink when threatened. They squirt ink at their predators, which inhibits the predators’ vision and their sense of smell. This helps big blue octopuses to escape without being tracked. /=\

big blue octopus hiding

Big blue octopuses communicate with vision and touch and sense using vision and touch. Most cephalopods can use camouflage in their surroundings and change their color to communicate with other octopuses. This is true to some extent with big blue octopuses. They use specific colors and lighting to communicate with each other. When males are trying to catch the attention of females, they tend to change into dark colors when in an area where there is a lot of light. Their keen eyesight is used for creating foraging paths. They first scan for predators and they visually wait for their prey to get close enough to trap them. Big blue octopuses use tactile senses to morph into surrounding objects. Males also use their tactile senses for mating, locating where to insert the sperm.

Big blue octopuses are also called day octopuses because they hunt diurnally, an uncommon trait among octopuses. On average, octopuses spend 28 to 30 percent of the daytime foraging. They have a very diverse diet and are opportunistic feeders. Their main prey are sessile molluscs, small fish, and crustaceans. Juvenile octopods have similar diets but eat smaller prey.

Big Blue Octopus Mating and Reproduction

Big blue octopuses are oviparous (young are hatched from eggs) and engage in internal reproduction in which sperm from the male parent fertilizes an egg from the female parent. They employ sperm-storing (producing young from sperm that has been stored, allowing it be used for fertilization at some time after mating). Big blue octopuses engage in year-round breeding. Females breed once in their life time The number of offspring ranges from 500,000 to 1,000,000, with the average number of offspring being 700,000. The average gestation period is 60 days. Both males and females reach sexual maturity at 10 to 12 months. [Source: Heidi Chicas, Animal Diversity Web (ADW) /=]

Big blue octopuses are polygynous — males have more than one female as a mate at one time. Females die after spawning because they stop eating to protect their eggs. The timing for reproduction depends on when they reach their sexual maturity. Males make spermatophores. According to Animal Diversity Web: When they grow their third right arm to its full length (43 centimeters) they are able to insert it into females’ mantle cavity and deliver their sperm internally.

Atlantic pygmy octopus

Big blue octopuses usually mate during the day while foraging. Males can spot a female from 8 meters away. Males will wave their longer tentacle to attract females. There have been some cases where females will take males into their dens to mate, but typically they will mate on solid surfaces. Females turn very aggressive during mating season and there have been some cases of sexual cannibalism.

Parental care, pre-fertilization and Pre-birth protection is provided by females. Big blue octopus eggs weigh up to 0.33 grams and are three millimeters in length. Females lay their eggs near the surface of the water. Females stop eating after spawning and die 60 days after laying their eggs, which they protect from predators. Some females brood without the presence of their eggs. They protect their eggs day and night, never taking time out to eat. Approximately 10 days after the last egg hatches, female big blue octopuses die. There have been some cases where they live longer due to lower temperatures which slows down their metabolism and ovary gland enlargement.

Atlantic Pygmy Octopuses

Atlantic pygmy octopuses (Scientific name: Octopus joubini) are one the smallest octopuses. Residing in tropical waters in the tropical Western Atlantic, Gulf of Mexico and the Caribbean Sea, from Florida to the Guyanas, Bahamas and West Indies, they are found in reefs, coastal areas and on or near the sea bottom, inhabiting empty shells among coral, near low tide line and below in shallow water. Also known as Joubin's octopus, they use crevices, empty clam shells, or spaces in a reef face to eat and rest. [Source: Nichole Rudolph, Animal Diversity Web (ADW) /=]

Atlantic pygmy octopuses reach a maximum length (including arms) of approximately 15 centimeters (six inches). They have eight arms. One arm, the ligula, is modified in males to form a sex organ, so it may look like it only has seven arms. This species has smooth skin with small pimples scattered at intervals. Despite their small size,, the Atlantic pygmy octopus grows rapidly during their relatively short life of four to eight months. Their small size seems to be the result of their small size when they hathc from eggs and the short duration of their growth. They have keen senses, especially vision. They are sometimes used in behavioral and biomedical research and have not been evaluated by International Union for Conservation of Nature (IUCN) Red List.

The preferred food of the Atlantic pygmy octopuses is Uca fiddler crabs, but they also consume snails. They perhaps prefer crabs because they come into more contact with them more and the have to spend a long time pulling snails out of their shells. A crab they can kill and eat in less than a minute. Like most octopuses, Atlantic pygmy octopuses are usually solitary animals and prefer the same areas of residence. In tank experiments, they move to the corners of the tank for safety and more "cover." They form hierarchies, with dominance usually based on size. The bigger octopus that routinely win disputes gain access to better food and homes. When there is a large difference in size between two animals, they tend to ignore each other and make their social arrangements using space.

Mating time is usually brief — about five minutes, a short time compared with other species like the giant Pacific octopus, which mates for 2-3 hours. According to Animal Diversity Web The amount of contact and sex of the initiator seems to vary. As a result of its small size, the animal is vulnerable to many predators. A shorter mating time shortens the period of vulnerability to these predators. It can occasionally cause problems, however. The sperm is passed to the female through a spermatophore that the males, using a special arm, place in the female's mantle cavity. The spermatophore evaginates in the female's oviduct, releasing sperm. Usually males would hold the spermatophore in the female until this process is complete, but in this case the male cannot because the fertilization takes too long. The eggs produced are usually fairly large, 6-8 millimeters in length. The females begin spawning from 4-5 months after hatching, with death shortly after 30-45 day brooding period. /=\

Image Sources: Wikimedia Commons, NOAA

Text Sources: Animal Diversity Web (ADW); National Oceanic and Atmospheric Administration (NOAA); Wikipedia, National Geographic, Live Science, BBC, Smithsonian, New York Times, Washington Post, Los Angeles Times, The New Yorker, Reuters, Associated Press, Lonely Planet Guides and various books and other publications.

Last Updated April 2023

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