Octopus bimaculatus

Last updated

Verrill's two-spot octopus
Verrill's Two-spot Octopus imported from iNaturalist photo 111685364 on 18 November 2023.jpg
Cayucos, California, 2021
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Mollusca
Class: Cephalopoda
Order: Octopoda
Family: Octopodidae
Genus: Octopus
Species:
O. bimaculatus
Binomial name
Octopus bimaculatus
Verrill, 1883

Octopus bimaculatus, commonly referred to as Verrill's two-spot octopus, is a similar species to the California two-spot octopus (Octopus bimaculoides), which it is often mistaken for. The two can be distinguished by the difference in the blue and black chain-like pattern of the ocelli. O. bimaculatus hunt and feed on a diverse number of benthic organisms that also reside off the coast of Southern California. Once the octopus reaches sexual maturity, it shortly dies after mating, which is approximately 12–18 months after hatching. Embryonic development tends to be rapid due to this short lifespan of these organisms.

Contents

Description

Octopus bimaculatus is typically light brown and spotted in color with a distinctive blue and black false eye, or ocellus, under each eye. The mantle, including the beak and mouth, is located at the center of eight arms. Each of the arms is lined with suckers that are used to help with grasping prey, rocks, and forming shelters.

Similar to other octopus species, O. bimaculatus has skin covered in chromatophores. [2] During the post-larval stage, there are only a few chromatophores and they are called the "founder chromatophores". However, as the octopus matures, more chromatophores form and cover the skin. These chromatophores are pigments that the octopus can expand to create large disc of color that can blend in with the surrounding environment. This is an important behavior that can be used in both defense against predators or to remain hidden from prey before an ambush attack. [3]

Fully mature octopus grow to be about 47 centimeters (18 inches) long. [2]

Distinctive features

O. bimaculatus gets its name "two-spotted octopus" from the blue and black ocelli under each eye. One potential function of these bright blue ocelli is to allow the octopus to appear as a different animal with large eyes as it swims swiftly through the water. [4]

O. bimaculatus is often confused with the California two-spot octopus (Octopus bimaculoides) as both species have two distinctive black and blue ocelli beneath the eyes and above the arms. There are a few key features for telling the two species apart. The blue ring of the ocelli for O. bimaculatus does not have the same distinctive chain-like pattern that O. bimaculoides has. For O. bimaculatus the pattern is still chain-like but more irregular, asymmetrical, and disproportionate, while for O. bimaculoides, the chain-like pattern is more symmetrical and orderly. [5]

The two species also lay eggs of sizes. O. bimaculatus eggs are much smaller and hatch into planktonic larvae, while O. bimaculoides lays larger eggs that produce benthic young. Additionally, O. bimaculatus is generally the larger of the two species. [5]

Difference in chain-like pattern of ocelli between O. bimaculatus and O. bimaculoides O. bimaculatus vs. O. bimaculoides.jpg
Difference in chain-like pattern of ocelli between O. bimaculatus and O. bimaculoides

Feeding

Diet

O. bimaculatus is known to prey on crustaceans, snails, chitons, limpets, and bivalves. Studies have observed the predator-prey interactions between the O. bimaculatus and the Californian scorpionfish (Scorpaena guttata) in aquariums. Findings suggest that the Californian scorpionfish is included in the diet of O. bimaculatus in their natural habitat, specifically juvenile scorpionfish. [6] As juveniles, the octopus tend to prey on smaller benthic, marine invertebrates which include chitons, bivalves, snails, and crabs. [7] Additionally, diet appears to be strongly influenced by location, season, and sex. [8] [9]

Hunting

O. bimaculatus hunt regularly by swimming along the seafloor and pouncing at their prey using their web to feel if they successfully captured their prey. After capture, they use their beak and radula to consume their prey. There has been observations of certain species of fish following the octopus into kelp forests looking for scraps from the octopus prey. [4]

Distribution, habitat, and behavior

O. bimaculatus occurs in the northeast Pacific off the coast of Southern California (north to Point Conception) and Baja California (the exact southern limit is unknown) [1] mainly in the intertidal and subtidal regions. These octopus have been observed in kelp forests, bed rock, and rock walls. Typically found on the seafloor, these octopus occupy areas beneath rocks, inside of holes and inside crevices. Juvenile octopus utilize the smaller areas in bedrock, including empty shells found around the bedrock. They frequently use shells for shelter, including the shells of Cypraea spadicea, Astraea undosa, and Hinnites giganteus. [10]

Larger octopus have the ability and power to "blow" sand or move sand to create shelter. They do this through a mechanism called jet propulsion, which allow them to pump water out quickly through a siphon exerting enough force to move sediment. This process allows the octopus to dig deep holes for shelter in a matter of minutes. The arms of O. bimaculatus are also useful in creating shelter. Each arm is covered in suckers that give the octopus the ability to grip and move smooth wet surfaces such as rocks and shells. [11]

Octopus tend to move from shelter to shelter only residing in one shelter for a short 1–3 month time period before moving on to the next. [10] Octopus leave their shelters for a number of reasons, the primary reason being to forage. Other reasons include competition for space with other octopus or fleeing an area with high risk of predation.

Predators known to hunt O. bimaculatus include the California sheephead (Semicossyphus pulcher), the kelp bass (Paralabrax clathratus), and the California moray eel (Gymnothorax mordax). [12]

Life history

Lifespan

O. bimaculatus lives about 12–18 months. Young are planktonic for one to several months before settling on the ground. However, in captivity, O. bimaculatus has been observed to live up to 2 years. [2]

Reproduction

Most matings occur in May and June when water temperatures are rising, and females then lay their eggs between April and August, though they can mate throughout the year.

Mating usually takes between 10 and 60 minutes. During this time, the male extends a modified arm called the hectocotylus, which transfers spermatophores to the female. [13] [14] After the eggs are fertilized, the females lay their eggs in a sheltered area protected by rocks.

The amount of eggs laid depends on the size on the female, but typically the number of eggs are very high, with the average being approximately 20,000 eggs, about 100 to 250 per strand. The larger females tend to lay more eggs than the smaller females. After the eggs are laid, the females stay to care for and protect the eggs until they hatch into planktonic larvae. [15] Females tend to die during the process of watching over the eggs due to starvation and exhaustion. [2]

Development

The stages of development on average range over a period of 50.4 days after fertilization occurs. [15] The eggs take 30 to 90 days to fully develop, depending on water temperature. Studies have found development time is shortest when the water temperature is at 19.7 C.

There are two major stages in the development; the rapid initial stage and the second slower stage. [2] Newly hatched eggs are planktonic and on average are 4 mm long from the top of the mantle to the end of the arms. Much of the embryonic development is similar to that of the common octopus (Octopus vulgaris). [15]

Related Research Articles

<span class="mw-page-title-main">Cephalopod</span> Class of mollusks

A cephalopod is any member of the molluscan class Cephalopoda such as a squid, octopus, cuttlefish, or nautilus. These exclusively marine animals are characterized by bilateral body symmetry, a prominent head, and a set of arms or tentacles modified from the primitive molluscan foot. Fishers sometimes call cephalopods "inkfish", referring to their common ability to squirt ink. The study of cephalopods is a branch of malacology known as teuthology.

<span class="mw-page-title-main">California two-spot octopus</span> Species of cephalopod

The California two-spot octopus, often simply called a "bimac", is an octopus species native to many parts of the Pacific Ocean including the coast of California. One can identify the species by the circular blue eyespots on each side of its head. Bimacs usually live to be about two years old. They are closely related to Verrill's two-spot octopus. In 2015, O. bimaculoides became the first octopus to have a fully sequenced genome.

<span class="mw-page-title-main">Greater blue-ringed octopus</span> Species of venomous cephalopod

The greater blue-ringed octopus is one of four species of extremely venomous blue-ringed octopuses belonging to the family Octopodidae. This particular species of blue-ringed octopus is known as one of the most toxic marine animals in the world.

<span class="mw-page-title-main">California sheephead</span> Species of fish

The California sheephead is a species of wrasse native to the eastern Pacific Ocean. Its range is from Monterey Bay, California, to the Gulf of California, Mexico. It can live for up to 20 years in favorable conditions and can reach a size of up to 91 cm (3 ft) and a weight of 16 kg (35 lb). It is carnivorous, living in rocky reef and kelp bed habitats, feeding primarily on sea urchins, molluscs, and crustaceans.

<span class="mw-page-title-main">Giant Pacific octopus</span> Species of cephalopod

The giant Pacific octopus, also known as the North Pacific giant octopus, is a large marine cephalopod belonging to the genus Enteroctopus and Enteroctopodidae family. Its spatial distribution encompasses much of the coastal North Pacific, from the Mexican state of Baja California, north along the United States' West Coast, and British Columbia, Canada; across the northern Pacific to the Russian Far East, south to the East China Sea, the Yellow Sea, the Sea of Japan, Japan's Pacific east coast, and around the Korean Peninsula. It can be found from the intertidal zone down to 2,000 m (6,600 ft), and is best-adapted to colder, oxygen- and nutrient-rich waters. It is the largest octopus species on earth and can often be found in aquariums and research facilities in addition to the ocean. E. dofleini play an important role in maintaining the health and biodiversity of deep sea ecosystems, cognitive research, and the fishing industry.

<span class="mw-page-title-main">Atlantic pygmy octopus</span> Species of cephalopod

The Atlantic pygmy octopus, also known as the small-egg Caribbean pygmy octopus, is a small species of octopus in the order Octopoda. Fully grown, this cephalopod reaches a mantle length of 4.5 cm with arms up to 9 cm long. They are known for being intelligent creatures with keen senses, particularly good sight.

<span class="mw-page-title-main">East Pacific red octopus</span> Species of cephalopod

Octopus rubescens is the most commonly occurring shallow-water octopus on much of the North American West Coast and a ubiquitous benthic predator in these habitats. Its range extends from the southern Gulf of California to at least the Gulf of Alaska, but may also occur in the western Pacific Ocean. O. rubescens occurs intertidally to a depth of 300 m (980 ft).

Euprymna hyllebergi, the Thai bobtail squid is a species of squid belonging to the family Sepiolidae and is native to the eastern Indian Ocean. It is commonly found in the Andaman Sea of Thailand and in the Gulf of Thailand. E. hyllebergi can grow up to 35mm in mantle length and can be found in depths as low as 74m. The Thai bobtail squid is covered in chromatophores, which are pigmented cells that can expand or contract and are used to camouflage the squid. The normal lifespan of the Thai bobtail squid is between 92 and 122 days for males and between 80 and 113 days for females.

<span class="mw-page-title-main">Caribbean reef octopus</span> Species of cephalopod

The Caribbean reef octopus is a coral reef marine animal. It has eight long arms that vary in length and diameter. In comparison to the arms, the mantle is large and bulky. This species is difficult to describe because it changes color and texture to blend into its surroundings, using specialised skin cells known as chromatophores. Its color range is very large; it can change from crimson to green, and bumpy to smooth. It weighs around 3.3 lb or 1.5 kg.

<i>Macroctopus</i> Species of mollusc

Macroctopus maorum is known more commonly as the Maori octopus or the New Zealand octopus. It is found in the waters around New Zealand and southern Australia. M. maorum is one of the largest and most aggressive octopus species living in the New Zealand and Australian waters. They feed mainly on crustaceans and fish. Although they have a short life span, the females lay thousands of eggs and are very protective of them.

<i>Norrisia norrisii</i> Species of gastropod

The marine snail Norrisia norrisii is a medium-sized gastropod mollusk within the family Tegulidae. It has several common names, including Norris's top snail, Norris's topsnail, norrissnail, smooth brown turban snail, or kelp snail. It was first described by G.B. Sowerby I under the name Trochiscus norrisii. It is the only species in the genus Norrisia.

<i>Stichaster australis</i> Species of starfish

Stichaster australis, the reef starfish, is a species of starfish found in the shallow waters of the rocky intertidal of New Zealand. Typically, the animal is endemic to the west coast shores of the North and South Islands, where wave action is increased. They do not usually inhabit ecosystems that have reduced wave action and calm conditions as they prefer a higher-energy environment. These marine invertebrates range in color from pink to purple, but can also be orange. They typically have eleven arms, but sometimes they may have either ten or twelve. As full-grown adults, they are 8 to 10 cm in diameter.

<i>Scorpaena guttata</i> Species of fish

Scorpaena guttata is a species of fish in the scorpionfish family known by the common name California scorpionfish. It is native to the eastern Pacific Ocean, where it can be found along the coast of California and Baja California. Its distribution extends from around Santa Cruz, California, to Punta Abreojos in Baja California Sur, and out to Guadalupe Island. It is also found in the Gulf of California. Another common name is spotted scorpionfish.

<i>Octopus tetricus</i> Species of mollusc

Octopus tetricus, the gloomy octopus, the common Sydney octopus, or the peachy octopus, is a species of octopus from the subtropical waters of eastern Australia and northern New Zealand. O.tetricus belongs to the Octopus vulgaris species group. All species within the O. vulgaris group are similar in morphology, behaviour, and physiology. The English translation of O. tetricus (Latin) is 'the gloomy octopus'. It is a significant species in the fishing industry in Australia. They play an important role in energy flux between trophic levels in the marine environment.

<i>Octopus salutii</i> Species of octopus

Octopus salutii or the spider octopus is a species of cephalopods in the family Octopodidae. It ranges from 4.0 to 13.0 cm ML in males and 3.5 to 16.5 cm ML in females. Octopus salutii are found at depths ranging from 100 to 700m however, they are most abundant at depths of 250 to 500m.

<i>Pinnoctopus cordiformis</i> Species of mollusc

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<i>Wunderpus photogenicus</i> Species of cephalopod

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<i>Bathypolypus sponsalis</i> Species of mollusc

Bathypolypus sponsalis, commonly called the globose octopus, is a deep sea cephalopod that can be found in both the eastern Atlantic Ocean and the Mediterranean Sea. It possesses many morphological traits adapted to a deep sea environment, including large eggs, reduced gills, no ink sac, and subgelatinous tissues. A distinguishing factor are the relatively large reproductive organs. Their diet consists of predominantly crustaceans and molluscs, but they sometimes consume fish as well. Bathypolypus sponsalis usually dies quickly after reproduction and only spawns once in their lifetime. Sexually mature females have a mantle length of at least 34 mm and sexually mature males have a mantle length of about 24 mm. Juveniles are white and transition to dark brown then to dark purple once maturity is reached.

Octopus bocki is a species of octopus, which has been located near south Pacific islands such as Fiji, the Philippines, and Moorea and can be found hiding in coral rubble. They can also be referred to as the Bock's pygmy octopus. They are nocturnal and use camouflage as their primary defense against predators as well as to ambush their prey. Their typical prey are crustaceans, crabs, shrimp, and small fish and they can grow to be up to 10cm in size.

<i>Octopus hubbsorum</i> Species of Octopus

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References

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