| Umbrella octopuses | |
|---|---|
 | |
| Opisthoteuthis californiana | |
Scientific classification  | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Mollusca |
| Class: | Cephalopoda |
| Order: | Octopoda |
| Suborder: | Cirrina |
| Family: | Opisthoteuthidae Verrill, 1896 |
| Genera | |
Umbrella octopuses (family Opisthoteuthidae) are a group of pelagic octopuses. Umbrella octopuses are characterized by a web of skin between the arms, causing them to somewhat resemble an opened umbrella when the arms are spread.
Opisthoteuthidae are a group of octopuses characterized by a web of skin in between their arms. They broad U-shaped shell that support muscles for a pair of small fins on the mantle, these fins are far less developed than other families in Cirrina and essentially only act as stabilizers when the animal swims (using a medusoid motion of the arms and webbing). [1] This structure makes the umbrella octopus resemble an umbrella when they spread their arms/web out. The structure of the umbrella octopus has the oral surface below the mantle of the octopuses and the web with their arms surround the bottom of the mantle. [2] Their outer skin has a very delicate consistency that results in white spots appearing on their skin when damaged. [2] Although Opisthoteuthidae are categorized as cirrates, unlike the other cirrates, they do not have an intermediate web; rather, they use the web in between their arms to mimic the intermediate web that other cirrates have. [2] Lacking an intermediate web is what causes the indentations in the outer edge of their arms that make them look like an umbrella.
Opisthoteuthidae lack an intermediate web but they mimic the defensive mechanism of ballooning by extending the web between their arms as much as possible and curving the outer edges of their arms inwards in order to have the edges touch the ground. They also extend their fins parallel to the floor to help keep their balance or they curve them around their mantle. Opisthoteuthidae have been observed to hold this position for five and a half minutes. Another defensive mechanism that Opisthoteuthidae have been observed using is web-inversion which is when they have their arms turned upwards and their web with the oral surface facing outwards. The oral surface can be facing the floor, or the octopuses may lie laterally so their side is in contact with the floor. It has been noted that these defensive behaviors are the positions the octopuses may go into while feeding as well, but it is possible that this could be because of the stress of being captured and placed in an aquarium to be observed. [2]
When resting at the floor, the octopus's behavior falls into one of two tactics: bottom-resting or flat-spreading. Bottom-resting is when the octopus is resting near the floor. It will erect its mantle, curve the outer edges of its arms inwards to have them be the only part making contact with the floor. The fins are extended out parallel to the bottom to maintain balance. When flat-spreading they spread their arms and web, so it is parallel to the bottom and they keep the edges of their arms curved inwards. Their heads will point backwards at a small angle and their fins will be used for stabilization.
Opisthoteuthidae are deep sea creatures that have been found in the Clipperton-Clarion Fracture Zone in the Pacific Ocean at a depth of about 4,800 m. [3] They have also been found in the South China Sea. [4] They stay within 3,000-4,000 meters below sea level and try to stay hovering over the ocean floor.
Family Opisthoteuthidae has classically contained a single genus, Opisthoteuthis, which has recently been split into three genera on the basis of differences in enlarged suckers on male specimens. [5] [6] Genera Grimpoteuthis , Luteuthis , and Cryptoteuthis now are included in the family Grimpoteuthidae.
Cirroteuthidae is a family of pelagic cirrate octopuses comprising at least three species in two genera.
Grimpoteuthis is a genus of pelagic cirrate (finned) octopods known as the dumbo octopuses. The name "dumbo" originates from their resemblance to the title character of Disney's 1941 film Dumbo, having two prominent ear-like fins which extend from the mantle above each eye. There are 17 species recognized in the genus.
Opisthoteuthis californiana, also known as the flapjack octopus, or flapjack devilfish is a species of umbrella octopus.
Cirrina or Cirrata is a suborder and one of the two main divisions of octopuses. Cirrate octopuses have a small, internal shell and two fins on their head, while their sister suborder Incirrina has neither. The fins of cirrate octopods are associated with a unique cartilage-like shell in a shell sac. In cross-section, the fins have distinct proximal and distal regions, both of which are covered by a thin surface sheath of muscle.
Stauroteuthis syrtensis, also known as the glowing sucker octopus or bioluminescent octopus, is a species of small pelagic octopus found at great depths in the north Atlantic Ocean. It is one of a very small number of octopuses to exhibit bioluminescence.
Cirroteuthis muelleri, also known as the big-finned jellyhead, was the first cirrate octopus species to be scientifically described. It is closely related to the genus Cirrothauma within the family Cirroteuthidae. At present the genus contains a single recognized species restricted to the Arctic Ocean and northern basins of the Atlantic and Pacific, but other species may be present in the southern hemisphere.
Cirrate octopuses possess a well-developed internal shell that supports their muscular swimming fins. This is in contrast to the more familiar, finless, incirrate octopuses, in which the shell remnant is either present as a pair of stylets or absent altogether.
Cryptoteuthis brevibracchiata, the short-arm flapjack octopod, is a deepwater species of octopod. It is the only species in the monotypic genus Cryptoteuthis one of the cirrate octopuses of the family Grimpoteuthidae, the umbrella octopuses. It is known from a single specimen which was collected in the northeastern Atlantic Ocean. It has characteristics which are shared with two other genera, Opisthoteuthis and Grimpoteuthis, but is sufficiently distinctive from either of these to warrant the erection of a new genus.
Opisthoteuthis chathamensis, commonly known as the roughy umbrella octopus, is a species of cirrate octopus restricted to demersal habitats surrounding the Chatham Rise in New Zealand.
Opisthoteuthis calypso or calypso flapjack octopus is a species of genus Opisthoteuthis, which are known as the cirrate octopuses. Octopuses in this genus are known as the flapjack octopuses and can be found in a variety of oceans across the world.
Opisthoteuthis agassizii is a lesser-known, deep-sea octopus first described in 1883 by Addison E. Verrill.
Opisthoteuthis borealis is a lesser-known species of octopus found near Greenland and Iceland, especially in the Davis Strait. The species was described from 9 specimens, and is one of the most recent Opisthoteuthis species described. Not much is known about it besides its anatomy and habitat.
Opisthoteuthis bruuni is a species of finned cirrate octopus found along the western coast of South America. Their tissue is almost jelly-like, and they have short, round bodies.
Opisthoteuthis grimaldii is an octopus found near the Azores.
Opisthoteuthis hardyi is a lesser-known octopus species. It was described in 2002 from a male caught off the Shag Rocks, which are far south in the Atlantic Ocean near the Falkland Islands.
Opisthoteuthis persephone is a cirrate octopus living south of Australia. In particular, it lives in waters off Tasmania, Victoria, New South Wales, and South Australia. The octopus has been found 270–540 m (885.8–1,771.7 ft) deep. It lives near and directly above the seafloor. S. Stillman Berry was the first to scientifically describe this species after capturing eight specimens while aboard the F.I.S. Endeavour in the early 1910s. In describing O. persephone, Berry called it an "exceedingly interesting octopod".
Opisthoteuthis philipii is an octopus of the Indian Ocean. It lives off the coast of Kerala, India. Known specimens were found between 275–365 m (902–1,198 ft) deep in the Arabian Sea near Alappuzha.
Opisthoteuthis robsoni, also known as the deep-water umbrella octopus, is a deep-sea octopus living off New Zealand on the Chatham Rise. It has been found from 1,178–1,723 m (3,865–5,653 ft) below the surface. Not much is known about the octopus' habitat or life cycle, as only four specimens have been found. It occupies the benthic zone, or the seafloor and the water directly above it. O. robsoni eats large amphipods.
Stauroteuthis kengrahami is a species of small pelagic cirrate octopus. It is currently only known from off eastern Australia.
Grimpoteuthidae are a family of bentho-pelagic octopuses, comprising three currently accepted genera. They have extensive arm webbing and relatively large fins allowing for powerful fin swimming.