''Tremoctopus'' is a genus of

pelagic The pelagic zone consists of the water column of the open ocean, and can be further divided into regions by depth (as illustrated on the right). The word ''pelagic'' is derived . The pelagic zone can be thought of as an imaginary cylinder or wa ...

cephalopods A cephalopod is any member of the molluscan class Cephalopoda (Greek plural , ; "head-feet") such as a squid, octopus, cuttlefish, or nautilus. These exclusively marine animals are characterized by bilateral body symmetry, a prominent head, an ...

, containing four species that occupy surface to mid-waters in subtropical and tropical oceans. They are commonly known as blanket octopuses, in reference to the long, transparent webs that connect the dorsal and dorsolateral

arms Arms or ARMS may refer to: *Arm or arms, the upper limbs of the body Arm, Arms, or ARMS may also refer to: People * Ida A. T. Arms (1856–1931), American missionary-educator, temperance leader Coat of arms or weapons *Armaments or weapons **Fi ...

of the adult females. The other arms are much shorter and lack webbing.

Description

The

common blanket octopus The common blanket octopus or violet blanket octopus (''Tremoctopus violaceus'') is a large octopus of the family Tremoctopodidae found worldwide in the epipelagic zone of warm seas. The degree of sexual dimorphism in this species is very high, wi ...

(''Tremoctopus violaceus'') exhibits one of the most extreme sexual size-dimorphism known in any animal near its size or larger. Females may reach in length, whereas the males are 2.4 cm (1 inch). The weight ratio is at least 10,000:1, and can probably reach as much as 40,000:1. The males have a large arm in a spherical pouch modified for mating, known as a

hectocotylus A hectocotylus (plural: ''hectocotyli'') is one of the arms of male cephalopods that is specialized to store and transfer spermatophores to the female. Structurally, hectocotyli are muscular hydrostats. Depending on the species, the male may use i ...

. During mating, this arm is detached, and kept by the female in her mantle cavity until used for fertilisation. The male almost certainly dies shortly after mating. There is competition between the males; multiple male arms have been found in the mantle cavity of females. The females carry more than 100,000 eggs attached to a sausage-shaped calcareous secretion held at the base of the dorsal arms and carried by the female until hatching. Blanket octopodes are immune to the venomous

Portuguese man o' war The Portuguese man o' war (''Physalia physalis''), also known as the man-of-war, is a marine hydrozoan found in the Atlantic Ocean and the Indian Ocean. It is considered to be the same species as the Pacific man o' war or blue bottle, which is ...

, whose tentacles the male and immature females rip off and use for offensive and defensive purposes. Like many other octopuses, the blanket octopus uses ink to intimidate potential predators. Also, when threatened, the female unfurls her large net-like membranes that spread out and billow in the water, greatly increasing her apparent size. Blanket Octopuses live in coral reefs, where they hunt for food. Their diet consists of smaller fish, and most of their prey can be found in or near coral reefs. They also hide from their predators in the reef, including larger fish and whales. The Blanket Octopus relies heavily on coral reefs, which are facing immense danger due to anthropogenic climate change. The risks these reefs face include coral bleaching and ocean acidification. Although this can be dangerous to the Blanket Octopus because it is their habitat, these creatures are nomadic meaning they can move around and find shelter elsewhere, and they also have the capability to adjust to varying temperatures within the ocean, providing two defense mechanisms that protect them from the effects of climate change.

Species

*''

Tremoctopus gelatus ''Tremoctopus gelatus'', the gelatinous blanket octopus, is a species of octopod formally described by Thomas in 1977. The length of ''T. gelatus'' is unknown. The gelatinous blanket octopus lives in pelagic subtropical waters of the Atlantic Oce ...

'',

gelatinous blanket octopus ''Tremoctopus gelatus'', the gelatinous blanket octopus, is a species of octopod formally described by Thomas in 1977. The length of ''T. gelatus'' is unknown. The gelatinous blanket octopus lives in pelagic subtropical waters of the Atlantic Oce ...

*''

Tremoctopus robsoni ''Tremoctopus'' is a genus of pelagic cephalopods, containing four species that occupy surface to mid-waters in subtropical and tropical oceans. They are commonly known as blanket octopuses, in reference to the long, transparent webs that connect ...

'' *''

Tremoctopus gracilis ''Tremoctopus'' is a genus of pelagic cephalopods, containing four species that occupy surface to mid-waters in subtropical and tropical oceans. They are commonly known as blanket octopuses, in reference to the long, transparent webs that connect ...

'',

palmate octopus The following is a list of terms which are used to describe leaf morphology in the description and taxonomy of plants. Leaves may be simple (a single leaf blade or lamina) or compound (with several leaflets). The edge of the leaf may be regular o ...

*'' Tremoctopus violaceus'',

or violet blanket octopus

Notes

References

External links

* * * * * {{Taxonbar, from=Q1417783, from2=Q18549893 Octopuses Taxa named by Stefano delle Chiaje