User:Ehaught/Thysanoteuthis rhombus

= Thysanoteuthis rhombus =

Thysanoteuthis rhombus, also known as the diamond squid, diamondback squid, or rhomboid squid is a large species of squid from the family Thysanoteuthidae which is found worldwide, throughout tropical and subtropical waters. This species is commercially fished in Japan, specifically in the Sea of Japan and Okinawa.

Description
Thysanoteuthis rhombus are distinguishable by the presence of arms with two series of suckers, whereas the tentacular clubs have four. It lacks photophores. T. rhombus is named for its fins, which run in equal length along the mantle, giving the appearance of a rhombus. The species is able to grow up to 100 cm (3.3 ft) in mantle length and a maximum weight of 30 kg, although it averages around 20 kg. T.rhombus is not an active swimmer and propels itself slowly using its triangular fins, although the species is able to make powerful contractions of its mantle to escape predation.

The lifespan of T.rhombus is 1 year. Males mature at a mantle length between 400 to 550mm (170 to 200 days) while females mature at a mantle length between 550 to 650mm (230 to 250 days).

Behavior
The species is one of the only cephalopods observed exhibiting pair-like mating relationships. If one member of a male-female mating pair is caught by squid fishermen, the other will likely remain in the area until it is also caught. The species feed the during daytime at deep water levels and during the night at shallow water levels. T.rhombus are often found in small school or pairs.

--long seasonal migrations in oceanic currents

Distribution

Diet
diet: juvenile--> Juveniles feed on crustaceans, small cephalopods and fishes****

Diet: adultnonactive fishes *** at different depths of water

Predation
The predators that feed on T.rhombus include various species of ommastrephid squids, dolphin fish, lancet fish, tuna, swordfish, Gempylus serpens, and sharks. Other predators include mammals such as dolphins, rough-toothed dolphin, false killer whale and sperm whale. ***CITE*** *

Ecology
Life Cycle

The pairing of males and females occurs at an immature stage where mantle length is less than 100mm and pairs remain monogamous. Mating occurs in a head-to-head position, in which the male uses its hectocotylus to attach to the female's buccal membrane to transfer its spermatophores. Spawning is year round in tropical waters, but in temperate regions spawning is more restricted to summer or early autumn periods and warmer currents(*****). Females will produce  secretions of nidamental glands similar to the Japanese flying squid (**THIS HAS 2 DIFF SOURCES) during spawning that will enter the water and swell. This swollen secretion will then be molded by the female into a cylinder. Female's oviductal glands will then begin to form two mucous threads, each with one row of eggs, which will fuse into a single cord containing a double row of eggs in the mantle cavity. The fused cord exits through into the water through the funnel where the eggs are met and fertilized with spermatozoa from seminal receptacles that were attached to the female's buccal membrane. The fertilized egg cord is then wound onto the cylinder.

Commercial Value
firm/flavorful flesh - Japan "Fishing gear such as the free-floating “Taru-nagashi” and “Hata-nagashi” were designed specifically for 'Thysanoteuthis rhombus"****'