Gonatidae

Gonatidae
	Berryteuthis magister
Systematics
Class :	Cephalopods (cephalopoda)
Subclass :	Octopus (coleoidea)
Superordinate :	Ten-armed squid (Decabrachia)
Order :	Squids (Teuthida)
Subordination :	Bare- eye squids (Oegopsida)
Family :	Gonatidae
Scientific name
	Gonatidae
	Hoyle , 1886

The Gonatidae are a family of small deep-sea squids . There are approximately 19 known species in four genera , most of which are found in the boreal zone of the Pacific Ocean . However, at least one species lives in Antarctic waters and two other species in the North Atlantic .

description

From a morphological point of view, the species in the Gonatidae family are all relatively similar: All species are characterized by the suction cups on their arms, which are arranged in four rows instead of the usual two. The suction cups of the medial rows of most species are converted into hooks and the tentacles, which are irregularly covered with small suction cups, can also be equipped with a larger central hook. In Berryteuthis magister , for example, only the females have hooks, while the adult members of the genus Gonatus have no tentacles at all.

Only one species, Gonatus pyros , has luminous organs , these are located on the ventral edge of the eyes.

The squid typically have a muscular, cylindrical body with very soft red to purple skin. The arms are thick and their fins vary in size and shape, from arrow-like and half the length of the mantle to kidney-shaped and one-third the length of the mantle. The animals are between 11 and 40 cm tall, but most are smaller than 25 cm. Females become slightly larger than males.

Way of life

The squids live in the pelagic on the edge of the continental shelf , some species even down to 4,500 meters. Their habits have hardly been explored, but it is believed that they embark on time-of-day migrations: during the day they stay in the darker depths of the oceans while at night they come to the surface to use the starlight to search for food. One species ( Gonatopsis octopedatus ), however, has strangely curved arms, suggesting that it belongs to the benthos on the deep sea floor.

Not very much is known about the reproduction of the species in the Gonatidae family. Other squids are known to lay their eggs on the seabed and leave them to their own devices. In Monterey Canyon in Monterey Bay, California , however, five females of the species Gonatus onyx have been observed pulling an egg sac with about 2,000 to 3,000 developing eggs. However, it is not yet possible to say whether this behavior is also pronounced in other types of the family.

The animals feed on both benthic and pelagic species, including smaller fish such as armored cheeks from the superfamily Cottoidea and Koehler , crustaceans such as amphipods and krill and other squids. Cannibalism was also observed.

Many whale species are among the predators of gonatidae, including Black whales , pilot whales , Dall's porpoises and sperm whales . Other hunters include seabirds , northern fur seals , elephant seals and larger fish such as grenadiers , halibut and salmon . In the Antarctic eat Weddell seals , the New Zealand Fur Seal , albatrosses and penguins of Gonatus antarcticus .