'' on the
Davidson Seamount at a depth of 1,328 m '', the boreoatlantic armhook squid These squid are
pelagic, associated with the
continental shelf and may roam as deep as 4,500 m or more, depending on the species. Their habits are poorly studied, but the squid are thought to undertake
diel migration; by day, the squid remain in the blackness of the depths in midwater. By night, they ascend to the upper layers of the water column to feed by starlight. One species, however,
Gonatopsis octopedatus, has curiously recurved arms, suggesting a benthic existence. Little is known about the reproductive cycle of armhook squid. Most squid species whose reproduction has been observed have been seen to deposit eggs on the sea floor, then leave the eggs to hatch on their own. Five female
Gonatus onyx squids have been observed in
Monterey Canyon dragging a membrane sack containing 2,000 to 3,000 developing eggs. It is uncertain if this behavior extends to other members of the family Gonatidae or if it is particular to this species. Prey items include both
benthic and pelagic species, including smaller
fish, such as
sculpins and juvenile
pollock,
crustaceans, including
euphausiids and
amphipods, and other squid.
Cannibalism is also known to occur among the Gonatidae.
Cetaceans are important predators of gonatids;
Baird's beaked whale, the
narwhal, the
short-finned pilot whale,
Dall's porpoise, and
sperm whales are all known to feed upon them. Other predators include large
seabirds,
northern fur seals,
elephant seals, and large fish, such as
grenadiers,
halibut and several species of
salmon. In far southern waters,
Weddell seals and
southern fur seals, as well as several species of
albatross and
penguin, feed upon
Gonatus antarcticus. ==Species==