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The giant squid, one of the last great mysteries of the sea, has
not yet been seen alive. A creature of myth
and wonder, an early specimen was described as a merman or sea
monk in 16th century Denmark
Largest of all the animals without backbones, it is a mollusc and
is related to the octopus and cuttlefish, as well as garden snails,
slugs, oysters and mussels.
Habitat
Giant squids are found in all three oceans, mainly in cooler
temperate waters. Until recently their natural habitat was unknown
as they were found mainly from strandings and from the stomachs
of sperm whales. Giant squids are apparently not as rare as previously
thought; with improved fishing techniques and larger trawls, giant
squids are now being caught in trawls, presumably in their natural
habitat. Off the West Coast of southern Africa they have been caught
along the continental slope at depths of 360 m to 620 m and in a
midwater trawl between 18 and 95 m over 4300 m total depth.
Place in the food web
The main predators of giant squids are sperm whales. They are
also occasionally eaten by the Portuguese shark (Centroscymnus coelolepis),
the blue shark (Prionace glauca) and the bigeye tuna (Thunnus
obesus). Juvenile giant squids have been found in the stomachs
of lancetfish (Alepisaurus ferox).
Prey
Like all cephalopods, giant squids are carnivorous, feeding on
crustaceans, fish and other squid. They have a pair of beaks and
a radula, for biting and rasping prey into small pieces.
Prey species recorded from Architeuthis stomachs thus
far are both benthopelagic (Nephrops, Eledone, macrourid
fishes, possibly the orange roughy) and pelagic ( onychoteuthid,
histioteuthid and ommastrephid squids, Trachurus, Micromesistius)
and include fast-swimming fish and squids.
Eggs and juveniles
Giant squid eggs are very small, less than 2 mm long, and very
numerous. A large female may spawn as many as 10 million eggs. Only
a few juveniles have ever been found, the smallest had a mantle
length of only 10 mm. The changes in shape with growth are quite
dramatic but the rate of growth is unknown. Squids generally have
short life cycles and rapid growth and it is possible that a mature
giant squid may be only a few years old.
Size
The giant squid may reach a considerable size. The largest
ever measured was stranded at Lyall Bay, New Zealand in 1887 and
had a total length of 17.4 metres, made up mostly by the 15 metre
tentacles. However, the mantle length of this animal was only 1.8
m, which is a bit smaller than the model on display in the
South African Museum. The largest giant squid in terms of mantle
length (2.8 m) was also stranded at Lyall Bay, New Zealand, in 1878.
Jet locomotion
Like most cephalopods, the giant squid swims by jet propulsion. Water
drawn into the mantle cavity is forcefully expelled through the flexible
funnel, which can move the squid in any direction. |
