Animal Species:Southern Giant Squid – Architeuthis dux
This genus is often referred to as ‘Monsters of the deep’. Giant Squids are the largest of all the living cephalopods and the largest individual invertebrate in the world. There is still little known of the identity, distributions, biology and behaviour of giant squids.
Standard Common Name
Southern Giant Squid
Two thirds of the length of these squids is made up by a pair of long feeding tentacles each bearing an elongate club on the tip. These metre-long tips bear large suckers armed with toothed horny rings.
Body to at least 2m, total length to at least 15m. Little is known of size range of this species due to the limited number of observed specimens, although it is reported to weigh up to at least 220kg.
The family Architeuthidae contains a single genus, Architeuthis. The number of species of giant squid is not known although the general consensus is that there are three species; A.dux found in the southern ocean, A.dux in the Atlantic Ocean, and A.martensi in the northern Pacific Ocean.
Southern Ocean, exact distribution unknown but individuals have been captured by deep-sea trawl fishing off New Zealand, Australia, and South Africa.
The deep, dark, cold waters of the open ocean - this species has been captured from depths of 400-800m.
Feeding and Diet
The stomach contents of some specimens have contained pieces of fin rays from large fish and squid suckers almost as large as their own. It is thought the prey is torn into small pieces by both the large beak and their large toothed tongue, or ‘radula’.
Other behaviours and adaptations
The fins of the Giant Squid are small, and the muscles appear to be poorly developed - so it is unlikely that these squids are fast swimmers. It is believed the animal’s buoyancy is aided by pockets of ammonia solution within the body walls.
Mating and reproduction
Little is known of the breeding behaviours of Architeuthis dux, except for information provided by one female specimen caught off Tasmania in 1996. Numerous ropes of sperm were found radiating from a single point of entry in the skin, which is akin to many other squid species that store sperm in special receptacles or within their skin. It is also known that male Giant Squids have a muscular, well developed penis up to a metre long. It is thought from these two pieces of evidence that males use their penis almost like a hydraulic nail - inserting cords of sperm into the females skin. The female would then store the sperm until her eggs are fully developed and ready to be fertilised- although it is unclear how she might access the stored sperm.
Predators, Parasites and Diseases
Sperm whales are known to feed on the Giant Squid, as the squid beak has been commonly found in the stomachs of beached sperm whales.
R. Ellis. (1998). The Search for the Giant Squid – The biology and mythology of the world’s most elusive sea creature, Penguin Books, New York.
Norman, M., (2000) Cephalopods- A World Guide, ConchBooks, Germany (Hackenheim)
Norman, M & A. Reid., (2000) A Guide to Squid, Cuttlefish and Octopuses of Australasia, CSIRO Publishing, Victoria (Collingwood)