squid secrets exposed

The breakthrough came after a recent spate of strandings on the Atlantic coast of Spain when five of the huge invertebrates - one of them 12 metres long - were washed ashore in a single week on beaches on the Bay of Biscay.

One of the two males washed ashore was found to have been accidentally inseminated - backing the findings of research in previous strandings.

And scientists now believe the males had either accidentally inseminated themselves during "violent" lovemaking sessions with females or been inseminated by other males after "bumping" into them in the dark depths of the ocean.

The new discovery is reported by a team of Spanish scientists at the Institute of Marine Research in Vigo in the latest edition of the monthly magazine of the International Council for the Exploration of the Seas.

The researchers state: "The giant squid, Architeuthis, is not only a cultural and media icon, but also a scientific enigma. Although it is among the largest living invertebrates ... most of our knowledge of its biology and ecology is still fragmented. So each time a giant squid is washed ashore or gets brought up in a fishing net, it provides a gold mine of information. A recent spate of strandings along the Spanish Atlantic coast has shed new light on their unique sexual behaviour in the ocean depths."

The report goes on: "Although mating has never been observed in giant squid, it is thought that what happens is that the male injects his sperm packages into the female's arms. The process is likely to be a fairly violent affair as the female is probably not that keen on being injected. This is a problem for the amorous male as females are normally a third bigger than they are.

"But males get round their inferior size by being endowed with a particularly long penis, which means they can inject the female without having to get too close to her chomping beak. The male's sexual organ is actually a bit like a high-pressure fire hose and is normally nearly as long as his body - excluding legs and head.

"But having such a big penis does have one drawback: it seems that co-ordinating eight legs, two feeding tentacles and a huge penis, whilst fending off an irate female, is a bit too much to ask, and one of the two males stranded on the Spanish coast had accidentally injected himself with sperm packages in the legs and body. And this does not seem to have been an isolated incident since two of the eight males that had stranded in the north-east Atlantic before had also accidentally inseminated themselves.

"It is also possible that the sperm packages had come from other males that they had 'bumped' into, in the dark depths of the ocean. However, the sperm packages ended up in the squid - it is just another part of the mysterious lives of these creatures of the deep sea."

Fewer than 600 specimens of giant squid have been recorded around the world since the 16th century, with the majority of landings and strandings in the north-east Atlantic and off the coasts of New Zealand and Australia. The giant squid can reach up to 18 metres in length and weigh up to 900kg.

The researchers state: "For many years the race has been on to try to film a giant squid going about its business in the ocean depths, and many marine scientists are vying to get the first video footage. So far all expeditions have been unsuccessful, but a new Spanish expedition is currently being planned and maybe this time we will be lucky."

Animal instincts

GIANT squid are not the only members of the natural world to display unusual sexual behaviour. In Australia, the male Yellow-footed Antechinus - a mouse-like marsupial - goes through such a frenzy of mating that they die of sexual stress. The female praying mantis often eats her partner during or after sex, while homosexual behaviour is also known in geese, ostriches, cichlid fish, rats and monkeys.

• The Scotsman