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.
The largest of all animals without backbones, it is a mollusc, related to the octopus and cuttlefish, as well as garden snails, slugs, oysters and mussels.
Giant squid 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 squid are apparently not as rare as previously thought; with improved fishing techniques and larger trawls, they 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 to 620 metres, and in a midwater trawl between 18 and 95 metres over 4 300 metres total depth.
Place in the Food Web
The main predators of giant squid 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 squid have been found in the stomachs of lancetfish (Alepisaurus ferox).
Like all cephalopods, giant squid 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 other squid.
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. Squid generally have short life cycles with rapid growth and it is possible that a mature giant squid may be only a few years old.
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 of the 15-metre tentacles. However, the mantle length of this animal was only 1.8 metres, slightly smaller than the model on display in the South African Museum. The largest giant squid in terms of mantle length (2.8 metres) was also stranded at Lyall Bay, New Zealand, in 1878.
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.
Myths and legends
Influencing the movers and shakers in high places, and terrorising the plebs.
In about 1550, a curious sea-creature, reminiscent of a monk and very large (2.5 metres long), was caught in Danish waters and taken to King Christian III. At that time Denmark had recently undergone the Reformation and the establishment of the Protestant Church. Monks were not very popular, so the King ordered that the abominable creature be buried, lest it provide a fertile subject for offensive talk! But first the King had the sea monk illustrated and sent to Guillaume Rondelet in France, for inclusion in his big work on fishes, Libri de Piscibus Marinis, published in 1554.
Another account of the sea monk reports that the drawing was sent to the Emperor Charles V in Spain. As a result, King Christian was included in the 1550 alliance between the Emperor and the Scots. The nobleman who handed over the illustration to the Emperor gave a similar one to the illustrious Queen Margaret of Navarre, who gave the figure to Rondelet. The sea monster was also reported and illustrated in France (in 1553) by Pierre Belon, who apparently had independent sources. In Zürich (in 1558), Conrad Gesner received a drawing and description very similar to those of Rondelet. Gesner also received another drawing of the monster from an independent source. This report said that the King had sent the drawing to the Duke of Mecklenburg, from whom a drawing reached the Council in Lüneburg. So the Danish Sea Monk was known all over Europe.
The sea monk was described as having a human head, shaven like that of a monk. Its clothes were made of scales, like a monk’s cloak. It had two long fins instead of arms and the lower part ended in a broad tail.
In a popular lecture to the Danish Natural History Society in 1854, the eminent biologist Japetus Steenstrup showed that the sea monk was actually a squid. Furthermore, the large size of the sea monk indicates that it must have been a giant squid – Architeuthis.
In 1980 Steenstrup’s popular talk was translated and published in English by Jørgen Knudsen of the Zoological Museum, Copenhagen, and MA Roeleveld of the South African Museum.
Reconstructing the Soetwater giant squid
An important addition to our aquatic world gallery was an example of a giant squid. It was decided that a model would be built based on a mature female, with a mantle (body) length of 1.85 metres, which had been stranded at Soetwater, near the Slangkop Lighthouse at Kommetjie, after a storm in March 1991. The museum’s taxidermy section would undertake the model and ensure that it would be as accurate as possible based on the latest findings and research. As luck would have it, the museum had a resident squid specialist who would provide the necessary scientific background and expertise.
Reconstructing the Soetwater giant squid involved a lot of research, to fill in details that were lost due to the damage of the specimen. Sources of information included records and photographs of other specimens collected in recent years. Still, none of the South African giant squid had intact tentacles, which may reach a length eight times that of the mantle. Even the eight shorter arms were incomplete in all our specimens.
For information on the tentacles, specimens were examined in other museums overseas. Architeuthis tentacles seen in museums in Denmark and Norway were photographed and measured, reconstructed and enlarged to a size appropriate for our large female.
We also delved into the literature, going back to the 1880s, for details and reconstructions of animals stranded in places as remote as Newfoundland and New Zealand, and found that many of the drawings and models of giant squids are inaccurate. Most models show arms that are too thin, the funnel too far forward, eyelids the wrong shape and inaccurate anterior mantle margins and head shapes. We also had to take some guesses, as the eyeballs collapse and the head sags after death.
Our first step in constructing the model was to draw scaled-down drawings of a reconstructed Architeuthis, based on measurements taken from the Soetwater female.
This prompted questions such as:
‘Is the mantle round in cross section?’ We decided that a slight oval, wider than high, would look more natural than completely round.
‘How wide are the arms, and what is their shape in cross section?’
‘Which way should the funnel point? That is, is the squid hovering, going forwards or backwards, fast or slow, catching prey or cruising or just hanging there?’ We wanted to make as few assumptions as necessary, so the funnel points down as if the squid is hovering and gently breathing in and out.
‘Where is the eye placed in relation to the arms – how high and how far forward?’
‘How long are the arms and tentacles?’ The arms are about the same length as the mantle, or slightly longer, which is very long compared to most other squid. The two longer tentacles vary up to 8 times the mantle length, so we made ours long enough to fill the space available – 7.15 metres and at 3.86 times mantle length, well within the range. The total length of this model is 9.3 metres.
Text by Martina AC Roeleveld.