The Giant Squid: Architeuthis

  • Location: South African Museum
The Giant Squid: Architeuthis

Introduction

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.

Myths and legends

Influencing the movers and shakers in high places, and terrorising the plebs.

Still one of the last great mysteries of the sea, the giant squid 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.

In about 1550 a curious sea-creature, reminiscent of a monk and very large (2.5 m long), was caught in Danish waters and taken to the King. 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 Conrad Gesner 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 Margreta of Navarre, who gave the figure to Rondelet. The sea monster was also reported and illustrated in France (in 1553) by Belon, who apparently had independent sources. In Zürich (in 1558), 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 this popular talk of Steenstrup's was translated and published in English by J. Knudsen of the Zoological Museum, Copenhagen, and M.A. Roeleveld of the South African Museum.

Reconstructing the Soetwater giant squid

 

An important addition to our Aquatic World gallery was to have 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 meters. This animal was 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 that it would have to be as accurate as possible based on the latest squid findings and research. As luck would have it the museum has 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 the details that were lost due to 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 squids 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 margin and head shape. 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?" Compare photo of sectioned specimen, same view of model and Wechsler 1999, fig. 4.

"Which way should the funnel point? i.e. is the squid hovering, going forward or back, 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 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 with most other squids. The two longer tentacles vary between º x and 8x the mantle length, so we made ours long enough to fill the space available - 7.15 metres and at 3.86x mantle length, well within the range. The total length of this model is 9.3 metres.

Text by Martina C Roeleveld

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