Hi 1515 SCIENTIFIC AMERICAN °FFOFFPR|NTS•NTS The Giant Squid by Clyde F. E. Roper and Kenneth J. Boss SCIENTIFIC AMERICAN APRIL 1982 VOL. 246, NO. 4 PP. 96-105 • • PUBLISHED BY W. H. FREEMAN AND COMPANY 660 MARKET STREET, SAN FRANCISCO, CALIFORNIA 94104 Copyright © 1982 by Scientific American, Inc. All rights reserved. Printed in the U.S.A. No part of this offprint may be reproduced by any mechanical, photo- graphic or electronic process, or in the form of a phonographic recording, nor may it be stored in a retrieval system, transmitted or otherwise copied tor public or private use without written permission of the publisher. The trademark and tradename "SCIENTIFIC AMERICAN" and the distinctive logo- type pertaining thereto are the sole property of and are registered under the name of, and are used herein under license from, Scientific American, Inc. The Giant Squid This deep-sea cephalopod is so seldom seen, dead or alive, that it seems mythical. Numerous specimens have, however, been studied, and they have begun to reveal the animal's anatomy and its ecology by Clyde F. E. Roper and Kenneth J. Boss In Moby-Dick Herman Melville de- to indicate that as many as five species The giant squid's cylindrical head scribes a sea creature of "vast pulpy live in the Atlantic, two in the northern may reach nearly a meter in length; it mass, furlongs in length ..., long Pacific and several more in the south- is connected to the body proper by a arms radiating from its center and curl- ern Pacific. "neck" bearing a circumferential collar ing and twisting like a nest of anacon- or sheath with a dorsal locking cartilage. das." He apparently had in mind the In 1980 a specimen of medium size— A crown of eight thick, muscular arms giant squid; his description reflects the about 10 meters in total length—was and two very long and thin but muscular meager information that was available stranded on Plum Island in Massachu- tentacles surrounds the buccal (mouth) about the animal in his time. Indeed, setts. The animal was preserved and was apparatus and extends from the anteri- until the crew of a French warship sight- displayed for several months at the New or end of the head. (Cephalopod means ed one in 1861 and managed to haul in England Aquarium in Boston. It is now head-foot.) part of it the animal was quasi-mythical. in Washington at the Smithsonian In- Although the arms are proportionate- Even now, when a considerable number stitution's National Museum of Natu- ly long in young individuals, they are of specimens have been reported, the gi- ral History, where it is being studied relatively much shorter than the ten- ant squid (weighing up to 1,000 pounds in detail. The study provides much of tacles in adults. An arm may attain a and having an overall length of some 18 the data for the following description, circumference of 50 centimeters at the meters, or nearly 60 feet, if the tentacles in which we adhere to the standard meth- base and a length of three meters. Each are extended) remains largely mysteri- od for avoiding ambiguity about ana- arm bears on its inner surface low, ous. No living specimen has ever been tomical positions by relying on the weak and sometimes scalloped protec- maintained in a research institution or terms dorsal for back or top, ventral tive membranes that border two rows of an aquarium. Most of what is known for front or bottom, caudal for at or suckers. The suckers gradually decrease comes from strandings, when the squid near the tail, anterior for forward, pos- in size distally until at the tip of the arm is dead or dying; from capture by fisher- terior for rearward, proximal for near a they are merely tiny knobs. men of animals that soon died, and from reference point and distal for far. The The two ventral arms in males are specimens removed from the stomach normal swimming position of the giant hectocotylized, that is, specialized to fa- of toothed (fish- or squid-eating) whales. squid is horizontal, so that the animal's cilitate the fertilization of the female's On the basis of this information one can dorsal side is at the top and its ventral eggs. With them the male transfers sper- state what a mature giant squid looks side is at the bottom. matophores to the female in mating. like and can say quite a bit about its internal anatomy. On other matters, such as its habitat and method of repro- duction, one can offer only educated guesses based on what is known of relat- ed oceanic squids. Teuthologists, the specialists who study cephalopods (the group of marine animals that includes the squid, the cut- tlefish and the octopus), have placed the giant squid by itself in the genus Ar- chiteuthis of the family Architenthidae. Nineteen nominal "species" have been described, some solely on the basis of individual parts of the animals. Until re- cently the tendency was to classify near- ly every find as a new species. Although authorities differ, it has been suggested that the 19 nominal species can in fact be encompassed by only three: Archi- teuthissanctipauli in the Southern Hemi- sphere, A.japonica in the northern Pacif- ic and A. dux in the northern Atlantic. Some evidence, based mainly on the ADULT GIANT SQUID can be as much as 18 meters (60 feet) long and can weigh as much as relative size of the head and the outline 450 kilograms (1,000 pounds). This drawing is based on numerous specimens or parts of them of the caudal fin, has been marshaled that have been drawn, photographed or preserved over the past century. The squid in the draw- These arms differ among species in their Such reports have led by extrapolation of muscles and as a supporting staff for length and diameter and in the extent of to a distorted estimate of the maximum the elongated body. their modification for the mating func- length of giant squids. The most reliable The multilayered integument that en- tion. Distally the arms bear, as continua- evidence suggests that the average diam- velops the body, the head and the arms tions of the two rows of suckers, two eter of the suckers on the arms is about is a dark purplish red to maroon dorsal- rows of rectangular pads separated by a 2.5 centimeters and that the maximum ly and slightly lighter ventrally. The col- deep furrow. diameter is 5.2 centimeters, the size or of the dorsal and ventral surfaces of The two tentacles, with which the sometimes found on a tentacular club. the arms is less intense than that of the squid seizes its prey in a motion rather lateral ones. The color arises not only like the thrusting and closing of a pair of The mantle, or body, of the giant from a background pigmentation but pliers, are about 25 centimeters in cir- squid is more or less narrowly cone- also from a layer of chromatophores: cumference at the base and can reach a shaped. It tapers to a bluntly pointed pigment-bearing cells that can change length of more than 10 meters. The stalk tail. In adults a short, stout, taillike pro- the coloration of the integument by ex- of a tentacle is bare along the base; alter- jection extends beyond the fins; juve- panding or contracting. In the squid nating small suckers and adhesive knobs niles do not have it. The fins are flexible the chromatophores probably serve to may appear farther along its length. The but not strongly muscular, suggesting modify the color of the integument ac- suckers and knobs increase in size and that they serve as stabilizing vanes. cording to behavioral requirements or frequency toward the club: the slightly As a modification, of the molluscan changes in the amount of light in the expanded distal end of the tentacle. The foot a large, muscular funnel rises ven- water. The internal surface of the man- man us, or palm, of the club has four trally behind the head at the anterior tle and some of the viscera also have rows of finely toothed suckers. The larg- end of the mantle. With it the squid pro- dark reddish pigmentation, an uncom- er medial ones (in two rows) are about pels itself by squirting water out of its mon feature in oceanic squids. Photo- two and a half times the diameter of the mantle cavity. The funnel is highly mo- phores, or bioluminescent organs, are smaller ones in the marginal rows. The bile, so that the squid can dart forward, not known in Architeuthis. diameter of a tentacular sucker may backward, up, down or to the side. In- The giant squid's eyes are enormous, reach 5.2 centimeters. The distal end of side the funnel is a flaplike valve that larger than the headlights of an auto- the club, the dactylus (finger), is pointed prevents the backflow of water between mobile. With a diameter approaching and attenuated but is covered with hun- squirts. Ventrally at the base of the fun- 25 centimeters (10 inches), they are dreds of small suckers. nel on each side is a groove of cartilage the largest eyes in the animal kingdom. All the suckers of a giant squid arc that interlocks with corresponding carti- They are positioned laterally on the shaped like a suction cup. Each sucker is laginous ridges on the inner surface of head and are circular in outline. Each set on a muscular pedicle, or short stalk, the mantle when the squid is expelling eye has an adjustable lens and a dark iris that can be moved by the animal.