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CEPHALOPODS: Cuttlefish, Octopuses, Squids

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CEPHALOPODS: Cuttlefish, Octopuses, Squids UNITED STATES DEPARTMENT OF THE INTERIOR FISH AND WILDLIFE SERVICE BUREAU OF COMMERCIAL FISHERIES WASHINGTON 25, D.C. Fishery Leaflet 524 September 1961 CEPHALOPODS: Cuttlefish, Octopuses, Squids By Lola T. Dees Branch of Reports Division of Resource Development CONTENTS Page Introduction.... .... ....... ...... .. ...... .. ........ .. .. ....... .. ........ ........... .. 1 Life history. .. ...... .... ..... .. .. .. ....... .... .. ........... ....... ... ..... ..... 1 Description.. ............. .............. ....... ... .. ..................... .. .. ... 1 Food and feeding.. ........ .. ................................. .................... 2 Locomotion..... ............ .. ............. ... ......................... ....... .. 2 Reproduction. .. .. ...... .......... ...... .................. .................. ....... 2 Familiar cephalopods.... .. .. .. ............................................... .. .... 3 Cuttlefish.... .. ..... ................................. .. .................. ... .. ... .. 3 Octopuses.. ................ .. .. ............ .. .. .... ........ ......................... 4 Squids . ...... .............................. .. ................... ... .... .......... 6 Enemies and protection against them. ............................. .............. 8 Capture ............................... .................................................... 8 Utilization..... ................. .. ........ ............................................. 8 References... ................. .......... ............................ ....... .. ..... ..... 9 INTRODUCTION LIFE HISTORY It is true but difficult to believe that the Description cephalopods (argonauts, cuttlefish, nauti­ luses, octopuses, and squids) are related The body of a c ephalopod (meaning feet to such quiet and peaceful mollusks as around the head) c onsists of the head, the clams, oysters, scallops, and snails. trunk, and the neck which connects the About 600 genera and more than to,OOO head and the trunk. The large head contains species of fossil cephalopods h~ve been two conspicuous and well-organized eyes described (Clench, 1959). Today, however, and usually a cartilaginous brain case. there are about 170 genera and more than Around the front of the head, cephalopods 400 species of these marine animals. have a group of elongated muscular arms ) with suckers on the undersides. (FeInales Locomotion and Inales have the SaIne nUInber of arInS, which regrow if cut off.) Inside the circle The cephalopods have several Ineans of of arInS is the Inouth, with two horny jaws, l ocoInotion. SOIne walk on the ocean floor called a beak, and a radula, a file like with their a r Ins . Others swiIn slowly by device . In addition, there are well-developed waving the fins while holding the body organs of hearing and sInell. horizontal, as do fish. All can Inove rapidly The trunk, the Inain part of the body, is by expelling water froIn the Inantle cavity surrounded by the Inuscular Inantle. The through the siphon. Bending the siphon Inantle encloses a large cavity with the two backward sends the aniInal forward; well-developed gills . The digestive tract, however, the siphon is norInally directed kidneys, and reproductive systeIn open into forward so t hat rapid spurts of Inove­ the Inantle cavity. The outlet of the Inantle Inent b,ackward are Inost character­ cavity is through the siphon, a short InUSCU­ istic. lar tube b eginning in the neck. Through it a re expelled the body wastes, the eggs, and t h e fluid froIn the ink sac. Water entering Reproduction th Inantle cavity through the siphon carries oxygen to the gills. All cephalopods except The sexes are separate, and the repro­ Nautilus, hav e an ink sac which cont ains a duction systeIn is cOInplex. One of the deep-brown fluid. a rInS of the Inale of Inost cephalopods is The Inajority of the cephalopod s have Inodified to transfer sperIn to the feInale. fins. With the Inodified arIn the Inal e takes the The skin contains Inany chroInatophores sperInatophores (a special capsul e , packet, (cells containing pigInent, which includes or Inass, enclosing sperInatozoa o r sperIn black, brown, and reddish yellow ). The cells) froIn his Inantle cavity and p l aces color of the body i s changed a t will by theIn in either the Inouth or the Inantle contracting and expanding the chr oInato­ cavity of the feInale . This action ends his phores. The color changes are believed to part in the breeding process . If h e places afford protection froIn eneInies , to help the sperInatophores in her Inouth, she catch prey, and perhaps to express certain Inoves theIn to her Inantle c avity. In the eInotions . Many pelagic and deep-sea Inale argonaut the Inodified arIn i s de - \... cephalopods possess lUIninescent organs. tached and left in the Inantle cavity of SOIne of the cephalopods have external the feInale with the sperInatophores shells while others do not. Nautilus, the Inost (MacGinitie and MacGinitie, 1949). In the priInitive living cephalopod, has a shell squids only the tip of the Inodified arIn into which it Inay withdraw it s entire body. is detached. The feInale argonaut has an e xte rnal shell, The sperInatophores r elease sperInatozoa secreted by a pair of ann s Inodified for which fertilize the eggs . The feInales of the purpose. In the course of evolution the different species lay eggs which vary other cephalopods lost the protective ex­ in size. The eggs pass through the siphon t e rnal shell, but gained speed and Inobility. into the water . They a r e usually fastened down singly or in clusters on bottoIn debris, Food and feedine; such as fragInents of coral or steInS of plants . So far as known, only the feInale All cephalopods feed on other aniInals octopus tends her eggs until they hatch, of the sea, preying on fishes and crusta­ and this Inay take as long as 4 Inonths ceans, such as crabs, prawns, and shriInps . (MacGinitie and MacGinitie, 1949); she Squids will even attack and eat injured does not feed during this tiIne . Squid eggs IneInbers of their own species. (fig. 1) do not require this care because These aniInals catch and hold prey with they are eInbedded in jelly. Besides pro­ the arIns. They sOInetiInes thrust the radula tecting the little eInbryos froIn fungus against the body of the victiIn and rasp growths, the jelly is distasteful or inedible the flesh. Usually, however , they bite into to Inost aniInals. Fertilized eggs of the the prey with the sharp beak and cut out cephalopods hatch into young which are wedge -shaped portions of flesh which they es sentially siInilar to the adult; developInent swallow whole. is gradual and direct. 2 l Figure 1.--Squid eggs (Loligo pealei). Courtesy of Robert K. Brigham. FAMILIAR CEPHALOPODS are four rows of suckers down the entire length of the arms, except on the male's The most familiar living cephalopods fourth arm on the left, where they are are the cuttlefish, the octopuses, and the absent toward the base. The pair of tenta­ squids. cles h a s suckers only on the club-shaped e nds. The calcified cuttlebone (fig. 2), the Cuttlefish m ost characteristic feature of the cuttle­ fis h, lie s in the dorsal (back) portion of the About 100 speciel!J of cuttlefish (family mantle cavity. Sepiidae, group Decapoda) are known. They O r dinarily cuttlefish rest horizontally are found in mOl!Jt tropical and temper ate on o r near the sea floor, with their fins seas but only rarely in northern waters. gently waving, the tentacles withdrawn into They mainly inhabit shallow coastal pockets beneath the eyes, and the arms . waterl!J. depreue d . Thel!Je animals have a l!Jomewhat flattened The best known species of the cuttlefish body edged by a pair of rather narrow fins . i s Sepia offioinalis (fig. 3) of the Mediter­ Five pairl!J of arml!J encircle the mouth. One r anean. Ov al in I!Jhape and with a slightly pair (tentaclel) is longer than the rel!Jt. The flattened l!J urface, it attains a length of 6 to a rml!J are equipped with lucke rI!J which are 10 inche l!J. Its color ul!Jually ranges from stalked, with horny riml!J that may be pale g ray to dar k b r own or neutral tints. saw-toothed. On the shorter arms ther e Sometimes it has zebralike stripes. ) 3 tic waters . They are found chiefly in shallow coastal waters, but some occur at great depths . The octopus (fig. 4) has a large head w ith a strong beak, and a small oval saclike body with an internal shell (a pair of vestigial structures to which muscles are attached) but no fins . The eight long, slender arms are of equal length and more or less united at the base by a thin mem­ brane. Two rows of cuplike suckers, one of its d istinguishing characters, extend the full length of each arm. The suckers are without stalks and without horny rims. The third arm on the left -hand side in the male i s modified for sexual purposes. Octopuses are solitary; that is, they do not live in groups . Ordinarily they live on the bottom of the sea among rocks . They hide in holes or in underwater caves, with their arms reaching out to seize victims . The position of the arms at this time reveals their hiding place. Sometimes an octopus digs its own den. It moves large stones to make the den and closes the entrance with stones when it moves inside . A pile of empty mollusk shells often marks the entrance of the den. There are numerous species of octopuses . Some species spread their arms from 12 to 14 feet . Ordinarily, however, the octopus does not attain one-half these dimensions, a nd many species have bodi es no larger than an orange . The common octopus alonJ the southern coast of Californi a i s Paroctopus bimaculatus . Farther north lives Octopus Figure 2. --Cuttlebone of the cuttlefish (Serw offi c <naltsj. apollyoll which has been known to have a Courtesy of the American Museum of ,vatural Hi s torv. diameter of 28 feet. O. punctatu.'J, also of the Pacific c oast, is said to r each 14 feet in length when the a r ms are outstretched. O. vulgaris of the Mediterranean and the temperate Atlantic reportedly attains a length of 8 feet and an arm spread of about 18 feet. O. bairdi is found on the Atlantic coast north of Cape Cod, where it is never particularly abundant.
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