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Over 1200 squids were captured by night lighting, trawling, or seining in the northern Gulf of Mexico for laboratory maintenance. Two types of recirculating sea water systems were designed and evaluated: a 2 m circular tank (1500 liter capacity) and a 10 m long raceway (10,000 liters). Mean laboratory survival was: Loligo plei (12 to 252 mm mantle length, ML) 11 days, maximum 84 days; Loligo pealei (109 to 285 mm ML) 28 days, maximum 71 days; Lolliguncula brevis (27 to 99 mm ML) 19 days, maximum 125 days. Smaller squids showed significantly poorer survival than larger ones. All squids fed well on a variety of live estuarine fishes and shrimps. Growth rates depended upon stage of maturity. The highest rates were Loligo plei 59 mm/month (23.8 g/mo), Loligo pealei 77 mm/mo (67.3 g/mo), and Lolliguncula brevis 31 mm/mo (17.2 g/mo). General aspects of behavior and body patterning were species-specific and were useful indices of the squids' condition. Key factors for laboratory survival were (1) prevention of skin damage, (2) tank systems with sufficiently large horizontal dimensions, (3) high quality water, (4) ample food supply, (5) no crowding, (6) maintaining squids of similar size to reduce aggression and cannibalism, and (7) segregating sexes to reduce aggression associated with courtship, mating, and egg laying.

mals, suggesting that these organisms could simply be parasitic (IO, 11). Further work will focus on culturing, identifying, and characterizing the organisms responsible for the DNA sequences found in the bacterial community of the ANG of Lo/igo pealei, and will seek to detect and identify other members of the community. This combination oftraditional culture approaches with molecular analyses provides evidence of a much more diverse bacterial community within the ANG of Loligo pealei than had been observed previously. This molecular approach indicates the presence of different and unexpected bacterial types. Particularly novel is the possibility that phototrophic bacteria may play a role or roles in the ANG. We note that although the molecular data presented are not complete, they permit the formulation of sound hypotheses for further investigation, in combination with the microbiological and physiological techniques essential to develop a reasonable understanding of the composition and function of the ANG bacterial community. We thank members of the MBL Microbial Diversity Course staff and faculty, in particular the Course Directors, E. Leadbetter and A. Salyers, for logistical support and valuable discussions on the project, B. Paster for assistance with molecular analyses, P. Dunlap for discussions on ANG research, and J. Armitage for discussions on phototrophic bacteria. The course was supported by the Office of Naval Research, the Department of Energy, and the Foundation for Microbiology.

Previous behavioral observations of Loligo pealeii revealed the potential for multiple paternity within individual egg capsules, each containing 100 to 300 eggs. Five egg capsules, sam- pled from 3 nearshore locations over 2 yr, were tested for multiple paternity using 3 microsatellite loci. The minimum number of potential fathers was derived from the number of different alleles pre- sent in the progeny. All 5 egg capsules exhibited multiple paternity: genetic markers of at least 4 fathers were found in 2 egg capsules; at least 3 fathers were found in 1 egg capsule, and at least 2 fathers were found in the remaining 2 egg capsules.

Ten prey taxa were recorded from the stomach contents of eight long-finned pilot whales (Globicepbala melas) independently stranded along the U.S. mid-Atlantic coast. Relative importance of prey species was determined by methods that incorporate prey frequencies of occurrence, proportions of numerical abundance, and proportions of reconstructed mass. Separate analyses of trace (free, durable body parts representing well-digested prey items) and non-trace (relatively intact prey specimens) food material were conducted in order to address biases caused by differential rates of digestion and passage through the gastrointestinal tract. Different measures of prey importance yielded varying results, but the long-finned squid (Loligo pealei) was the most important prey species regardless of how prey importance was defined. Fishes were relatively unimportant in the diet. Our results indicate that the diets of western North Atlantic long-finned pilot whales differ substantially from what has been previously reported in the literature and that results from food-habits studies that utilize different techniques may not be comparable.

High-speed ciné recordings of prey capture by the squid Loligo pealei were used to analyze the kinematics of the rapid tentacular strike. The proximal portion of the tentacle, the stalk, elongates during the strike. The non-extensible distal portion of the tentacle, the club, contacts the prey and attaches using suckers. Seven sequences of prey capture filmed at 750 frames s−1 were analyzed frame by frame. The positions of the head, the tentacles and the prey were digitized, and the data were smoothed using quintic natural B-splines and the generalized cross-validation (GCV) criterion. During the strike, the animal swims forward at velocities ranging from 0.7–1.2 m s−1, and as the eight arms are flared, the tentacular stalks elongate. Tentacular extension occurred in approximately 20–40 ms with peak strains in the tentacular stalk ranging from 0.43–0.8. Peak longitudinal strain rates varied from 23–45 s−1. Maximum extension velocities of the stalk were calculated to be over 2 m s−1 with peak accelerations of approximately 250 m s−2. Once the tentacular clubs have contacted the prey, the tentacular stalks are frequently observed to buckle.

The domestic butterfish (Peprilus triacanthus) fishery off the Northeast USA has increased in importance in recent years, to the extent that the quantity allocated to foreign countries fishing within USA waters has been decreased to by-catch levels. This restriction resulted in closure of a portion of the foreign squid fishery in 1985, when the by-catch quota for butterfish was exceeded. This analysis is designed to determine co-occurrence between long-finned squid (Loligo pealei) and butterfish particularly in directed fisheries for each species with a view that areal, diel, and/or seasonal regulations of these fisheries may be feasible to reduce the potential adverse effects of high by-catch rates. Squid and butterfish exhibited high degrees of overlap in temperature and depth preferences as indicated by seasonal and spatial distribution data from research and fishery sources. Commercial fishery data, however, suggested that by-catch of butterfish in the directed squid fishery can be maintained at relatively low levels (

Catch data from research vessel surveys were used to determine if statistical measures of spatial dispersion can be useful in predicting the availability of migratory, schooling species to specific seasonal fisheries. As an example, spring and autumn bottom trawl catches of the migratory longfin squid Loligo pealei were used to calculate three measures of the species' dispersion in the U.S. Middle Atlantic Bight. Commercial catch per unit effort served as an index of longfin squid availability to the inshore (primarily spring–summer) fishery. Results suggested that indices of dispersion for stocks that do not remain within the area of the fishery throughout the year may be more useful in predicting subsequent availability than are indices of relative abundance. The simplest of the three measures examined here–the proportion of tows within a survey yielding no individuals of the species, calculated from the autumn survey data–exhibited a significant negative correlation with the index of availabil...

Stomach contents from 30 long-finned pilot whales Globicephala melas captured incidentally in the Distant Water Fleet (DWF) mackerel fishery off the northeastern United States were examined. Several methods of assessing prey importance were used in order to construct a true representation of the pilot whale diet. Separate analyses of trace (free, durable body parts from well-digested prey) and non-trace (relatively intact prey) food materials were conducted to address biases caused by differential rates of digestion and passage. Squids dominated the diet and long-finned squid Loligo pealei was the most important prey, but we noted large yearly fluctuations in prey importance. Metric multidimensional scaling analyses of trace and non-trace stomach contents of individual whales suggest that many animals were cuaght while feeding opportunistically near fishing operations, resulting in a bias of non-trace (intact) stomach contents. The diversity of prey in this study was greater than previous reports of the food habits of western North Atlantic non-finned pilot whales.

Se presenta una descripción de las principales características, estadios y procesos que ocurren durante el desarrollo embrionario del calamar tropical Sepioteuthis sepioidea a partir de masas ovígeras localizadas en el medio ambiente natural, incubadas en condiciones de laboratorio (salinidad 35 ‰, temperatura 25°C y fotoperíodo de 12 Hr). Se encontró que el desarrollo embrionario de esta especie es similar al descrito para Loligo pealei y Sepia officinalis, con una duración aproximada de 40 días bajo las condiciones de incubación empleadas. Los procesos de blastulación y gastrulación ocupan un 25% del tiempo total de desarrollo de la especie (entre 10 y 12 días) y la organogénesis un 75% (entre 28 y 30 días). A description of the main characteristic stages and processes of embrionic development of Sepioteuthis sepioidea egg clusters collected in their natural enviroment is presented. Eggs were incubated in laboratory conditions (salinity 35 ‰, temperature 25°C, photoperiod 12 hrs.). Embrionic development of this species is similar to that described for Loligo pealei and Sepia officinalis with an approximate duration of 40 days in laboratory. Blastulation and gastrulation processes of the species consumed 25% of the total developing time (10 to 12 days) and organogenesis the last 75% (28 to 30 days).

Like other cephalopods, squid have magnificent visual systems, the development of which has been too little studied in recent times. The structure of the eye (Fig. 1) is described in another chapter (Saibil, 1990), while the adult organization of the optic lobe is well described in Loligo (Kopsch, 1899; Young, 1974). This chapter will review the development of both, and the methods appropriate to that task, in an account drawn entirely from the literature; works on coleoids other than teuthoids are cited only when evidence is lacking in squid and to identify areas in which interesting findings would be forthcoming. The visual system will be interpreted conservatively so as not to include the extraocular photoreceptors in the paraolfactory vesicles, found in squid (Mauro, 1977; Young, 1978); the development of another system of cephalopod extraocular photoreceptors found in octopods, the epistellar body, has already been described (Sacarras:), 1956). The prospects for developmental studies on squid have recently improved with the prolonged culture of healthy animals in captivity (Hanlon, 1990). Squid mating behavior is described for Loligo pealei by Arnold (1962, 1990); embryos are obtained by methods described by Arnold (1974, 1990) and Hanlon (1990). Developmental stages are provided for Loligo vulgaris by Naef (1928), as amended by Meister (1972), and by Arnold (1965a, 1974, 1990) who provides a comprehensive illustrated timetable for Loligo pealei; a table of the events of eye morphogenesis at closely spaced intervals (Marthy, 1973) cross refers to these.

Methodology was developed to measure quality in cooked squid mantle that included sensory evaluation, instrumental texture measurement by use of a modified Kramer shear cell, and physical and chemical properties such as pH, protein release and weight loss. These techniques were then used to evaluate the influence of freezing, refrigerated holding and cooking on the two major North Atlantic commercial squid species, lllex illecebrosus and Loligo pealei. Refrigerated holding produced significant increases in pH of cooked mantle as did longer cook times. Frozen lllex released more soluble protein into the cook water than the other treatments, and longer holding and cooking times produced significant increases in protein levels. Weight losses of over 50% were common during cooking; virtually all the loss could be accounted for as water. Frozen lllex lost the most weight and this parameter increased significantly with both holding and cooking times. Sensory judges indicated texture was a primary quality factor and their most common complaint was a tough or rubbery texture. A sensory index was calculated that provided a single composite score for each sample. This index correlated very significantly with shear values and both parameters were greatly influenced by cooking. Boiling squid mantle reduced shear values and increased quality, probably as a result of thermal gelatinization of the large amount of collagen present in this tissue. The longest cook period (32 min) produced the best sensory quality squid. Holding squid, either fresh or thawed, on ice for up to 5 days significantly reduced quality in lllex but not Loligo; this deterioration likely results from endogenous proteolytic enzymes. Loligo was generally preferred more than lllex in terms of overall acceptability. Kramer shear values were significantly higher for previously frozen samples of both species and fresh lllex toughened during holding. These observations led to amine analysis that showed formaldehyde production, presumably by an enzymatic route from trimethylamine oxide, which could be responsible for protein crosslinking and subsequent toughening.

1. A DFPase has been purified several thousand-fold from the head ganglion and from the hepatopancreas of squid by a combination of ammonium sulfate precepitation, DEAE-cellulose chromatography, gel filtration, and isoelectric focusing. 2. The DFPase from head ganglion is identical with that from hepatopancreas, and is either not found in other species outside the class Cephalopoda , or found in only very small quantities, or is a different kind of enzyme. Although previous evidence suggested a relationship between the squid-type DFPase and the presence of isethionate, the major anion of the squid nerve, the absence of isethionate from squid hepatopancreas now suggests that such a relationship either does not exist, or is, at most, indirect.

The wide range of cholesterol values given in the literature for Loligo pealei and Illex illecebrosus is confusing to people who are designing low cholesterol diets for health purposes. These species were analyzed for proximate composition, fatty acid content, and cholesterol content in order to provide information to consumers and health care professionals. A sampling of both species of squid over a 2-yr period revealed that cholesterol values ranged from about 110 mg up to 450 mg/100g raw tissue with no apparent correlation with season or location of catch. The wide range of values, therefore, seems to reflect natural occurences. Omega-3 fatty acids make up over 50% of the total fatty acids, but these squid, because they are low in fat (about 1.5%), contribute only about 0.5g of these fatty acids per 100g in the diet.

1. This paper reports continued experimentation on factors affecting the survival of the squid, Loligo pealei, in laboratory aquaria. A total of 246 squid were studied in eight separate experiments which were run between May 18 and December 4, 1971.2. Various tank sizes and configurations were studied in conjunction with evaluations of a tank wall bumper system and relative water temperature. Uncontrolled factors such as ambient seawater temperature, age, sex and sexual maturity were studied over the course of the experiments.3. Mean survival of all squid was 177 hours and maximum survival was 1400 hours. In the final design, the mean survival was 248 hours (120 squid). Mortalities in this last group closely followed a log-normal model. The bumper system was found to produce significant survival advantage (with better than 99% confidence) through an analysis of variance of one experiment.4. The "state of the art" is discussed with some generalizations and suggestions for further investigations.

1. 1. Blood pressure and heart rates were measured in unrestrained Loligo pealei . 2. 2. At minimal activity levels systolic and diastolic pressures in the anterior aorta were 7.18 and 2.72 kPa respectively and heart rates were 102 beats per minute. 3. 3. Peak and low pressures in the afferent branchial vessel were 0.92 and 0.04 kPa while mean pressures in the anterior vena cava and efferent branchial vessel were 0.32 and 0.18 kPa. 4. 4. These blood pressures at rest are the highest reported to date for any cephalopod and are probably indicative of the active pelagic existence of these squid.

Giant fiber lobe (GFL) cells obtained from healthy squid reliably produced neuritic processes in culture. The processes were of two types, a sheet-like veil or thin branching neurites. The latter type was often associated with bulbous expansions (presumptive growth cones), at the termini, at branch points, or at sites of apparent contact among branches from two different cells. On poly-L-lysine substrate, veiling usually occurred by the fourth or fifth day in culture, while the branching processes appeared by one week to ten days. The elaboration of the outgrowths by the GFL neurons was influenced by the culture substrate and incubation temperature. The development of a preparation in which isolated GFL somata extend neurites in an easily controlled environment will permit the detailed study of axon fusion, channel expression and turnover, and synapse formation in the neurons.

A detailed kinematic analysis of the mantle movements of swimming Lolliguncula brevis was made. Some data were also obtained on Loligo pealei. The qualitative and quantitative data provided are of use in discussing mechanisms of squid mantle function. Several possible mechanisms of squid mantle re-expansion were proposed and investigated. The inhalant phase of jet propulsion is probably effected by contraction of the radial muscles, since thinning of the mantle wall accompanies re-expansion. The radial muscles may cause mantle re-expansion by contracting alternately with the circular muscles in response to nerve impulses, or by contracting alternately with the circular muscles in response to stretch cycles effected by mantle wall thickening in the power stroke, or by contracting continuously through both power and recovery strokes. Elasticity of the mantle tissue may contribute to mantle re-expansion. Neither pressure pumps nor a Bernoulli effect mechanism are effectors of mantle re-expansion.

The hemocyanin of Busycon canaliculatum contains 0.24 per cent of copper and 15.8 per cent of nitrogen. Its minimal molecular weight is approximately 53,000.The copper content of the hemocyanin of Busycon carica appears to be the same.The hemocyanin of Loligo pealei contains 0.25 per cent of copper and has a minimal molecular weight of approximately 51,000.

Literature dealing with laboratory studies of live squid usually includes a statement that attempts to rear or maintain squid in aquaria are unsuccessful. When stated, the survival of squid in captivity is most often given for the longest lived individual and predictive survival rates are not specified. A considerable body of current research (principally that dealing with squid "giant axons") depends on a reliable supply and short term maintenance of squid. Several aspects of squid biology lag for want of effective means to carry out lengthy laboratory studies. Preparatory to possible future studies on the maintenance of the squid, Loligo pealei (Lesueur, 1821), we have observed squid survival when subjected to standardized conditions. Quantitative data were obtained in an attempt to specify survivorship for comparison with other reports and for evaluation of certain environmental factors. The most dramatic results of attempts to rear cephalopods were reported by Choe (1966), who succeeded in fostering a few individuals of three species for more than 100 days and one loliginid squid for over 40 days. Edward T. LaRoe (University of Miami, unpublished) has repeatedly reared Sepioteuthis sepioidea to near maturity. Adults of this species have been maintained in floating pens for two months and possibly longer (Arnold, 1965). Immature squid, Loligo vulgaris, were reported to survive captivity for several weeks (Bidder, 1950) and for two months (Tardent, 1962). Tardent (1962) stated that sexually mature L. vulgaris do not normally live more than two weeks in the Naples Aquarium. Bidder (1950) reported that L. vulgaris is less sensitive to handling than Loligo forbesi and quoted a Dr. Sereni in the opinion that L. pealei at Woods Hole is far hardier and more resistant to handling than L. vulgaris at Naples. Roper (1965) reported a female Doryteuthis plei which survived 18 days in an aquarium, laying two egg masses in that time. Arnold (1962) gives the survival of sexually mature L. pealei as about five days and one instance of a male surviving for 17 days. These survival times refer to the longevity of the last remaining individual. In all of the references cited, squid were fed regularly and provided with running seawater. Only references dealing with loliginid squid have been cited because the survival of other families of cephalopods may not be comparable due to differences in life habits and ecological tolerances.

The difficulties of working on living squid have caused research into their cardiovascular performance to lag behind that done on octopods. Nonetheless, data that we do possess show squid to have cardiovascular capabilities above those of other cephalopods. In general, heart rate, blood pressure and cardiac output is higher for squid than for the other coleoids andNautilus. This higher circulatory system capability is in keeping with squid being relatively large, fast-swimming, pelagic cephalopods.

Publisher Summary This chapter discusses the cephalopod retinochrome. The cephalopod retina has a dual system of photosensitive chromoproteins with retinaldehyde as chromophores rhodopsin and retino-chrome. Rhodopsin is associated only with microvillar membranes of the outer segments of visual cells, whereas retinochrome is found in both inner and outer segments. The two photopigments differ from each other in the stereoisomeric form of their chromophore retinal, which is 11- cis in rhodopsin but all- trans in retinochrome. Retinochrome can be extracted also from the released fragments of outer segments. In the squid Loligo pealei , it is contained equally in both the inner and outer segments, and in Todarodes pacificus, much more is found in the outer segments. As retinochrome in the outer segments increases markedly during light adaptation of animal, it seems likely that some retinochrome protein moves forward from the inner to the outer segments and reacts there with metarhodopsin.

1. 1. The pH of Loligo hemolymph decreases by 0.021 ± 0.0005 pH units per °C between 5 and 25°C. 2. 2. The change in hemolymph pH with temperature is essentially the same as the change in the neutral pH of sea water over the same temperature range. 3. 3. Buffers with a pH-temperature dependence similar to that of hemolymph are recommended for in vitro studies of squid tissues.

The capture, transport, and maintenance of live adult Atlantic coast squid (Loligo pealei) are described. The objective was to obtain healthy live squid from a coastal region and to maintain them at an inland research facility long enough to provide at least 4 days of electrophysiological research. An inexpensive closed aquarium system is described, which utilizes an ion-exchange resin in the filter, that allows a typical survival time of at least 4.5 days. Similar closed aquarium systems may be of interest to other biophysicists who wish to maintain live squid away from coastal research facilities.

Total, individual weight of squids I. illecebrosus and L. pealei defined by formula, assumes various value in relation to length of body. Coefficient of correlation between length and weight of these species, attains high positive value. Technological output is strictly dependent on length of body.

Specimens of the common Atlantic squid,Loligo pealei, and the brief squid,Lolliguncula brevis, collected from June to September, 1958, in Delaware Bay, were studied morphometrically. Growth rate, length frequency, weight-length ratios, and change of body shape are presented and discussed forL. pealei. Scarcity ofL. brevis made impossible any definite comparison of its morphometry withL. pealei, but certain trends were nevertheless noticeable.