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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.

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...

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.

SEM was used to reveal progressive structural alterations in the tissue components of cooked squid mantle. Progressive changes were observed at various cook temperatures, 50, 60, 70, 80 and 100°C and after different periods of cooking, 1, 2, 4, 8,16, 32 and 64 min at 100°C. Thermal alterations of connective tissues first appeared as interfibril ‘melting,’ then total fiber gelatinization at higher temperatures. The onset temperatures of ‘melting’ and gelatinization differed depending on the anatomical location of the connective tissue tunics. Thermal alterations of muscle fibers appeared as a loss of myofibril distinction first evident at 50°C. Increasing temperature of muscle fibers caused, in order, coagulation of sarcoplasmic proteins, disintegration of the sarcoplasm, and continuous fiber shrinkage and dehydration. These changes in tissue structure were partially explained by simultaneous changes in gross body dimensions, and mantle pH, moisture, and protein content.

Instrumental tests and profile panel evaluations were used to characterize the textural attributes of squid mantles cooked in water to 50, 60, 70, or 80°C, or cooked for 1, 4, 8, 16, or 32 min after reaching 100°C. A comparison of results from each specific cook treatment was used to interpret textural changes caused by heat and duration of heating at 100°C. Shear type tests, a single blade, and a punch and die, demonstrated that the amount of force and energy required to cut cooked mantles was dependent upon the orientation of the shearing apparatus relative to the direction of muscle fibers and on the side of the mantle initially cut. These anisotropic and nonhomogeneous aspects of the cooked mantle are due to thermal hardening of muscle fibers and to the distribution and heat gelatinization of connective tissues. A unique isometric tension test demonstrated that hydrothermal shrinkage of connective tissues also influenced squid texture. Panel evaluations indicated that two groupings of textural character notes best described texture of cooked squid. Character notes assessing mantle strength correlated with the results of rheological tests. Character notes denoting mantle moisture were not explained by instrumental tests, but were an essential supplement describing the mouthfeel of cooked squid.

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.

As part of a larger ultrastructural study on the photoreceptors of the squid, Loligo pealei, this paper reports findings on non-synaptic regions. The cross-sectional profiles of individual distal segments coincided in horizontal sections as far as 75 μ apart, but progressively less with greater separations. Areas of cross-section showed a unimodal distribution skewed towards 6 μ2, the smallest areas. The distribution of ratios of villous to smooth border was unimodal and skewed with 1.0 being the most numerous and minimal ratio. This ratio tended to increase linearly with area. Cells of small cross-section were completely surrounded by villous border of other cells and about 60° of the perimeter of any cell had microvilli on both sides of the border. Cells participated in odd or even numbers of rhabdomes, up to eight. Pentalaminar membrane junctions between microvilli of the same or neighboring cells were observed. Cytoplasmic microtubules were concentrated near villous borders. In light adaptation some ommin granules entered the photoreceptor tips, and the rhabdomes which formerly began near the surface, now began somewhat below this level. A terminal bar zone existed proximal to the rhabdomes. Here glial cytoplasm separated photoreceptors and both cells contained ommin granules. Photoreceptor somas lacked glial separation and were highly interplicated. Mitochondria were longitudinally arranged along the somal membrane. The planes of the lamellate membrane bodies, seen in the somal cytoplasm of the cells, did not exhibit a rectilinear pattern such as that displayed by the basically rectangular distal segment cross-sections and microvillar orientations.