Metabolic strategy in pelagic squid of genus Sthenoteuthis (Ommastrephidae) as the basis of high abundance and productivity. An overview of the Soviet investigations

The long-term investigations of nektonic squid Sthenoteuthis pteropus and Sthenoteuthis oualaniensis (between 1978 and 1990) have revealed some special features in a metabolism of these animals. These are: (1) rate of energy expenditure is very high (coefficient V in equation Q = aW(k) is from 3.1 to 4.7 at 26degrees to 30degreesC (more than that of other fast swimming animals); (2) hepatopancreatic index is about 4% wet body weight, twice that of actively swimming fishes; (3) protein is the main substrate for energy metabolism; (4) the polyenoic fatty acid 22:6w3 in phospholipids of squid muscle is 42.6 to 45.7% of fatty acids (more than in the most active marine animals); (5) the large proportion of anaerobic metabolism of nitrogenous substances in energy metabolism enables the squid to inhabit zones of very low oxygen concentration

Observations of Multiple Pelagic Egg Masses from Small-sized Jumbo Squid \u3cem\u3e(Dosidicus gigas)\u3c/em\u3e in the Gulf of California

Egg masses of ommastrephid squids are rarely found and not well studied. For the Humboldt squid, Dosidicus gigas, only a single egg mass has been scientifically documented in the wild. Little is known about the size and spatial or temporal distribution of egg masses, or the number of eggs they contain. In this study, we report observations of six egg masses laid in the Gulf of California in May 2015. Egg mass diameters were two to four times smaller in this study compared with the previously observed mass reported in 2008, consistent with the small and large sizes, respectively, of mature female squid captured during each study. Each egg mass contained 17,000–90,000 embryos, one to two orders of magnitude lower than that estimated for the large egg mass previously observed. Egg masses were observed at 9–14 m depth on or near a thermocline. Developmental stages of embryos and paralarvae differed between egg masses. No egg masses were observed in the 13 dives before or the four dives after these masses were found, suggesting that female spawning activity is probably spatially, or perhaps temporally, patchy. Developmental heterochronies in chromatophore development between D. gigas and other ommastrephid squids are discussed. Amphipods and ciliates infested the majority of masses, which is the first documented case of biota associated with wild ommastrephid egg masses