The role of temperature and maternal ration in embryo survival: using the dumpling squid Euprymna tasmanica as a model

The embryonic phase and its implication in the hatchling size and condition of Atlantic bobtail squid Sepiola atlantica

“…The duration of development was similar to that observed by Boletzky (1983) in Sepiola robusta. However, the mean time was 50% lower than in the sepiolidae Euprymna tasmanica reared at the same temperature (18°C, Steer et al 2004). Hatching lasted for 23 days in S. atlantica at a mean temperature of 14.4°C in northern Welsh waters (Jones and Richardson 2010), which is comparable to our results at 18°C.…”

“…Larger hatchlings are supposed to reduce susceptibility to predation (Steer et al 2003) and starvation due to enhanced swimming ability and predatory competence in comparison with smaller hatchlings. This trade-off has been identified in different animal taxa, such as lizards (Svensson and Sinervo 2000), many marine invertebrates (Marshall and Keough 2007 a review) and cephalopods (Laptikhovsky and Nigmatullin 1993;Steer et al 2003Steer et al , 2004; see also Boletzky 2003b and Villanueva and Norman 2008 for reviews). Moreover, differences in egg size and hatchling size seem to reflect ecosystem fluctuations, mainly temperature and food availability, such as those found during different spawning groups in the squid Illex argentines (Laptikhovsky and Nigmatullin 1993).…”

“…In contrast to many other marine invertebrates (references in Marshall and Keough 2007), there is very little information on how maternal conditions affect the hatchling condition in cephalopods (Boletzky 2003b;Steer et al 2004). Therefore, it is beneficial to investigate whether egg size is a determinant of hatchling size in S. atlantica and whether temperature has an effect on this trait.…”

Protein Synthesis, Degradation, and Retention: Mechanisms of Indeterminate Growth in Cephalopods

“…In contrast to other molluscs, Euprymna had values that were well below the nearly 100% protein synthesis retention efficiency value recorded for Octopus (Houlihan et al 1990). It is worth noting that Octopus and Euprymna have dramatically different life-history characteristics: Octopus are terminal spawners (Semmens et al 2004), while Euprymna are multiple spawners (Steer et al 2004). The faster specific growth rate (SGR) observed in the younger/smaller individuals compared with in the older/larger individuals was a function of greater protein synthesis retention efficiency, faster fractional rates of protein synthesis, and, to a lesser extent, the concentration of RNA in the tissues.…”

“…It is hypothesized that slow rates of protein degradation in Octopus vulgaris may occur because the loss of function associated with retaining damaged protein is outweighed by the advantage of increased size and reproductive capacity, thereby allowing optimum use of proteins for accretion over their short life spans (Houlihan et al 1990). Euprymna tasmanica did not appear to have similarly slow rates of protein degradation, but unlike O. vulgaris, Euprymna is not a terminal spawner: a female produces multiple batches of eggs throughout her lifetime (Steer et al 2004). Therefore, the faster rates of protein degradation and less efficient protein retention in Euprymna may be a mechanism to extend tissue function.…”