Energy balance as a determinant of two-phase growth in cephalopods
journal contribution
posted on 2023-05-16, 16:00authored byGrist, EPM, Jackson, GD
Many cephalopods exhibit early exponential growth, which abruptly shifts to a much slower rate. Using a simple model of the energy balance between intake from food and expenditure in growth plus metabolism, we consider how the two-phase growth pattern may be explained in terms of energy conservation. We determine the post-hatch size and age at which exponential growth would be expected to terminate. The model is tested with laboratory hatchling data obtained for the giant Australian cuttlefish Sepia apama. Together with growth data obtained for a related species, Sepia officinalis, model projections for critical transition size and age interestingly suggest that the metabolism of S. apama in the natural habitat may be three to four times higher than in captivity. A sensitivity analysis indicates that the critical transition size is in general more sensitive than critical transition time to any invoked changes in metabolic rate.