Influence of Hydric Environment on Oxygen Consumption by Embryonic Turtles Chelydra serpentina and Trionyx spiniferus

Patterns of growth and metabolism by turtle embryos were examined in groups of eggs incubated on artificial substrates differing in water potential. Snapping turtle embryos in eggs incubated under wetter conditions attained larger size and consumed more oxygen than did embryos in eggs from drier conditions. Mass-specific oxygen consumption, however, was unaffected by hydric conditions of the incubation environment. No differences in growth patterns or oxygen consumption were observed in softshell turtle eggs in either treatment, although eggs on drier substrates lost significantly more mass than did eggs on wet substrates. The temporal pattern of oxygen consumption by turtle embryos resembles that of embryonic precocial birds, but total energetic costs of development in turtles are <50% of predicted costs for precocial birds of similar body mass.