Some insights into the thermoregulation strategies of Amazonian caimans from ingested temperature sensors and thermal imaging

We investigated the body temperature of three captive caiman species Paleosuchus palpebrosus, Caiman crocodilus and Melanosuchus niger. These are all inhabitants of the Amazonian basin and share an ecto-poikilothermic metabolism typical of extant crocodylians. In the wild, these species occupy different habitats and have distinct ecological requirements that relate to their size differences, which range from the world’s smallest caiman species P. palpebrosus to M. niger that may exceed 5 m in length. We confirm that P. palpebrosus is a thermoconformer whereas C. crocodilus and M. niger are active thermoregulators. It appears that there are correlations between the kinds of habitats occupied by each species and their thermoregulatory strategies. Furthermore, we provide some data showing that the two thermoregulating species use the extended vascular network of the skull and dorsal osteoderms to store heat.