Poikilothermic animals include types of vertebrate animals, specifically fish, amphibians, and reptiles, as well as a large number of invertebrate animals.
This difference in energy requirement also means that a given food source can support a greater density of poikilothermic animals than homeothermic animals.
But the scientists cautioned that, because sharks were poikilothermic or had a body temperature that changes regularly, temperature was not thought to be regulating the animals' movements.