Evidence for this function first came from studies of the organ's anatomy and its nerves ... The coelacanth has gills similar to those of fish living at the depths in which it is commonly found ...

Gases diffuse between water and capillaries in gills, which are immersed in the ... Circulation in the fish is accomplished by a two-chambered heart, whereas a four-chambered heart is used to ...

Fish are cold-blooded creatures, meaning they depend on the sun to stay warm, unlike mammals, which create their body heat.