what does ectothermic mean

Ectothermic means an animal relies on external sources of heat (like sunlight or warm surfaces) to control its body temperature, rather than producing enough internal heat through its metabolism like mammals and birds do.

In other words, an ectothermic (often called “cold‑blooded”) animal’s body temperature changes with the temperature of its surroundings, so it warms up by basking and cools down by moving to shade or cooler water.