Are annelids endotherms or ectotherms?
In the animal kingdom only birds and mammals are endotherms. Their rate of metabolism is greater than all other animals. This metabolism generates heat internally, keeping the organism warm. The heat generated in their bodies makes them independent of environmental temperature fluctuations.
The annelids like earthworm, leech, nereis are ectotherms. Their body temperature fluctuates with temperature of environment. In water, living organisms' temperature fluctuations are comparatively less.