Question

What broad category of animals is primarily ectothermic and covered with scales that facilitate swimming?

Answer 1

fish

Fish show great diversity in body size. They range in length from about 8 millimeters  0.3 inches  to 16 meters  about 53 feet . Most are ectothermic and covered with scales. Scales protect fish from predators and parasites and reduce friction with the water. Multiple, overlapping scales provide a flexible covering that allows fish to move easily while swimming.