$(a)$ Endothermic animal: Birds such as crows, sparrows, pigeons, cranes, etc. and mammals such as bears, cows, rats, rabbits, etc. are endothermic animals.

$(b)$ Ectothermic animal: Fishes such as sharks, amphibians such as frogs, and reptiles such as tortoise, snakes, and lizards are ectothermic animals.

$(c)$ Organism of benthic zone: Decomposing bacteria is an example of an organism found in the benthic zone of a water body.