Explanation:

An endangered species is a species which has been categorized as very likely to become extinct in the near future. 

The most vulnerable dolphins include the Ganges river dolphin and the Indus river dolphin, which are classified as endangered species, and the Atlantic humpbacked dolphin, which is classified as critically endangered.

Blue whales are baleen whales, which means they have fringed plates of fingernail-like material, called baleen, attached to their upper jaws. Wild dogs have the most structured social order of the carnivores, living in packs led by a dominant male and female.