The term 'dolphin relative' refers to three different species of aquatic mammals: WHALE, ORCA, and PORPOISE. Whales are the largest of the three, and are characterized by their long bodies and blowholes. Orcas, also known as killer whales, are the most recognizable of the three due to their distinctive black and white coloring. Porpoises are the smallest of the three, and are distinguished by their triangular dorsal fins. All three species are closely related and share many physical and behavioral traits.