When you look at a vaquita (or any of its porpoise cousins), you might be forgiven for thinking that they might “just” be small dolphins. And while they are related, they are little more than distant cousins. Although both vaquitas and dolphins are toothed whales (suborder Odontoceti), they belong to separate families: the vaquita is a porpoise (family Phocoenidae), while dolphins are members of the family Delphinidae.
The subtle yet significant differences between porpoises and dolphins set them apart. Porpoises are generally smaller in size, with the vaquita reaching an adult length of only about 5 feet (1.5 meters), whereas dolphins, such as the bottlenose dolphin, can grow up to 13 feet (4 meters) long. Porpoises, like the vaquita, possess a more rounded and blunt head, unlike the elongated snouts of dolphins. Furthermore, the teeth of porpoises are spade-shaped, resembling a row of q-tips, while dolphins boast sharp, conical teeth that resemble upside-down ice cream cones.
The genetic divergence between porpoises and dolphins dates back to a split around 15 million years ago when the ancestors of porpoises and dolphins embarked on separate evolutionary journeys. This divergence is comparable to the distinction between somewhat related but distinct terrestrial animals, such as horses and cows. Despite sharing some similarities, their evolutionary trajectories have led them to develop unique traits and adaptations.
While dolphins frequently employ speed and agility to capture their prey, porpoises, such as the vaquita, favor a more clandestine approach, utilizing their keen echolocation abilities to detect even tiny invertebrates like crustaceans concealed in the sand. In contrast to dolphins, which are known for their lively acrobatics, surface antics, and tendency to travel in large groups, porpoises display a more subdued and discreet demeanor. Preferring to avoid the spotlight, they typically gather in smaller groups, underscoring their unique behavioral and social characteristics compared to their vivacious dolphin relatives.