Whether you prefer to call them dog mermaids, sea puppies, or dogs of the sea, there is certainly no denying that seals bear a striking resemblance to man’s best friend on land. But just because dogs and seals look and behave similarly doesn’t necessarily mean that they are in any way related… Or does it? Are seals related to dogs?
I got to experience this uncanny resemblance firsthand during my recent trip to Duiker Island, Hout Bay, South Africa with Animal Ocean, where my suspicions that seals and dogs are somehow linked only mounted. From their big eyes and whiskered snouts, to their playful and inquisitive personalities (they liked to do somersaults around and nibble on us water humans), the only thing that could differentiate the two species in my mind was a set of flippers. Turns out—I might not have been too far off!
While the exact ancestral link is unknown and widely debated, science can and does tell us that both dogs and seals are members of the same taxonomic suborder of the animal kingdom. Seals, sea lions, and walruses are all considered pinnipeds and belong to the suborder Caniformia (meaning “doglike”). Other caniforms include bears, weasels, pandas, raccoons, and – you guessed it – dogs!
In her book The Pinnipeds: Seals, Sea Lions, and Walruses, Marianne Riedman describes how “millions of years after the first mammal-like animals appeared on earth, several groups of land mammals began to live in the ocean, probably to avoid land predators and to take advantage of the abundant food in an immense and richly productive marine environment.”
This theory was also alluded to by the famous evolutionary theorist himself, Charles Darwin, in On the Origin of Species: “A strictly terrestrial animal, by occasionally hunting for food in shallow water, then in streams or lakes, might at last be converted in an animal so thoroughly aquatic as to brace the open ocean.” In other words, some prehistoric land mammal likely developed physical attributes over time that would enable it to survive in the sea. Appendages, for example, such as limbs and feet may have transformed to the characteristic fins and flippers we now see on modern-day seals.
It is still unclear whether or not seals and other pinnipeds evolved in such a way separately or as a group, but one strong theory suggests that they all diverged from a bearlike or doglike ancestor millions of years ago during their transition to the sea. In fact, as Riedman states, “The skulls of sea lions, bears, and such canids as large dogs and wolves are nearly indistinguishable at first glance.”
So even if scientists claim seals might be more closely related to ursoids (bears) or musteloids (otters) of the suborder than to dogs, I (far from a scientist) am content with the fact that there is at least some slight connection in their family tree. I mean, look at them! You can hardly tell the difference.