More Seal Than Otter
An artist's reconstruction of Puijila, swimming.
Swimming Behaviour
Despite its superficial resemblance to an otter, the way that Puijila swam is significantly different from otters. Furthermore, its swimming behaviour is compatible with behaviours in the modern pinniped lineage.
With webbed forefeet and hind feet, Puijila was a highly manoeuvrable swimmer. It used all four limbs to swim. The tail would not have been useful for propulsion.
A northern river otter.
Some otters today are known to swim using their hindlimbs and tail in combination. They kick with their hind feet simultaneously, and coordinate the kicking with undulations of the tail and body.
Modern pinnipeds have flippers, and the groups vary in their swimming modes. The tails of pinnipeds are very small and are not used for propulsion.
- True seals rely on their hind flippers, using them together in a side-to-side movement.
- Sea lions use their foreflippers, "flapping" them like wings.
- The walrus swims using a combination of its fore and hind flippers.
Ongoing research into Puijila may be able to tell us something about evolution of the swimming adaptation in pinnipeds.
A harbour seal.
A Steller sea lion.
A walrus.
