For us terrestrial bound land-lubbers, going under the coastal waters of the eastern Pacific can be daunting; it is cold and quite dark! However, this is not a problem for harbor seals (Phoca vitulina) and other pinnipeds (i.e. seals, sea lions, and fur seals), who have sensory adaptations to thrive in this dark and murky environment! In addition to large eyes, seals also have extra rods (the photoreceptor cells that we, and other animals use to detect changes in light) compared to humans, as well as a tapetum lucidum. This is a fancy, fun word that describes a layer of reflecting plates behind the retina that mirrors any light back through the eye to double the power of the seals’ rods!

[Photo and caption by Karli Chudeau]

Riedman, M. (1990). The pinnipeds: Seals, sea lions, and walruses. University of California Press.

[Edited by Maggie Creamer]