The story of a small louse starting its journey on the back of a sea lion.


Picture yourself by the sea, facing the Atlantic ocean.

Know that in the middle of all this hair, you would not see much, as you are in fact a newly hatched sucking louse on the back of a young sea lion. In any case, there is no time to enjoy the scenery of the Argentinian coast. You need to get going, as a great migration awaits you. The back of the sealion pup is great for egg development, being easily dried by the sun, protecting the eggs for humidity, but it’s probably to dry for you to stay on. you are in the middle of giant egg-laying females, but as a sensitive nymph, you must find a cozier place to develop. Following your instinct, as well as other newborn lice, you make your way to the belly of your host, where you will find a place that is more suitable for your hatched self. You enjoy some brief blood meals as you cruise through the hair, holding them firmly in the grasp of your gonopods.

Finally, you arrive in the hospitable plane of the belly, just above the flippers. If everything goes well, maybe you will return to the back of the pup to lay your own eggs someday, who knows?


Leonardi, M.S. et al. (2012) ‘Life begins when the sea lion is ashore: microhabitat use by a louse living on a diving mammal host’, Bulletin of Entomological Research, 102(4), pp. 444–452. Available at: