Marine Mammal Parasite of the Month Answer -November 2021


This parasite is Antarctophthirus microchir and it’s found in sea lions! It’s actually been found in 5 species of sea lion in Australia, New Zealand, North America, and South America. In pups, they are found on the chest and belly primarily, possibly because other areas are too exposed to the sun. Research on adult sea lions is lacking because they are much more difficult to study due to their size. They tend not to be found on the flippers, possibly because sea lions use their flippers to move, and the destructive force of moving would likely dislodge or hinder the survival of the lice. While nesting females and eggs are more often found on the dorsal side (top) of the body, nymphs (young lice), males, and non-nesting females are more often found on the ventral side (bottom) of the body. Fun fact: this parasite only reproduces when its host is out of the water for a long period of time because the eggs and newborn nymphs can’t survive underwater due to their lack of abdominal scales. Reproduction usually occurs during seal lion breeding season when mother sea lions pass on the lice which then reproduces on pups during their first month of life before they start swimming or molting. Growth to adulthood is between 18-23 days with 7-9 days for egg development and 3-4 for the three nymphal stages. Due to the limited time window for reproduction, these lice can only reproduce once or twice a year. In general, the lifespan is unknown, but it likely lives for at least a year in the water.


Posted by fall intern, Adrienne V-H.



Aznar, F. J., Leonardi, M. S., Beron Vera, B., Vales, D. G., Ameghino, S., Raga, J. A., & Crespo, E. A. (2009). Population dynamics of Antarctophthirus microchir (Anoplura: Echinophthiriidae) in pups from South American sea lion, Otaria flavescens, in Northern Patagonia. Parasitology, 136(3), 293-303.

Ebmer, D., Navarrete, M. J., Munoz, P., Flore, L. M., Gartner, U., Taubert, A., & Hermosilla, C. (2019). Antarctophthirus microchir infestation in synanthropic South American sea lion (Otaria flavescens) males diagnosed by a novel non-invasive method. Parasitology Research, 118, 1353-1361.

Leonardi, M. S., Crespo, E. A., Raga, J. A., & Fernandez, M. (2009). Redescription of Antarctophthirus microchir (Anoplura: Echinophthiriidae) from the South American sea lion, Otaria flavescens, from Patagonia, Argentina. Journal of Parasitology, 95(5), 1086-1092.

Leonardi, M. S., Crespo, E. A., Vales, D. G., Feijoo, M., Raga, J. A., & Aznar, F. J. (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), 444-452.

Leonardi, M. S., Crespo, E. A., Raga, J. A., & Fernandez, M. (2012). Scanning electron microscopy of Antarctophthirus microchir (Phthiraptera: Anoplura: Echinophthiriidae): Studying morphological adaptations to aquatic life. Micron, 43(9), 929-936.

Leonardi, M. S., Crespo, E. A., Raga, J. A., & Aznar, F. J. (2013). Lousy mum: Patterns of vertical transmission of an amphibious louse. Parasitology Research, 112, 3315-3323.

Leonardi, M. S. & Lazzari, C. R. (2014). Uncovering deep mysteries: The underwater life of an amphibious louse. Journal of Insect Physiology, 71, 164-169.