Under pressure: the extraordinary survival of seal lice in the depth of the sea

MARIA SOLEDAD LEONARDI; JOSÉ E. CRESPO; FLORENCIA A. SOTO; RICARDO B. VERA; JULIO C. RUA; CLAUDIO R. LAZZARI

JOURNAL OF EXPERIMENTAL BIOLOGY

COMPANY OF BIOLOGISTS LTD

Lugar: Cambridge; Año: 2020

0022-0949

Lice from pinnipeds, i.e. sea lions, seals, and walruses, are the only insects capable ofsurviving marine dives. Along their evolutionary history, they adapted to tolerate hypoxia, highsalinity, low temperature and, in particular, to tolerate conditions of high hydrostatic pressure. Tounderstand the limits of the capacity of lice to survive during host deep dives, we conducted aseries of controlled experiments in the laboratory. We collected lice from elephant seals andsubmitted the different life stages to high pressure conditions. Lice were first exposed to one offour hydrostatic pressures: (a) 30 Kg/cm2; (b) 80 Kg/cm2; (c) 150 Kg/cm2, or (d) 200 Kg/cm2.They were then exposed a second time to higher or lower hydrostatic pressure conditions to testfor the impact of the first experience, which could either be deleterious or trigger physiologicaladaption, allowing them a better tolerance to high pressure. We found that lice from elephantseals can tolerate hydrostatic pressures higher than 200 Kg/cm2 (close to 200 atm), equivalent to2000 m depth. Adults exhibited lower recovery times than nymphs after immersion at highhydrostatic pressure. Our findings show that lice developed unique adaptations to endureextreme marine conditions. We discuss these extreme performances as related to themorphological characteristics and physiological responses to diving in these insects.