To understand how mudskippers reproduce, scientists need to get dirty

These leaping, googly-eyed fish mate in mud burrows where they adjust water levels to help eggs hatch.

Studying elusive fish that dwell in dark mud chambers is no easy feat. Thus the science of the many species of mudskippers is incomplete—and some of what’s known is a bit odd. Example: Mudskippers of one sort keep their protruding eyes moist by retracting them deep into their sockets and then popping them out again—hence the genus name Boleophthalmus, or “ejected eye.”

When it’s time for these amphibious fish to breed in the tropical intertidal zones where some of them live, the male stages flamboyant courtship displays, flaring his fins and leaping high into the air. If a female’s impressed, she follows the male to a burrow for procreation away from prying eyes. But thanks to an endoscope, excavation tools, and patient research, Atsushi Ishimatsu of Japan’s Nagasaki University and his team have pieced together a vision of how mudskippers reproduce.

(Watch photographer Thomas P. Peschak discuss photographing mudskippers and whale sharks on assignment for National Geographic.)

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