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 flamboy-
ant 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.
The male builds a burrow to serve as a nest. One or more shafts
lead to a chamber that fills partly with water but has a domed ceil-
ing to hold an air pocket. The female deposits eggs on the ceiling,
and the male fertilizes them. Once she departs, he tends the eggs
for their few days of gestation. To maintain the oxygen the eggs
need, the male will swim to the surface, gulp air, bring it back, and
exhale, over and over. Watching video that Ishimatsu made with
the endoscope, his colleague Karen L. M. Martin deduced that a
male might take “roughly 100 mouthfuls” to create the air bubble.
Then somehow, Martin says, the expectant male “keeps track of
tide and time”—and at the right moment, he begins gulping the
air in the burrow and blowing it out. Water pours in, triggering the
larvae to hatch; they swim up from the burrow and away. The male,
Martin says, is “really a very good papa.” —PATRICIA EDMONDSFOR HIS
OFFSPRING,
THIS DAD
GIVES THE AIR
HE BREATHES
PHOTOGRAPH BY
THOMAS P. PESCHAKA few dozen species of
mudskippers live in mangrove
and tidal-zone ecosystems
around the world, including
on Kuwait’s coast, where
it took veteran National
Geographic photographer
Thomas P. Peschak “many
hours of lying motionless in
the mud to photograph the
courtship rituals” of the fish.EXPLORE | BASIC INSTINCTS