Spare Organ Stands In
The story of John Wayne Bobbitt holds no fear
in the earwig world. These well-endowed insects
have a standby Penis to compensate for accidents
in action, Japanese research now shows.
Male earwigs, like a few other well-prepared
animals, carry a spare set of genitals. The
earwig's auxillary organ was thought to be impotent,
as it points the wrong way and females have
only one hole. To probe the workings of the
extra appendage, Yoshitaka Kamimura and Yoh
Matsuo of Tokyo Metropolitan University studied
the earwig Euborellia plebeja. The male of this
species is blessed with a pair of Penises that
are often longer than its body. Kamimura and
Matsuo interrupted the earwigs in the act by
pinching them on the behind.
Pulling a male off its mate broke off his Penis
in its prime. Yet "handicapped males" given
another shot with the ladies still performed,
the researchers found. To see if the earwigs
naturally suffer similar injuries in the wild,
Kamimura and Matsuo collected insects out and
about in central Japan. A few females contained
leftover Penis ends, they found, and the asymmetric
genitals of some males revealed signs of damage.
The findings suggest that both ">Paired penes"
are working organs, says Kamimura; the second
is flexible enough to function despite its misdirection.
"It's an interesting phenomenon," says Mike
Siva-Jothy of the University of Sheffield, UK,
who studies insects' nether regions. He thinks
there must be some evolutionary advantage to
the earwig's "unusually long" and fragile organs.
Breakage may be part of the insect's strategy
to ensure the success of its sperm, Siva-Jothy
speculates. "It's hard to imagine why a male
would do it without a reason," he says, adding
that the end-piece "may act as a mating block."
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