size and wrestled with it for more than a minute before the
monster finally broke free.
Small, short-lived animals such as skeleton shrimp
are particularly susceptible to boom and bust cycles.
From the look of things, the colony we are investigating
is approaching its population zenith and heading for an
inevitable crash. Such trying times bring out the worst
in any animal, and skeleton shrimp have a lot of worst to
bring out. Predictably, much of the animals’ bad behavior
revolves around sex.
Like other crustaceans, females become reproductively
active immediately following a molt. The process produces
pheromones that drive the males wild. There is no courtship for
these bad boys; the right to pass on genes is settled by a winner-
take-all round of fisticuffs. The stakes are high — a well-placed
claw can slice an opponent in half — and to add to the peril,
each claw is tipped with a poisonous spine capable of inflicting
a fatal wound. The last male standing moves fast, helping strip
away the female’s old exoskeleton in its haste to spawn.
Contrary to the majority of marine creatures, which release
thousands of immature larvae into the open sea during a
single spawn, skeleton shrimp — ever iconoclasts — take the
less-traveled path, producing a small number of offspring
that require extended care. Among the mass of bodies on the
hydroid we can make out what appear to be balls of fuzz. As we
lean closer, the fuzz becomes the limbs, claws and antennae of
several dozen babies clinging to their mother — each an exact
replica of its parent.
From the moment hatchlings emerge from the brooding
pouch and clamber onto their mothers’ backs they are under
siege. And from what we can see, the tykes need protecting.
Baby-toting females, far from pushovers, fight like banshees
to safeguard their offspring. Surviving juveniles grow rapidly,
passing through several molts before they are ready to fend
for themselves. It seemed fitting that toward the end of our
dive Anna noticed a mother flinging her mature babies off
her back with the coldhearted demeanor one would expect
of a skeleton shrimp.
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