Sea world and south - A Fascination for Fish: Adventures of an Underwater Pioneer - page 83

Some techniques are developed by chance rather than by plan—as
in the case of the beautiful but aggressively territorial blue-spotted
jawfish ( Opisthognathus rosenblatti ), found north of the Cape in the
Gulf of California. These four-inch fish, like all species of jawfish, are
named for the large mouth they use to brood their eggs and to dig
and construct their elaborate burrows in the gravelly bottom. Excel-
lent structural engineers, they reinforce the sides of their burrow with
interlocking pieces of shell or rock so the burrow doesn't cave in on
them. Materials of just the right size and shape are highly prized, and
they're constantly stealing choice pieces of building material from each
other.
One method we found e¤ective with jawfish takes advantage of their
industrious nature and their habit of constantly working on their bur-
row. A short piece of monofilament fishing line is tied to a small, un-
baited hook. The hook is then dropped down their burrow. Not about
to tolerate a strange object in its home, the fish picks up the hook in
its mouth to remove it. A quick jerk sets the hook and the fish is pulled
out and popped into a plastic bag. The small hook wound heals quickly,
and when placed in an aquarium the fish quickly sets about constructing
a new burrow.
The Gulf of California is home to the world's largest species of
jawfish, appropriately named the giant jawfish ( O. rhomaleus ), which
reaches a size of twenty inches. I learned just how good these fish
were at construction when I attempted to start a burrow for three
jawfish we brought back. With a good assortment of shell fragments
and small rocks I tried to reinforce the sides of a burrow I dug in the
gravel in their new tank. It kept caving in and I finally gave up in
disgust.
The fish, however, soon got to work, picking up pieces of shell and
rock with their mouths to build their own burrows. It wasn't long be-
fore their burrows were complete, with solidly reinforced walls. Most
of the action occurred out of our sight, so we don't know how they do
it, but they certainly deserve an advanced degree in engineering.
Some fishes, we found, were drawn at night to the pool of light sur-
rounding our safely anchored boat. First, assorted planktonic animals
swam toward the light; these in turn attracted small fishes, then larger