Biology Reference
In-Depth Information
lean too far forward lest one topple over and lose the air-supplying
helmet.
When Marineland first opened they had bottlenose dolphins in with
the fishes in the Oval Tank. This proved to be a mistake. Being highly
curious animals, the dolphins were constantly looking for stimulating
activities. Unfortunately, this frequently involved the unwilling partic-
ipation of the fishes that shared their tank. One activity demonstrated
the ingenuity of the dolphins especially well. A few piles of boulders
had been placed on the bottom of the tank as habitats for California
moray eels (
Gymnothorax mordax
). When the ever-alert dolphins were
cruising above, the eels knew better than to leave the security of their
rock-pile home—something that frustrated the dolphins no end. Also
in the tank were a few California scorpionfish (
Scorpaena guttata
), which
rely on painfully venomous dorsal spines for protection. One unusu-
ally skilled dolphin figured out how to carefully catch and hold a scor-
pionfish in its mouth in such a position that the venomous spines pointed
away from it. Armed with the hapless fish, the dolphin would then poke
at the eels hiding in the rock pile until finally an eel panicked and dashed
out of its shelter. At this precise moment the dolphin dropped the scor-
pionfish and grabbed the moray to play with like it was a brand-new
toy. Experts say that humans, chimpanzees, Darwin's finches, and sea
otters are the only tool-using animals, but this was a remarkable ex-
ample of an inventive dolphin using a living tool for a new purpose.
One of Marineland's pioneering projects was the design and con-
struction of a large fish transport tank that was carried on an eighteen-
wheel diesel tractor-trailer rig. We used it for a major collection of
fishes from Mexico's Sea of Cortez, including gulf groupers (
Myc-
teroperca jordani
), broomtail groupers (
M. xenarcha
), and the giant
totuava (
Totoaba macdonaldi
).
The totuava, the largest of the croaker family (Scienidae), can reach
a length of six feet and weigh over two hundred pounds. Abundant in
the 1950s, the species is now severely depleted owing to overfishing and
the reduction of its spawning grounds. So much water is being pumped
from the Colorado River to supply the people of California and Ari-
zona that little is left to supply the fish's breeding grounds at the mouth
of the river in Mexico.
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