82 Sharks: The Animal Answer Guide
end that was blocked by the mesh. Each ray “rapidly learned to use water
as a tool to extract food from the testing apparatus.” Interestingly, all five
started out using only one method, either creating flow by undulating their
pectoral fins or creating suction by “capping the pipe” and flexing their
body. By the end of the trials, they were all using both tactics. So they cor-
rected for their mistakes and adjusted their methods, all of which led to
obtaining the food faster.
In defense of selachian sharks, we would offer that evolution has pro-
vided them, unlike us, with all the “tools” they need for normal activities.
Do sharks play?
Play must have evolved after sharks came on the scene. With a few pos-
sible exceptions, we are unaware of convincing examples of playlike behav-
ior in sharks. But it’s a big ocean.
Some behavior by White Sharks has been interpreted as object play.
Boat crews in South Africa have suspended cloth bags with bait. Known
individual White Sharks grabbed hold of the bag while the crew pulled on
the other end in a sort of tug-of-war, like a dog pulling on the other end
of a sock. The sharks showed no indication that they were trying to eat the
bag or its contents. These sharks also pushed floats around at the surface,
with or without bait present. Is this play or something else? You be the
judge.
Another, more intriguing possibility comes from the Porbeagle, a rela-
tive of the White Shark. Several websites describe apparent play behavior
observed in groups of Porbeagles off the Cornish coast of England. They
are said to roll over and wrap themselves in kelp, to chase other Porbeagles
that have kelp draped over them and bite at the kelp, and to “play” with
objects at the surface such as pieces of driftwood or fishing floats, includ-
ing “passing objects from one individual to another and repeatedly tossing
the objects clear of the water.” We have been unable to find the original
reports of this behavior, and the web reports, all of which are secondhand,
appear to repeat one another.
Do sharks talk?
Sharks, unlike bony fishes, are not known to make sounds. Bony fishes
rub bones together, grind throat teeth, or vibrate their gas-filled swim
bladders. Sharks have neither bones nor gas-filled bladders; grinding teeth
would be possible only in rays or maybe horn sharks. Other than inciden-
tal sounds associated with crushing prey, sharks maintain silence (despite
the roaring sharks that seem to populate many of the grade B shark attack
http://www.ebook3000.com