Page 56 - Shark

Studying sharks

In the wild, it is difficult to
study sharks because they
constantly move around,
swim too fast, and dive too
deep for divers to keep up
HMS cHallenger with them. Some sharks, like
This British research
vessel took hammerheads, are even scared
19th-century away by bubbles produced by
naturalists to the
Atlantic, Pacific, and scuba divers. To follow sharks,
Indian oceans, where scientists catch them and attach
all kinds of marine
life, including sharks, special tags to their fins. When
were collected. the sharks are released, scientists
can keep track of them
by picking up signals
with a receiver or via a
satellite. Great care is
taken to keep sharks
alive when they are
caught for tagging and
other studies. Certain
types of shark are
Satellite tranSmitting device
By tracking sharks by satellite, captured and placed
scientists have discovered that the in aquariums for
great white swims long distances each
year, such as across the Indian Ocean. observation (pp. 62–63).
data Studying lemonS
store Dr. Samuel Gruber has
studied lemon sharks in
the Bahamas for more
than 10 years. They do
not mind being handled
and do not need to swim
to breathe, so they can be
kept still while scientists
make their observations.
In this experiment
(right), a substance is
being injected into the
shark to show how fast it
can grow. Young lemons
Seabed retriever too can have tiny tags
logging shark presence inserted in their dorsal
fins and are identified
later by their own
personal code number.

getting up a
Shark’S noSe
American scientist
Dr. Samuel Gruber
checks the flow of
water through this
nurse shark’s nose.
Scientists have to
be careful because,
Propeller measuring a although nurse sharks
shark’s swimming are normally docile,
speed is attached to fin they can give a nasty
of a mako shark bite (pp. 18–19).