Foods and Feeding 143
to immobilize it while taking bites. A pointy-nosed shark probably would
have slid off the ray’s back, but the hammerhead was able to apply pressure
to both pectoral fins at the same time.
The rostral saw of the pristid sawfishes is an impressive weapon. As
the defining characteristic of the family, it isn’t surprising that the saw has
multiple uses depending on circumstances. Although direct observations
are surprisingly limited, sawfishes appear to vary the way they use their saw
depending on prey type, location, and behavior (ignoring for the moment
that the rostrum is studded with electroreceptors that the sawfish probably
uses for finding buried prey):
■ Sawfishes swing their head back and forth in rapid lateral swipes, stun-
ning or dismembering prey fish. This technique is said to allow them
to enter a school of fish and whack a couple. On videos, the back-and-
forth swinging is just a blur. Damaged prey (incapacitated and even de-
capitated) are suctioned up in the water column. If a mullet or her-
ring gets impaled on one of the rostral teeth, the sawfish scrapes it off
against the bottom and eats it.
■ If the prey dives to the bottom, the sawfish pins it there under the saw,
swims forward, and suctions it up.
■ Sawfishes reportedly also use the saw as a digging tool to unearth bur-
ied crustaceans. Observations of this particular behavior are rare and
anecdotal, and the most thorough study of feeding in any sawfish
species, using juvenile Largetooth Sawfish, did not observe this activity.
Sawfishes do defend themselves readily with the saw, including striking
small boats that follow too closely and persistently in shallow water.
The Salmon Shark, a close relative of
the White Shark, is found chiefly in
the cooler waters of the North Pa-
cific. It feeds primarily on fish, espe-
cially salmon—hence, its common
name. Both jaws contain the long,
spiky teeth characteristic of fish-
eating sharks. Photo from http://www.afsc.noaa
.gov/race/media/photo_gallery/photos/
Lamnidae/salmsharkcls.jpg