152 Sharks: The Animal Answer Guide
six weeks, which is plenty of time to find another dead whale. Energy-wise,
sharks live in the slow lane.
Do sharks chew their food?
We have to chew our food to make it soft enough and especially small
enough to swallow. The same holds for most animals that can’t bite off
chunks of food. They are “gape-limited,” meaning they are restricted to
eating small, swallowable things. Sharks are among the few fishes that are
not gape-limited because they have the sharp, cutting teeth and strong,
mobile jaws that allow them to tear and cut their prey into sizes they can
swallow. All this is accomplished with the teeth that line the outer jaws,
or in the case of sawfishes and saw sharks, with the teeth along the rostral
“saw”.
So most sharks don’t chew their food, except for the groups discussed
in the next question. Plus one other. Juvenile Lesser Spotted Dogfish cre-
ate swallowable pieces of prey in an entirely unique manner. They anchor
large food items on the pointed scales (dermal denticles) on the top of their
tail, grab the food in their jaws, and pull, thereby tearing off bite-sized
pieces.
How do sharks eat hard-shelled animals?
Food must be small enough and soft enough to swallow and digest.
Some sharks, skates, rays, and chimaeras feed on hard-bodied prey, animals
that have evolved tough outer hides and shells that protect the soft and nu-
tritious stuff inside. Such food types have to be opened or crushed before
they become edible.
Animals that feed on hard-shelled prey are called durophages, phage
meaning “to eat” and duro meaning “tough” or “long-lasting,” so literally,
“eaters of tough prey” (from the same roots as “durable,” “enduring,” and
the battery trademark “Duracell”). Durophagous species have specialized
teeth for crushing the shells of the sea urchins, mollusks (clams, snails,
etc.), and crustaceans (crabs, lobsters) that make up their diet (see “What
kind of teeth do sharks have?” in chapter 2). Durophages, unlike more
usual elasmobranchs, have one of three adaptations to crush their prey: (1)
differently shaped teeth in the front versus the sides of each jaw (Port Jack-
son Sharks, Horn Sharks, Bonnethead Sharks); or (2) multiple rows of flat-
tened teeth in their jaws which create broad surfaces in both jaws that can
be brought together to crush prey (Nurse Sharks, many rays); or (3) fused,
parrotlike beaks (holocephalans).
It is not only the teeth that set durophagous elasmobranchs apart. The
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