Shark Ecology 105
shark immediately left the area and went to Hawaii. How other sharks were
aware of the attack is something of a mystery, although the commotion and
splashing during the attack and the copious amount of White Shark blood
and body fluids in the water could have been detected by other sharks.
By Hiding. Many smaller sharks hide from predators. Some small
night-active sharks spend their daytime resting in caves and crevices, of-
ten in the company of other members of their species (see “Are sharks so-
cial?” in chapter 4). Other sharks, as well as skates and rays, rely on blotchy,
camouflage coloration to make themselves hard to see when they are lying
motionless on the bottom (see “Are any sharks colorful?” in chapter 3).
Wobbegongs also have tassles and skin growths that help them blend in
better with the variable colors and structures of an algae-covered reef. On
sandy bottoms, angel sharks, skates, and stingrays cover themselves with
sand with just their eyes and maybe their spiracles showing, allowing them
to see and breathe while being hard to be seen.
By Defending Themselves. Defending yourself with teeth and
spines is effective, although it means you actually have to battle a predator
that is in all likelihood bigger than you. All but the biggest sharks (Whale,
Basking, Megamouth) have sharp teeth and strong jaws that can deliver an
injury-causing bite. Some species, such as Nurse Sharks, are even flexible
enough to stick their tails in their mouths, which makes pulling the tail of
a Nurse Shark lying on the bottom a very bad idea. Torpedo rays have the
unusual option of defending themselves with their electric shocking equip-
ment.
Many prey species that have good defensive mechanisms advertise the
fact to predators. This makes sense because it’s better to not be attacked or
swallowed, if at all possible. Several stingrays, such as Crossback Stinga-
rees (Urolophus cruciatus), Southern Stingrays, and Shorttail Stingrays raise
their tails and stings above their heads, scorpionlike, when approached by
a diver. We assume that they do the same when approached by a potential
predator. Some torpedo rays advertise their defensive armament by arching
their back and tumbling and twisting in the water, a behavior that may be
a warning display, or may just present the strongest discharge surface to an
attacker. The most colorful electric ray, the Ornate Sleeper Ray of South
Africa, arches its back and raises its tail in what might be a warning to a
predator that it can defend itself with an electric shock.
Skates aren’t as well-equipped as torpedo or sting rays, and their de-
fenses appear to be more passive. A few divers have seen skates roll them-
selves up into balls, curling their pectoral fins down to protect their more
vulnerable bellies and exposing their backs, which are often adorned with