How do Fish Defend
Themselves From Predators?
Fish have an amazing assortment of defenses. Most fish
hide or use camouflage to protect themselves. But others
use a variety of defenses such as protective spines, electric
shock, chemicals and even venom for protection from predators.
Camouflage creates deceptive appearances and helps animals
avoid detection. Probably the most widely used form of camouflage
among fish is countershading. Most fish have dark backs
and white bellies. The dark back helps them blend in with
the dark bottom or depths when viewed from above, whereas
the white belly helps them blend with the sky when viewed
Many fish are colored to match their backgrounds and, therefore,
appear invisible. This feature is particularly important
for sluggish bottomfish. Some species are capable of changing
their color to match their background, a process called
cryptic coloration. The master of this process is the flounder,
which can quickly change its color pattern to match the
bottom on which they are resting. In the lab, some individuals
have even produced a fair approximation of a checkerboard
when placed in an aquarium with that pattern on the bottom.
Another form of camouflage is colors and patterns that
break up the outline of fish, making them harder to see.
One of the most common patterns of this type is vertical
bars running down each side; this pattern is associated
with fish that live near beds of aquatic plants. The vertical
bars on the fish blend in with the vertical pattern of the
plant stems making the fish difficult to see. Lateral bands,
single dark bands running along the side of a fish, are
most often seen in schooling fish. They may help confuse
predators because the bands tend to blend together making
it difficult for the predator to single out one individual.
The eyes of a fish are perhaps its most visible feature
and frequently the focus of attacks by predators. One of
the most common marks on fish, especially juvenile fish,
is a black spot located near the base of the tail. The spot,
about the size of an eye, serves to confuse predators. The
attacker aims for the tail rather than the head, giving
the victim a greater chance to escape.
Instead of relying on camouflage and confusing markings,
some fish are more offensive in their defense. Poison is
one of the defenses developed by a number of sea creatures.
It may be administered by teeth, spines, or barbs. The scorpionfish,
marine and freshwater catfish, and toadfish are just a few
species of fish that have sacs of poison at the base of
their spines. If a predator threatens the scorpionfish,
it first displays its brightly colored fins as a warning.
If attacked, the scorpionfish moves to pierce the attacker
with its spines and inject it with venom.
Some fish, such as the electric eel and the torpedo ray,
even have electrical properties they use for protection.
These fish can deliver powerful electric shocks through
the water which stun their predators and allow the potential
victim time to escape.
Special chemicals are used by some fish species to warn
others in their group of danger. Minnows release a substance
into the water when they are attacked; other minnows respond
to the chemical by swimming away. Still other fish release
deadly chemicals into the water. The Moses sole, a flounder
from the Red Sea, releases milky poison so powerful that
even sharks are repelled.