The need to eat exposes animals to the danger of being attacked and eaten themselves. To avoid this fate, all animals have physical adaptations that enable them to escape being attacked or to survive an attack once it is underway.
The tulip-tree beauty is a large moth that feeds on the foliage of the tulip tree as a caterpillar. Found from southern Canada to Florida, the moths often have banded coloration that camouflages them against tree bark.
In areas where their ranges overlap, some snakes mimic each another in order to avoid predation. The nonvenomous Sinaloan milk snake (right), for example, closely mimics the color pattern of the venomous coral snake. The strategy is a successful one, as some young, inexperienced snake-eating birds instinctively avoid a pattern of alternating red and yellow rings.
The turtle or tortoise body is encased in a shell made up of a series of bony plates covered with a horny shield. The vertebrae and ribs are fused to the inside of this shell, which gives it additional support and strength. It is impossible for turtles or tortoises to crawl out of their shells. Turtles have a relatively flattened shell and are aquatic, while tortoises have a dome-shaped shell and are terrestrial.
The simplest form of defense is a rapid escape, which calls for keen senses and well-developed systems for movement. Many plant-eating mammals depend on this strategy for survival and must maintain a constant lookout for danger. A less-demanding survival strategy, found in many small animals such as insects, involves deception. These animals use camouflage to blend in with their backgrounds, or they mimic inedible objects such as twigs or bird droppings. If a predator does come too close, they still have the option of making a dash for safety.
The well-camouflaged regal horned lizard, Phrynosoma solare, requires so many ants a day to sustain it that it almost always is found near an anthill. Regal horned lizards usually fare poorly in captivity, where quantities of ants are often insufficient. It remains motionless if approached, but if picked up, it may attempt to disconcert its attacker by puffing up its body and squirting blood, sometimes as far as a few feet, from a reserve behind its eyes. The regal horned lizard is the largest of the American species of horned lizards and can be recognized by the four large horns on the back of its head.
A more sophisticated form of mimicry occurs in animals that resemble species that are poisonous. This is common in insects, and it also occurs in some snakes. Poisonous insects, such as bees and wasps, are often brightly colored to warn other animals that they are best left alone. By adopting these colors and developing similar body shapes, non-poisonous insects benefit from the same protection. The physical adaptations involved can be elaborate. The hornet clearwing moth, for example, is yellow and brown like a stinging hornet. On its first flight, it loses most of its wing scales, resulting in transparent wings that make the resemblance even more convincing.
The snowshoe hare uses camouflage to hide from predators. The summer coat of the snowshoe hare provides excellent camouflage among the grasses and shrubs of its summer habitat, while the white winter coat blends in perfectly with the snowy forest.
An alternative defense, seen in a wide range of animals, uses armor or spines to fend off an attack. Animal armor includes hard shells, overlapping scales, and in the case of armadillos, bands of hardened plates connected by areas of softer skin. If they are threatened, many of these animals can shut their bodies away inside their armor, making them difficult to attack. The disadvantage of this defense is that the animal cannot escape. If its armor is broken open, death is almost certain.