A large number of animals use their colour patterns to blend into their environment. Tree-dwelling animals may be coloured like bark, or may have patterns that help them blend into leaves. Terrestrial animals are often clad in drab shades of brown to help them pass by unnoticed in their dusty/muddy environment. Snow-dwelling animals often have white fur that helps them conceal themselves against the constant wall of white. Many animals possess scattered patches of varying colours that help them blend into the jungle environment; many predators use this technique to great effect. Some animals, such as the pygmy sea horses, have developed incredible colour and patterns that help them blend into their environment. This defensive tactic is called crypsis. Caterpillars employ two types of protective colouring: camouflage and warning. Many caterpillars are coloured just like the plant they grow up on, making them harder to spot for birds and other predators. A large number of snakes are unbelievable masters of concealment and camouflage. The copperhead, one of the deadliest and most notorious snakes in North America, has a stunning pattern of randomly placed blotches on its skin that blends into the vegetation, leaves, and twigs. Thus, protected from detection, it can lie in wait for unfortunate prey to wander its way. All big cats rely on stealth and ambush to catch their prey, and accordingly, need to get as close to their target as they can. Tigers hunt primarily in forested areas; in terrain covered with long grass. Since they usually hunt at dawn or dusk, their otherwise conspicuous stripes allow them to advance unseen through the long grass. Both leopards and jaguars hunt in heavily forested areas (though the former often shares territory with lions and tigers). Their pattern are of great advantage in the ever-shifting shadows in the dappled sunlight. Several animals sport different coats in the summer and the winter. The winter coats of these animals are white, helping them blend in with the omnipresent mass of snow and ice. In the winter, the white coats help these animals either escape from predators or ambush prey. As summer rolls around, the white coats make way for brown-and-black coats, which help the animals hide in the summer landscape. Here are some examples of such animals. Some animals go one step further and actually change their colours at will. The chameleon is, of course, the most famous example of this phenomenon. However, they aren't the only ones who can change their colour; numerous aquatic organisms also have this ability. Like in the case of chameleons, and contrary to popular misconception, these colour changes aren't always for camouflage. Oftentimes, the colours are meant as messages to members of the same species. Changing colours is used to signal sexual availability, or to warn other animals of the same species. Sharks, dolphins, and penguins, notably, have an almost white belly, steadily transitioning into a dark grey-black back. This makes these predators harder to spot from below, where their faint ventral side is hard to distinguish against the sunlight, and above, where their dark backs blend into the dark depths of the ocean. This technique of camouflaging is known as countershading. Animals mimicking an inanimate object, such as a leaf or a twig, can rest around leaves and twigs with their safety virtually assured. Animals mimicking other animals, which is called mimesis, often mimic more dangerous, feared animals than themselves. This gives the weaker mimic better chances of not being attacked. When zebras run together, the collage of the stripes on the zebras makes it difficult for their predators to identify and target an individual. If a single animal strays away from the group, it is indeed easy to pick off, but their pattern gives them better communal odds at survival. This is known as dazzle colouration.