Animals deploy a wide range of visual techniques to outwit their predators and avoid being attacked - moths and butterflies offer some of the most famous and well-studied examples.
Here are some of the most common strategies:
Camouflage - the art of being invisible
The most widespread form of visual defence, camouflage allows animals to go undetected, blending into the background to escape the attention of predators. While we often think of camouflage as matching the general colour of the natural environment, there are many other ways to be invisible, including patterns breaking up the outline of the animal (known as disruptive camouflage), transparency (for example, in the glass frog pictured) and countershading (being darker on the upper side of the body, concealing its three-dimensional shape).
Masquerade - hiding in plain sight
Another strategy, especially common in insects, is to avoid being recognised as edible prey. These masquerading animals are visible to predators, but avoid being attacked as they resemble unprofitable items, such as leaves (as in this leaf mantis and Morpho butterfly, pictured), sticks or even bird droppings.
Warning signals - beautiful and dangerous
Animals that possess chemical or physical defences often display bright colours and patterns, which act as a warning to predators to stay away. Red, orange and yellow colours, along with contrasting markings, help predators to learn to avoid these distasteful prey more quickly and effectively. Along with butterflies and moths, poison frogs (such as the strawberry poison frog, pictured), coral snakes, bees and wasps are the most famous examples of this strategy. Red and black burnet moths (pictured far left) deter predators with cyanide-based compounds, while cinnabar moths (shown here at the caterpillar stage) store toxic alkaloids from their food plants.
Startle displays and eyespots - scaring predators away
If a predator does approach, some species of moths and butterflies, most famously the underwing moths, deploy a last-ditch defence mechanism. By revealing brightly-coloured hindwings, they startle and confuse their predators, hopefully gaining enough time to escape and settle elsewhere. Eyespots, circular markings often thought to resemble eyes, can be displayed all the time (as in the owl butterfly, pictured right, and the emperor moth, below far right) or used to enhance startle displays (as shown in the peacock butterfly, above far right). These striking markings appear to deter predators, although whether this is because they accurately mimic the eyes of larger predators is still under debate.
Mimicry - a case of mistaken identity
Pretending to be someone else is a very successful strategy for avoiding attack. In some cases, undefended, edible species adopt the colours and patterns of protected species to trick predators into avoiding them, a phenomenon known as Batesian mimicry. In Müllerian mimicry, species that do possess chemical defences share similar warning signals, making it easier for predators to learn to avoid them. Tropical butterflies, such as Heliconius species (pictured, far left) have many mimics, both Batesian and Müllerian, across their range. Other animals may attempt to resemble dangerous animals their predators would prefer to avoid; for example, this large peanut bug, Fulgora laternaria, (left) is thought to deter predators by resembling a lizard rather than an insect.