Monkey mandrill, almost long and weighing up to . Some are arboreal (living in trees) while others live on the savanna; diets differ among the various species but may contain any of the following: fruit, leaves, seeds, nuts, flowers, eggs and small animals (including insects and spiders). Some characteristics are shared among the groups; most New World monkeys have prehensile tails while Old World monkeys have non-prehensile tails or no visible tail at all. Old World monkeys have trichromatic color vision like that of humans, while New World monkeys may be trichromatic, dichromatic, or—as in the owl monkeys and greater galagos—monochromatic.
Deception in animals scraggly, bumpy texture of a rock, among other disguises. A few species, such as the mimic octopus, have another defence mechanism. They can combine their highly flexible bodies with their colour-changing ability to accurately mimic other, more dangerous animals, such as lionfish, sea snakes, and eels. A well-researched form of deception is feigning death, often referred to by non-specialists as "playing dead" or "playing possum", although specialists use the terms "tonic immobility" or "thanatosis". A wide range of animals, e.g. lizards, birds, rodents, and sharks, behave as if dead as an anti-predator adaptation, as predators usually take only live prey.