Adrenaline A chemical released into the bloodstream when an animal senses danger. It makes the heart beat faster, sending more blood around the body, so the muscles can work harder.

Alpha animal An individual that leads and influences the rest of its group. The alpha has the best food and the first pick of mates. He or she is often the largest, strongest or oldest member of the group. In some species, such as baboons, the alphas all descend from one “royal” family.

Ambush A surprise attack. In an ambush, a predator hides until its prey approaches, when it suddenly darts out. Ambushes use less energy than long chases.

Apparent death A type of self-defence where an animal feigns death if threatened. This deters those predators that prefer to make their own kill. Many snakes feign death. The Virginia opossum also uses apparent death, also called “playing possum”.

Arboreal locomotion The movement of animals in trees. Many arboreal mammals have long limbs to reach across gaps and sharp claws to grip bark. Frogs and lizards cling to trees with their sticky finger pads, and snakes use their muscular bodies to climb branches.

Armour A hard body covering that helps protect animals. Armour may take the form of a hard shell, as in tortoises, or overlapping scales, as in armadillos. Some reptiles also have armour-like, scaly skin.

Autotomy The action of deliberately losing a body part, used by some animals to distract predators while they escape. For example, some lizards can shed the tip of their tail, which continues to twitch as the lizard runs away. Insects and spiders shed their limbs in a similar way.

Bipedal An animal that moves on two legs. Apes and large birds put one leg in front of the other. Others, such as kangaroos, hop on two legs. A few species, such as the basilisk lizard, may run on two legs in short bursts, to escape predators.

Birdsong The musical calls made by some species of bird in order to mark out their territory or attract a mate. Birds also make shorter calls to alert others to danger.

Brachiation A type of arboreal movement used by monkeys to swing by their arms from branch to branch.

Brood parasite An animal that tricks other species into raising its young. For example, cuckoos lay their eggs in the nests of other birds. The young hatch and push the eggs around them out of the nest, securing all of the nestlings’ food for themselves.

Camouflage The means by which animals escape the notice of predators or prey, using their colours, patterns or body shape to blend in with their surroundings.

Chemical defence A form of self-defence where an animal sprays toxic liquids over its attacker. This is common in insects and in some mammals, such as skunks.

Circadian rhythm A 24-hour body clock that guides the behaviour of most organisms, affecting patterns such as sleep and digestion. Circadian rhythms continue regardless of light and dark.

Colony A group of one kind of animal living together. Some animals, such as ants, form permanent colonies, co-operating to feed and breed as part of a unit. Other animals gather only to breed.

Commensalism A relationship between two living things in which one benefits and the other is unaffected. For example, jackals sometimes follow tigers, feeding on the remains of their kills.

Competition The struggle for survival within or between species as they compete for limited food, water or territory. Competition allows natural selection to occur, with animals better suited to their habitat and lifestyle being more likely to survive.

Countershading A type of camouflage used by many fish. A dark back enables the fish to blend in with the depths when seen from above; a pale underside enables it to merge with the light surface waters when seen from below.

Courtship Behaviour used to attract a mate. Some animals, especially birds, have elaborate courtship behaviour, often involving “dances”. It helps the animals to select partners that are sexually mature, strong, fit and healthy.

Diurnal Active during the day and inactive during the night.

Echolocation Echolocation is the method by which some animals, such as bats and whales, sometimes navigate and find their prey. They emit high-pitched sounds and listen to the echoes to build up a picture of their surroundings.

Ethology The study of animal behaviour.

Eusocial animals Animals that live in tightly organized units and depend on one another for survival. Different groups within the unit are responsible for certain tasks such as finding food, raising young or defending the group. Most eusocial animals are insects, such as ants and bees.

Fixed action pattern Instinctive animal behaviour as a result of an animal’s genes. For example, it is thought that some bird courtship displays are fixed action patterns.

Hibernation The process whereby some mammals spend winter in a state of reduced body activity. Body temperature drops significantly, enabling the animal to conserve energy.

Imitation Behaviour where an animal copies another animal’s actions. In the 1980s, researchers observed one Japanese macaque (a monkey) washing her food in the river, rather than brushing it off like other macaques. This useful behaviour was soon imitated by those around her.

Imprinting A form of learning where some newborn birds or mammals recognize and follow the first moving thing they see, usually a parent.

Irruption Any migration that occurs at random intervals. Irruptions may involve some, many or all of a population. For example, lemmings are known for their irruptive migrations, which occur if there is a shortage of food, or if they become overcrowded.

Magnetic navigation Some animals can detect the Earth’s magnetic field and use it as a guide when they migrate. Bats, sea turtles and birds use magnetic navigation. Scientists think they can do this because their brains contain tiny particles of a magnetic mineral called magnetite.

Migration The movement of an animal or a group of animals from one place to another. This usually takes place once a year, in a certain season. Animals may migrate to find food or to reach conditions more suitable for breeding. Migrations take place over land, by air and by water. Birds migrate the farthest, because flight enables them to cover long distances. An animal that migrates is called a migrant.

Mimicry A similarity between two species that protects one or both of them. Some animals mimic other, more dangerous species, in order to scare off predators. For example, some harmless flies have similar markings to bees and wasps.

Mobbing behaviour An attack launched by a group of animals in order to drive away an attacker. Mobbing is common in animals such as nesting birds, whose young are at risk.

Nest A structure built by an animal in which it cares for its eggs or young.

Nocturnal Active during the night and inactive during the day. In hot areas, animals may be nocturnal to avoid the heat of the day. Some animals, such as bats, hunt at night to avoid competition with others—in the case of bats, birds.

Pack-hunter A predator that hunts as part of a group. Pack-hunters increase their chance of success by surrounding prey, or working to bring down large prey.

Paralysing The use of venom, by biting or stinging, to capture prey. This results in the victim not being killed, but being unable to move. Some spiders, scorpions and centipedes paralyse their prey before feeding on it later. Wasps paralyse prey in order to store it for feeding to their larvae.

Parasite A living thing that depends on another living thing (a host) for needs such as food and shelter.

Parasitoid A parasite that kills its host. The young of some insects are parasitoid.

Predator An animal that kills and eats other animals.

Prehensile Capable of grasping. Some animals, such as monkeys, have a prehensile tail, used as an extra limb when climbing through the trees.

Prey An animal that is hunted and eaten by other animals.

Pronking A sudden, stiff-legged leap into the air, used by some herd animals, especially gazelles, as they run from predators. It is thought to be a signal to the pursuing predator that the individual is fit and the predator would do better to chase another animal in the herd.

Quadrupedal An animal that moves on four legs. Most land mammals are quadrupedal.

Sessile An animal that is not able to move about as an adult. For example, mussels are stuck to seashore rocks, but were mobile during their young stages.

Social animals Animals that live in groups. They may share tasks such as finding food or looking out for predators. A few kinds of animals, such as wolves and lions, work together in packs to hunt.

Spines Sharp, needle-like protrusions on the body of animals such as hedgehogs, porcupines and porcupine fish. When threatened, a porcupine curls into a ball or backs into its attacker, leaving spines embedded in its attacker’s skin.

Startle display A sudden action intended to intimidate or startle an attacker. Some animals flash bright colours or patterns to startle predators. Other animals suddenly puff up to make themselves appear larger, or leap out to scare their predator.

Sting A short, sharp organ belonging to some animals, such as bees, ants and scorpions. Stings inject venom into other animals, in order to paralyse or kill prey, or harm attackers.

Symbiosis A relationship between members of two species in which one or both benefit. An example of symbiosis is clownfish, which live among the vemomous tentacles of sea anemones, which do not harm the fish but kill its enemies. The anemone feeds on plankton drawn in by currents created by the clownfish.

Territory An area that an animal or group of animals defends against others of its kind. This removes competition for food and protects young from potential danger. Animals mark their territory by leaving their scent around its borders, or by making loud calls.

Venom A poisonous substance found in the bodies of some animals, including species of snake, spider, scorpion and fish. Venom can be used for killing prey or defence, and is usually injected with a sharp sting or bite. Venomous predators may give warning that they are about to strike.

Warning colours Bright colours and markings that warn that an animal tastes bad or is poisonous to eat. Certain fish, beetles, caterpillars, moths and butterflies have horrible-tasting or poisonous flesh. Predators soon learn to avoid them because they recognize their colours. Warning colours may also signal that an animal is venomous. For example, several venomous snakes are brightly coloured.

Consultant: Chris Jarvis