Animal Adaptations: How Wildlife Copes with Heat, Cold, Diet and Predators

An animal’s body is a record of how it lives. The long legs of a cheetah, the huge ears of a fennec fox, the flat teeth of a zebra and the hollow hairs of a polar bear all tell a story about environment, diet and danger. Reading these adaptations helps wildlife biologists predict how animals behave, what they need and how they may respond to change.

What you will learn

How animals control body temperature and water
How teeth, guts and senses reflect diet
How animals avoid predators and catch prey
How to “read” an animal’s lifestyle from its body

Temperature control

Animals fall into two broad groups:

Endotherms (mammals and birds) generate heat internally and keep a fairly constant body temperature. This allows activity in cold conditions but requires a lot of food.
Ectotherms (most reptiles, amphibians, fish and invertebrates) rely mainly on external heat, basking to warm up and seeking shade to cool down. They need far less food; a large snake may eat only a few meals a year.

Coping with cold

Insulation: thick fur (musk ox, snow leopard), blubber (seals, whales) and dense feathers (penguins).
Body shape: animals in cold climates tend to be larger (Bergmann’s rule) with shorter extremities (Allen’s rule), reducing heat loss.
Countercurrent heat exchange: warm and cold blood vessels run side by side in the legs of wading birds and the flippers of penguins.
Huddling and shelters: emperor penguins huddle; many small mammals live under the snow in insulated tunnels.
Hibernation and torpor: bears, marmots and bats lower their body temperature and metabolism to survive winter food shortages. Hummingbirds enter nightly torpor.

Coping with heat and drought

Heat-shedding ears and limbs: elephants flap their ears; fennec foxes and jackrabbits have large, blood-rich ears.
Tolerating high body temperature: camels and oryx let their body temperature rise during the day, saving water that would otherwise be used for sweating.
Water saving: kangaroo rats produce very concentrated urine and can survive on water made from digesting seeds; camels produce dry dung.
Behaviour: many desert animals are nocturnal or rest in burrows through the heat of the day.

Diet: teeth, guts and senses

Teeth are one of the best clues to diet:

Diet	Teeth	Gut	Examples
Carnivore	Sharp canines, blade-like carnassials for slicing	Short, simple	Lion, wolf, otter
Grazing herbivore	Broad, ridged grinding molars, often ever-growing	Long, with fermentation chambers	Zebra, wildebeest, capybara
Browsing herbivore	Lower-crowned molars for leaves	Long, complex	Giraffe, kudu, black rhino
Omnivore	Mixed teeth	Intermediate	Bears, pigs, many primates
Insectivore	Small, pointed teeth, or none	Short	Shrews, bats, anteaters (no teeth)

Many herbivores cannot digest plant cellulose themselves and rely on microbes. Ruminants such as cattle, deer and antelope ferment food in a four-chambered stomach and chew the cud. Hindgut fermenters such as horses, zebras, rhinos and elephants ferment food in an enlarged caecum and colon; they digest less efficiently but can process more low-quality food quickly.

Senses also match diet and lifestyle. Owls have forward-facing eyes and asymmetrical ear openings to pinpoint prey in darkness. Bats and dolphins use echolocation. Sharks and platypuses detect electric fields. Snakes such as pit vipers and pythons sense infrared heat from warm-blooded prey.

Defence and hunting

Avoiding predators

Camouflage: matching the background (snow leopard), disruptive patterns that break up the outline (zebra, giraffe) and countershading (darker on top, lighter below, as in many fish and antelope).
Warning colours: bright colours advertise toxins, as in poison dart frogs and many caterpillars.
Mimicry: harmless species copying dangerous ones.
Armour and spines: pangolins, armadillos, porcupines and tortoises.
Vigilance and groups: herds, flocks and schools increase the chance of spotting predators.
Speed and agility: gazelles, hares and many birds.

Catching prey

Predators show a range of strategies: ambush (crocodiles, leopards), high-speed pursuit (cheetahs, peregrine falcons), endurance hunting (wolves, African wild dogs), cooperative hunting (lions, orcas), traps (spider webs) and venom (snakes, scorpions, cone snails).

Reading an animal’s lifestyle

Put the clues together and you can make good predictions about an unfamiliar animal:

Eyes on the front of the head suggest a predator that judges distance; eyes on the sides suggest prey that watches for danger.
Long legs and hard hooves suggest open habitats and running; short legs and a rounded body suggest dense cover.
Webbed feet and nostrils on top of the head suggest a semi-aquatic life (hippos, capybaras, crocodiles).
Large ears in a desert animal suggest heat loss; small ears in a cold-climate animal suggest heat retention.

Case study: the Arctic fox and the fennec fox

The Arctic fox and the fennec fox are close relatives living at opposite extremes. The Arctic fox has small ears, a short muzzle, thick fur that turns white in winter and fur on the soles of its feet, and can survive temperatures below −40 °C. The fennec fox of the Sahara has the largest ears relative to body size of any canid, used to shed heat and to hear prey underground, pale sandy fur and furry soles that protect it from hot sand. The two show how quickly evolution shapes bodies to climate.

Try it yourself

Look at a photograph of an animal you do not know. From its eyes, ears, teeth, legs and colour, predict its diet, habitat and main predators. Then look up the species and check how close you were.

Key terms

Endotherm and ectotherm: animals that generate their own heat and those that rely on external heat.
Torpor and hibernation: short-term and seasonal reductions in metabolism.
Ruminant: a herbivore with a multi-chambered stomach that chews the cud.
Countershading: darker upper and lighter lower body surfaces that reduce visibility.
Countercurrent exchange: heat transfer between vessels running in opposite directions.

Anatomy, Physiology and Adaptations