Monday, 22 July 2013

Animal Camouflage - Now You See Me... Now You Don't

Recently on Cage and Aviary Bird Magazine, I subbed an article from a franchise called Misadventures of a Birdkeeper. (Subbing is ensuring the article is grammatically correct, as well as making sure it is written in a clear, concise way). 

This franchise is all about contributor Bill Naylor's life working in various zoos, bird gardens and museums in the UK and overseas. In this feature he mentioned the camouflage techniques of the tawny frogmouth.

Native to Australia, they live in open forests and woodlands. They are often mistaken for owls because of their appearance and nocturnal habits, however they are more closely related to nightjars. These birds mainly eat large night-active insects and spiders and a male and female will pair for life. 

However, what makes these birds so fascinating is the way they disguise themselves! During the day the tawny frogmouth will roost in bare, sheltered trees, stumps or just on sheltered ground. At the slightest hint of a potential threat or even a disturbance, they will freeze, pack in their feathers and close their eyes to resemble slits. After this, they will look like a broken branch. Only if they are then pushed, will they reveal themselves with a frightening snapping of their yellow bills. 

This act of camouflage is the way an animal can blend in with its surroundings, and this is due either to its body's shape or the colour of its coat/skin to help it match its habitat. It's used for two reasons: to hunt or to hide from predators. 

The arctic fox is a predator that needs to be able to creep up on its prey. The natural hue of its coat acts as an effective winter camouflage because they blend into the snow and ice of the arctic. When food is scarce during winter, they will follow the area's main predator - the polar bear - to eat scraps from their kills. This makes their disappearing act more vital than ever. 

When the seasons change, the fox's coat does too and so in summer it adopts a brown or grey appearance. This helps it to blend in with the rocks and plants. An extremely hardy animal, the arctic fox can survive in temperatures that get as low as -50⁰C. It has furry soles, short ears and a short muzzle, which all help in a cold climate. They live in burrows, and when faced with a blizzard, will tunnel into the snow to create shelter. 

A master of disguise that everyone has heard of is the chameleon. These colourful creatures have transparent skin and special cells that enables them to change their skin colour. It can switch from one colour to another in under 15 minutes, allowing it to escape from any predators. Interestingly, this colour change is involuntary and is caused by light, temperature and reactions such as anger or fear. This change is not related to the colour of any plant that the chameleon is on or near. 

There are about 90 species of chameleon currently known and these are native to Africa, Spain, Madagascar, India and Sri Lanka. Its feet are adapted for grasping hold of branches and other foliage, as each foot has five toes arranged in pincher-like sections of two and three. A chameleon's eyes can also rotate, both together and independently and its tongue is almost as long as its body. 

Another way some animals camouflage is by countershading. This double disguise makes it difficult for  predators or prey to see them coming. 

Sharks use countershading effectively when hunting because they has a light stomach and dark back. Therefore, when sneaking up on a shoal of fish, a shark can approach from either above or below, because its dark and light colouring breaks up its shape, making it harder to be noticed. 

There are an estimated 375 species of shark and they have been around for nearly 400 million years, making them older than dinosaurs! Sharks do not have any bones because its skeleton is made up of cartilage. This gives it more flexibility in water and helps it to stay afloat. Amazingly, sharks do not have scales and actually have teeth-like structures called denticles that cover their body to help protect it. These make the shark feel like sandpaper. 

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