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There’s an old joke about a cheeky pupil handing their art teacher a blank piece of white paper at the end of a lesson.

When asked what it is, the pupil explains, matter-of-factly, that it’s a polar bear in a snowdrift.

While that’s unlikely to score them top marks, it does highlight our awareness of the animal world’s ability to blend in with its surroundings.

And sometimes, as ����tv Bitesize shows, that ability can be breathtaking.

The secret of the Sumatran tiger

Dan Simmonds is head keeper at London Zoo, which is home to more than 14,000 animals from across the world. He talked Bitesize through the camouflage techniques used by four of the creatures there, beginning with the mysterious Sumatran tiger.

“This is one of the most endangered big cats you’ll ever see and, as the name would suggest, they come from the mangrove swamps of Sumatra,” he said.

And it’s the swamp setting which has naturalists both fascinated and baffled. The murky colours we associate with those surroundings are at odds with the striking oranges and blacks in the tiger’s stripes. That doesn’t stop the big cats from being absolute masters at camouflage - and, as Dan explained, nobody knows exactly how they do it.

He continued: “What are the colours of a mangrove swamp? You’d probably, out of all the colours you could come up with, you wouldn’t come up with orange… but the incredible thing is, whether they’re at the zoo in a much greener environment, against more British-style foliage or basic grass or whether they’re in the mangroves of Sumatran Indonesia, they disappear. It’s absolutely incredible.

“That’s just how they’ve managed to evolve, they’re an ambush predator so they rely on being able to camouflage themselves, otherwise they would literally starve to death.”

Sumatran tigers are also apex predators, meaning they are not naturally preyed upon by other animals for food. Their different stripes make each individual tiger at the zoo identifiable to the conservationists there, but not any easier to find when the cats choose to hide - a mystery Dan attributes to nature, “always being able to surprise us and stay one step ahead of us.”

He added: “We challenge visitors to spot a tiger. We’ll say, ‘look, it’s there’ - and they can’t see it.”

Why a penguin’s tuxedo is more than just a suit

A colony of penguins waddling in unison can be one of nature’s more loveable sights. Their bodies are covered in tightly packed feathers, mainly black, with white fronts. When Dan and his colleagues are introducing the colony of 70-plus Humboldt penguins at London Zoo to visitors, they often refer to the birds’ ‘little tuxedos’.

Those ‘suits’ are not just for looking natty in the water, either. They provide a surprising form of camouflage too. Dan said: “The white belly and the black back are counter-shading. If you’re swimming along as a penguin and your white bits are facing downward, it’s camouflage against the sky from a predator looking upwards.”

But that’s not all. Dan continued: “If you’ve got your back facing up to the sky against the deep dark ocean, you’re going to blend in there, so it’s counter-shading - a safety tuxedo. It’s a really nice thing that penguins have. We try not to be emotive, but sometimes you looks at the penguins and think that they’re vulnerable - but they’re not. Nature and evolution protects them through camouflaging.“

The crocodile lurking in the murky depths

Another apex predator on the list is the Philippine crocodile. Unlike the Sumatran tiger, the "muddy-ish, brown-ish" colour of the reptile’s skin that Dan describes matches well with its marsh-like surroundings. At London Zoo, the team includes an enclosure design officer, who works to replicate the animal’s surroundings as close to their natural habitat as possible in the middle of a busy city.

He said: “When people come to the zoo, it’s interesting to watch them. In the reptile house, right at the front of the viewing glass, the crocodiles disappear. They have an ability to blend in due to the colour and texture of their skin. If we tried to do it as humans we probably couldn’t do it, but nature does it so well.”

This seemingly effortless blending makes it easier for a Philippine crocodile to ambush its prey. “This is one you’ll normally see on social media,” Dan explained. “A creature is drinking from the water and a crocodile will launch itself at them and the animal has been completely oblivious, [the crocodile has] been invisible on the shoreline.”

Why is that stick moving?

The tirachoidea is one of the stick insects housed at London Zoo. Native to South East Asia, it could be even more difficult to spot than a Philippine crocodile, even if it isn’t planning to pounce on an unsuspecting meal.

The insect looks remarkably like a twig but doesn’t just leave it at the cosmetic level - the tirachoidea behaves like one as well.

While resting on a twig, it moves as though it is swaying in the wind, mimicking the behaviour of the tree surrounding it. There’s variety within the species as well. Dan said: “The male tirachoidea are green with orange stripes, while the wingless females are green with brown dots.

“It’s also known as Cantor’s stick insect and threats that it faces include primates, bats and reptiles.”

It’s also a very large insect. For the zoo’s annual weigh-in and measurements procedure, a tirachoidea has to perch on a particularly long ruler.

This article was published in October 2023.