An animal’s habitat can cause it problems when it comes to getting about. Nature, though, has risen to the challenge with a breathtaking variety of modifications and techniques – some of which are decidedly bizarre. By Mike Unwin
Strictly come dancing
Shovel-snouted lizards are found only in the sand dunes of the Namib, where the surface temperature can exceed 50ºC. Like all reptiles, this lizard absorbs heat from its surroundings. It sleeps at night beneath the sand, then emerges during the day when the sun has warmed the surface, in its quest for the insects and windblown seeds that form its diet. When the going gets too hot there are various ways to escape: it can corkscrew head-first down into the cooler sand below, or race up to the crest of a dune to catch a breeze. Or it can dance. The thermoregulatory dance of the shovel-snouted lizard is a comical business. It lifts its body from the sand on stiff legs, as though stilt walking, then raises its diagonally opposite front and hind legs – alternating in pairs – while holding its tail aloft. In this way no part of the body remains in contact with the surface for too long.
The wheel deal
Here’s the only animal on the planet to turn itself into a wheel and cartwheel downhill. Belonging to the large Sparassidae group of huntsman spiders, the Carparachne aureoflava lies in wait for its prey in a long, silk-line burrow, which it has dug 40-50cm into the face of a sand dune.
But when a Pompilid wasp arrives on the scene this spider needs to take elusive action. The wasp paralyses spiders with its sting and lays its egg inside their body – a hideous fate indeed, as the wasp larva hatches within the still-living spider and consumes it from the inside out.
An exposed spider is highly vulnerable. If it runs the speedy wasp will quickly overhaul it. So it rolls up its legs and tilts its body on its side to form a wheel shape, then simply trundles off down the dune slope. It can cover a considerable distance in this way, whizzing along at an amazing 20 rotations per second – fast enough, with luck, to throw the wasp off its scent.
Walking on water is not as hard as you might imagine – as long as you have the right feet for the job. And the African jacana has a pair of whoppers.
This moorhen-sized bird is a common sight around the wetlands across sub-Saharan Africa, picking its way across floating vegetation on its extraordinarily long toes. These outsized digits spread out to distribute its weight, allowing it to move with ease across the water’s surface.
Occasional sinking is not a problem: jacanas swim well, and may plunge below the surface to escape a predator.
Food comprises aquatic invertebrates such as insects, snails and tiny crabs. Jacanas forage over the water’s surface and around the edge. Often they will lift the edge of a lily to snap up any goodies underneath, with quick stabs of their sharp, bright-blue bill.
Catching a kip while upright does not generally cause a stir. But in the upside-down world of bats it is a positively outrageous stunt – and two species in Madagascar have evolved a unique means of pulling it off. The clue is in the name: sucker-footed bats.
The suckers in question are tiny horseshoe-shaped pads located on the bats’ wrists and ankles. Onto these the bat secretes an adhesive liquid from special glands, creating a bond strong enough to suspend its entire body from a smooth vertical surface – specifically that of the palm leaves in which it roosts.
They feed primarily on small moths, which they capture at night by echolocation, using those big ears to pick up the returning signals from their unusually long calls. Their long wings allow a particularly agile flight in order to pursue this elusive diet, and their tail, which is longer than that of most bats, protrudes from the flight membrane to help support the bat in its upright roost.