animal behaviour
edyong | May 13, 2008
Three-toed sloths have a reputation for being some of the sleepiest of all animals, largely due to a single study, which found that captive sloths snooze for 16 hours a day. That certainly seems like a sweet deal to me, but it seems that the sloth's somnolent reputation has been exaggerated.
A new study - the first ever to record brain activity in a wild sleeping animal - reveals that wild sloths are far less lethargic than their captive cousins. In their natural habitat, three-toed sloths sleep for only 9.6 hours a day, not much more than an average first-year university student.
Wild…
edyong | May 9, 2008
This week's New Scientist includes a short piece from me about conformist rats.
Until now, only humans and chimps were known to succumb to peer pressure, to the extent that we often ignore our own experiences based on the preferences of others. But a new study in brown rats shows that these rodents are similarly prone to following the Joneses. They can even be persuaded to choose a piece of food that they know makes them sick if they smell it on the breath of a 'demonstrator' rat.
Bennett Galef and Elaine Whiskin at McMaster University in Hamilton, Ontaria, Canada, trained rats to avoid…
edyong | May 8, 2008
A tenth of the planet's population occasionally suffers through devastating famines because small insects fear being bitten in the bum. That's the astonishing message from a new study of one of mankind's greatest pests - the desert locust.
Swarms can stretch for several hundred square kilometres and each of these harbours up to 80 million hungry sets of mandibles that eat their own body weight in food every day. These plagues are unpredictable but they only form when locust populations reach some sort of critical mass. Desert locusts are two insects for the price of one; at a crowded…
edyong | May 6, 2008Cuckoos are some of nature's most familiar conmen. Several species of this large family are murderous slackers, who shun their own parental responsibilities by deceiving other birds into caring for their chicks. In the process, they destroy the eggs of the unwitting adopted family to ensure that their own chick gets undivided attention. But this is not the only way that cuckoos fool other birds - they also mimic hawks.
The resemblance between cuckoos and hawks (particularly sparrowhawks) has been noted for millennia. Both birds have long bodies, wings and tails and their paler, striped…
edyong | May 1, 2008
Ultraviolet (UV) radiation lies beyond the violet end of the rainbow. Our eyes aren't equipped to see it and its presence only becomes visually apparent when enough of it hits our skin and causes a painful, red patch - a sunburn. But not all animals have eyes that are so ill-equipped. The females of the jumping spider Phintella vittata not only see UV light, they also find it sexy.
UV light may be invisible to us but many animals can see it and use it to communicate. Sometimes, this is deliberate, as in the case of blue tits using UV patches to seduce females. It can also be…
neurophilosophy | April 2, 2008It now seems clear that we have grossly underestimated the cognitive abilities of other animals. In recent years, research has shown, for example, that African cichlids use simple logic to infer their social status, and that rodents can think abstractly and learn to use tools.
Birds also display quite remarkable intelligence: the ability of crows to make and use tools is at least as sophisticated, if not more so, than that of chimpanzees. (See the film clips in my post on intelligence in birds.) And now, a study published last week in the Proceedings of the Royal Society B shows that rooks…
edyong | March 31, 2008You might not be that impressed to receive a clump of grass or branches on a first date, but a boto dolphin might think differently. A new study suggests that these Amazonian dolphins wave bits of flotsam to attract mates.
The boto is a freshwater river dolphin that swims through the currents of the Amazon and the Orinoco. They are elusive creatures that are difficult to study, so very little is known about their social lives.
Tony Martin from the University of St Andrews spent three years in the Amazonian Mamiraua reserve studying the behaviour of botos. During this time, he spotted over…
edyong | March 27, 2008My first ever feature article has just been published in this week's issue of New Scientist. It's about the ways in which songbirds are coping with the noisy din of cities. Low-frequency urban noises mask the calls that they use to attract mates, defend territories and compete with rivals. The race to adapt to this new soundscape has already seen some losers being forced out and some winners developing some intriguing strategies to cope with the clamour.
Robins have started to sing at night when it's quieter, while nightingales just belt out their tunes more loudly (breaking noise safety…
neurophilosophy | March 26, 2008Traditionally, the use of tools was believed to be restricted to humans and several other primate species, and, like language, was argued to be a major driving force behind the evolution of the human brain. However, this view is now being challenged. For example, in recent years it has become clear that birds have sophisticated tool-using abilities. Now, a group of researchers from the RIKEN Brain Science Institute in Japan have demonstrated for the first time that rats degus* can be trained to use simple tools.
The new study, by Okanoya et al, is published online today in the open access…
edyong | March 26, 2008Would you gamble on a safe bet for the promise of something more? Would you risk losing everything for the possibility of greater rewards? In psychological experiments, humans tend to play it safe when we stand to gain something - we're more likely to choose a certain reward over a larger but riskier one. Now, we're starting to understand how our two closest relatives deal with risk - bonobos, like us, tend to be risk-averse while chimpanzees usually play the odds.
Sarah Heilbronner from Harvard University studied the attitudes of five chimps and five bonobos to risky decisions. All the…
edyong | March 24, 2008Bdelloid rotifers are one of the strangest of all animals. Uniquely, these small, freshwater invertebrates reproduce entirely asexually and have avoided sex for some 80 million years. At any point of their life cycle, they can be completely dried out and live happily in a dormant state before being rehydrated again.
This last ability has allowed them to colonise a number of treacherous habitats such as freshwater pools and the surfaces of mosses and lichens, where water is plentiful but can easily evaporate away. The bdelloids (pronounced with a silent 'b') have evolved a suite of…
edyong | March 21, 2008Eagles may be famous for their vision, but the most incredible eyes of any animal belong to the mantis shrimp. Neither mantises nor shrimps, these small, pugilistic invertebrates are already renowned for their amazingly complex vision.
Now, a group of scientists have found that they use a visual system that's never been seen before in another animal, and it allows them to exchange secret messages.
Mantis shrimps are no stranger to world records. They are famous for their powerful forearms, which can throw the fastest punch on the planet. The arm can accelerate through water at up to 10,000…
edyong | March 17, 2008
Geckos are nature's champion climbers. With remarkable ease, they can scamper across ceilings and up smooth vertical surfaces, and they do so at speed. A vertically running gecko can cover 15 times the length of its body in a single second. So far, scientists have focused their attention on the gecko's amazingly adhesive feet but a new study demonstrates the importance of a neglected piece of their climbing gear - their tails. Geckos use their tails to stop themselves from falling, and to land safely if they do.
A gecko's foot is a marvel of biological engineering. Rather than relying on…
edyong | March 14, 2008Crocodiles and alligators are the epitome of stealth. They can wait motionlessly for prey on the surface of the water, dive to the bottom, or roll around the length of their bodies, all without creating a single ripple.
This sneaky manoeuvrability is all the more impressive for the fact that a crocodilian can pull it off without moving its legs or tail. It's particularly difficult because a waiting crocodilian has to move slowly and methodically, and must make do without the helpful forces of lift and drag that accompany faster movements.
Now, for the first time, we know how they do it. They…
edyong | March 13, 2008
Many animals have cunning ways of hiding from predators. But the larva of the sand dollar takes that to an extreme - it avoids being spotted by splitting itself into two identical clones.
Sand dollars are members of a group of animals called echinoderms, that include sea urchins and starfish. An adult sand dollar (Dendraster excentricus) is a flat, round disc that lives a sedate life on the sea floor. Its larva, also known as a pluteus, is very different, a small, six-armed creature that floats freely among the ocean's plankton.
A pluteus can't swim quickly, so there is no escape for one…
edyong | March 11, 2008
Some of us have enough trouble finding the food we want among the ordered aisles of a supermarket. Now imagine that the supermarket itself is in the middle of a vast, featureless wasteland and is constantly on the move, and you begin to appreciate the challenges faced by animals in the open ocean.
Thriving habitats like coral reefs may present the photogenic face of the sea, but most of the world's oceans are wide expanses of emptiness. In these aquatic deserts, all life faces the same challenge: how to find enough food. Now, a couple of interesting studies have shed new light on the…
edyong | March 10, 2008
The story of evolution is filled with antagonists, be they predators and prey, hosts and parasites, or males and females. These conflicts of interest provide the fuel for 'evolutionary arms races' - cycles of adaptation and counter-adaptation where any advantage gained by one side is rapidly neutralised by a counter-measure from the other. As the Red Queen of Lewis Carroll's Through the Looking Glass said to Alice, "It takes all the running you can do, to keep in the same place."
The Red Queen analogy paints a picture of natural foes, wielding perfectly balanced armaments and caught in a…
neurophilosophy | March 8, 2008
Sea cucumbers are marine invertebrates which live on the sea floor and feed on debris that drift down. When threatened, they can harden their skin within seconds, so that they are less likely to be devoured by the approaching predator.
This behaviour is made possible by the structure of the sea cucumber's skin, whose deeper layers contain a network of collagen nanofibres enveloped within a viscous and elastic matrix of connective tissue. The arrangement of the collagen can be transiently modified, in response to a protein secreted by nerve cells found in the skin, which alters the chemical…
edyong | March 4, 2008The transformation from caterpillar to butterfly or moth is one of the most beguiling in the animal world. Both larva and adult are just stages in the life of a single animal, but are nonetheless completely separated in appearance, habitat and behaviour. The imagery associated with such change is inescapably beautiful, and as entrancing to a poet as it is to a biologist.
According to popular belief, within the pupa, the caterpillar's body is completely overhauled, broken down into a form of soup and rebuilt into a winged adult. Richard Buckmister Fuller once said that "there is nothing in a…
neurophilosophy | December 28, 2007In this wonderful passage from King Solomon's Ring, Konrad Lorenz, who, together with Nikolaas Tinbergen and Karl von Frisch founded the science of ethology, describes some of the behaviours of his pet capuchin monkey Gloria:
She occupied a large, roomy cage in my study. When I was at home and able to look after her, she was allowed to run freely about the room. When I went out, I shut her in the cage, where she became exceedingly bored and exerted all her talents to escape as quickly as possible. One evening, when I returned home after a longer absence and turned the knob of the light switch…