animal behaviour
edyong | May 18, 2009For the longest time, people believed that the world's largest lizard, the Komodo dragon, killed its prey with a dirty mouth. Strands of rotting flesh trapped in its teeth harbour thriving colonies of bacteria and when the dragon bites an animal, these microbes flood into the wound and eventually cause blood poisoning.
But that theory was contested in 2005 when Bryan Fry from the University of Melbourne discovered that a close relative, the lace monitor, has venom glands in its mouth. The discovery made Fry suspect that Komodo dragons also poison their prey and he has just confirmed that in…
edyong | May 14, 2009Many plants depend so heavily on visits from bees that they go to great lengths to attract them, using brightly coloured flowers baited with sweet nectar. But some of their tricks are much subtler and are designed not to attract six-legged visitors, but to make their stay more convenient.
The majority of flowering plants have evolved special conical cells that line the surface of their petals and are found nowhere else. These cells provide the flower with a rougher texture that is indistinguishable to human fingers, but that provide just enough purchase for the claws of landing insects.…
edyong | May 12, 2009In Mexico's Cueva del Azufre (the Sulphur Caves), a small fish called the shortfin molly (Poecilia mexicana) is on the way to becoming two separate species. Those that live in the dark interior of the caves are very different to their relatives that swim in the bright, surface waters. They have lighter colours and live more solitary lives. Their eyes are smaller, less sensitive and have lower levels of light-sensitive pigment. Instead, they rely instead on a hypersensitive pressure detector - the lateral line - to sense disturbances in the water.
Their differences aren't just skin deep…
edyong | May 8, 2009The success of termites Âand other social insects hinges on their complex social systems, where workers sacrifice the ability to raise their own young in order to serve the colony and its queen - the only individual who reproduces. But this social order can be thrown into chaos by knocking out a single gene, and one that originally had a role in that other characteristic termite ability - eating wood.
Judith Korb from the University of Osnabrueck in Germany found that the queen termite relies on a gene called Neofem2 to rule over her subjects. Korb worked with the termite Cryptotermes…
edyong | May 6, 2009We recognise dead people by the absence of signals that indicate life - movement, responsiveness, pulses, brain activity, and so on. The Argentine ant does the same, but its signal is a chemical one. Throughout its life, an ant uses chemicals in its skin to automatically send out a message to its nest-mates, saying "I'm alive. Don't throw me out." When it dies, these "chemicals of life" fade away, and their bodies are evicted.
Social insects like ants and honeybees are fastidious about their colony's tidiness. If any individuals die, they're quickly removed and thrown away in one of the…
neurophilosophy | May 4, 2009Human cultural traits such as language, dress, religion and values are generally said to be passed from one generation to the next by social learning. And in animal species which have language, the same is true; male song birds, for example, learn the songs with which they serenade potential mates from older male relatives.
A new study, published online in the journal Nature, shows that the songs of isolated zebra finches evolve over multiple generations to resemble those of birds in natural colonies. These findings show that song learning in birds is not purely the product of nurture, but…
edyong | May 4, 2009Most of us start to tire after about half a day without any sleep. Staying awake for five in a row would be extremely difficult and even if you could manage it, you'd be a physical and mental wreck by the end. But not all animals suffer from the same problem. A dolphin can stay awake and alert for at least 5 days straight, chaining together all-nighters without any noticeable health problems or loss of mental agility.
The two halves of a dolphin's brain can sleep in shifts, "shutting down" one at a time so that the animal is always half-awake. They can truly sleep with one eye open, an…
edyong | May 2, 2009
Impressionists are a mainstay of British comedy, with the likes of Rory Bremner and Alistair MacGowan uncannily mimicking the voices of celebrities and politicians. Now, biologists have found that tiger moths impersonate each other too, and they do so to avoid the jaws of bats.
Some creatures like starlings and lyrebirds are accomplished impersonators but until now, we only had anecdotal evidence that animals mimic each others' sounds for defence. Some harmless droneflies may sound like stinging honeybees, while burrowing owls deter predators from their burrows by mimicking the…
edyong | April 30, 2009Snowball, the sulphur-crested cockatoo, is an internet superstar. He's known for his penchant for grooving to music, notably Everybody by the Backstreet Boys. As the music plays, Snowball bobs his head and taps his feet in perfect time with it. If it speeds up or slows down, his rhythm does too. He is one of two parrots that are leading a dance dance revolution, by showing that the human behaviour of moving in time to music (even really, really bad music) is one that's shared by other animals.
People who've attended parties at scientific events may question the ability of humans to move to a…
edyong | April 28, 2009The courtship rituals of the spider Harpactea sadistica start innocently enough, with a dance and a hug. The male spider taps the female gently with his front legs and embraces her. But from that point onwards, things for the female go rapidly downhill. The male bites her and she becomes passive, allowing him to manoeuvre her into position. Like all spiders, his genitals are found next to his head, on a pair of appendages called the pedipalps. But unusually, his penis ends in a needle-sharp tip called an embolus.
The embolus sits at the end of a loop called the conductor. The male hooks one…
edyong | April 27, 2009For many animals, living with others has obvious benefits. Social animals can hunt in packs, gain safety in numbers or even learn from each other. In some cases, they can even solve problems more quickly as a group than as individuals. That's even true for the humble house sparrow - Andras Liker and Veronika Bokony from the University of Pannonia, Hungary, found that groups of 6 sparrows are much faster at opening a tricky bird feeder than pairs of birds.
After ruling out several possible explanations, the duo put the speedy work of the bigger flock down to their greater odds of including…
edyong | April 24, 2009In the forests of Singapore lives a spider that must be an arachnophobe's worst nightmare. Most species are solitary hunters subdue their prey with venomous fangs, sticky silken webs or a combination of the two. But Scytodes uses a third trick - it spits a sticky, venomous fluid from its fangs that both traps its victims and poisons them (see video of related species). And it does this in packs - after hatching, spiderlings spend their early lives on their home web and they spit at, bite and devour prey en masse.
There are actually about 200 species of spitting spiders belonging to the genus…
edyong | April 21, 2009For long journeys, the shell of a snail hardly seems like the ideal public transport. That is, of course, unless you're an even smaller snail...
Yasunori Kano from the University of Miyazaki has found that the babies of Neritina asperulata, a tiny snail just 3 millimetres across, hitchhike on the back of a larger species Neritina pulligera. This living bus is about 2 centimetres long, and dwarfs its passengers by more than seven times.
The hitchhiking snail is a special sort of parasite, and one that Kano thinks has never been described before. They don't use their hosts as a snack, a home…
edyong | April 20, 2009
Studying the way an animal moves by looking at its ears might seem like a poorly thought-out strategy. After all, short of watching it directly, most biologists would choose to look at more obvious traits like tracks, or limb bones.
But while an animal's limbs may drive it forward, its inner ear makes sure that it doesn't immediately fall over. By controlling balance, it plays a key role in movement, and its relative size can tell us about how agile an animal is.
When we walk, the image that forms on our retinas changes quite considerably. But no matter how fast or erratically we move,…
edyong | April 10, 2009We get a lot of information from watching other people. We read reviews, we follow links to recommended websites and we listen when our friends vouch for strangers. The opinions of strangers may even be a better guide to the things that make us happy than our own predictions. But humans aren't the only species to make decisions based on information gleaned from our peers - even animals as supposedly simple as flies can do the same.
Frederic Mery from LEGS (the Laboratory of Evolution, Genomes and Speciation) studied the fly Drosophila melanogaster and found that females have a tendency to…
edyong | April 8, 2009Many men think of little else besides sex and meat, but male chimpanzees will sometimes exchange one for the other. Chimps are mostly vegetarian but they will occasionally supplement their diet by hunting other animals, especially monkeys. Males do most of the hunting, but they don't eat their spoils alone - often, they will share the fresh meat with females, even those who are unrelated to them. Some scientists have suggested that this apparently selfless act is a trade - the males are giving up their nutritious catch in exchange for sex.
Cristina Gomes and Christophe Boesch from the Max…
edyong | April 5, 2009
For humans, our culture is a massive part of our identity, from the way we dress, speak and cook, to the social norms that govern how we interact with our peers. Our culture stems from our ability to pick up new behaviours through imitation, and we are so innately good at this that we often take it for granted.
We now know that chimpanzees have a similar ability, and like us, different groups have their own distinct cultures and traditions.
Now, Andrew Whiten from the University of St Andrews has published the first evidence that groups of chimpanzees can pick up new traditions from each…
edyong | April 3, 2009
Say the word 'statistician' and most people might think of an intelligent but reclusive person, probably working in a darkened room and almost certainly wearing glasses. But a new study shows that a monkey in front of a monitor can make a reasonably good statistician too.
Tianming Yang and Michael Shadlen from the University of Washington found that rhesus macaques can perform simple statistical calculations, and even watched their neurons doing it. Psychologists often train animals to learn simple tasks, where the right choice earns them a reward and the wrong one leaves them empty-…
edyong | April 1, 2009Humans aren't the only species that have had to deal with the issue of slavery. Some species of ants also abduct the young of others, forcing them into labouring for their new masters. These slave-making ants, like Protomagnathus americanus conduct violent raids on the nests of other species, killing all the adults and larva-napping the brood.
When these youngsters mature, they take on the odour of their abductors and become the servants of the enslaving queen. They take over the jobs of maintaining the colony and caring for its larvae even though they are from another species; they even…
edyong | March 28, 2009
Animals have distinct personalities and temperaments, but why would evolution favour these over more flexible and adaptible mindsets? New game theory models show that animal personalities are a natural progression from the choices they make over how to live and reproduce.
Any pet owner, wildlife photographer or zookeeper will tell you that animals have distinct personalities. Some are aggressive, others are docile; some are bold, others are timid.
In some circles, ascribing personalities to animals is still a cardinal sin of biology and warrants being branded with a scarlet A (for…