Animal defences
edyong | February 9, 2010Mothers can teach their children much about the world, but some mothers can do it without ever meeting their young. Take the field cricket Gryllus pennsylvanicus. A female cricket isn't exactly a caring mother. Once she lays her eggs, she abandons them to their fate. But amazingly, she can also forewarn her young of the dangers they might face. If a pregnant female is exposed to a wolf spider, her experiences affect her unborn young. When they hatch, the baby crickets are more likely to freeze when they smell wolf spiders nearby.
If mothers sense a threat in their environment, there are…
edyong | January 28, 2010
When our lives are in danger, some humans go on the run, seeking refuge in other countries far away from the threats of home. Animals too migrate to escape danger but one group - the pond-living bdelloid rotifers - have taken this game of hide-and-seek to an extreme.
If they are threatened by parasitic fungi, they completely remove any trace of water in their bodies, drying themselves out to a degree that their parasites can't stand. In this desiccated state, they ride the wind to safety, seeking fresh pastures where they can establish new populations free of any parasites.
This…
edyong | January 19, 2010Deep beneath the ocean's surface lie the "black smokers", undersea chimneys channelling superheated water from below the Earth's crust. Completely devoid of sunlight, they are some of the most extreme environments on the planet. Any creature that can survive their highly acidic water, scorching temperatures and crushing pressures still has to contend with assaults from predatory crabs. What better place, then, to look for the next generation of body armour technology?
The scaly-foot gastropod (Crysomalion squamiferum) was discovered just 9 years ago at an Indian black smoker and it may have…
edyong | December 14, 2009
Octopuses are masters of camouflage that can change their shape, colour and texture to perfectly blend into their environment. But the soft bodies that make them such excellent con artists also make them incredibly vulnerable, should they be spotted. Some species have solved that problem with their fierce intellect, which allows them to make use of other materials that are much harder. The veined octopus, for example, dons a suit of armour made of coconut shells.
The veined octopus (Amphioctus marginatus) lives in sandy, exposed habitats that have little in the way of cover. To protect…
edyong | December 13, 2009There's a great octopus story coming your way tomorrow. For that reason, I thought it was about time to republish this - the first ever post I wrote for Not Exactly Rocket Science, about the ever-amazing mimic octopus. This article was a game-changer for me. I submitted it to the Daily Telegraph's Young Science Writer competition in 2004, while still struggling with a failing attempt at research. It was awarded a runner-up prize - not a win, but enough to convince me that I could actually write and that I enjoyed it. Looking back on it now, it's decent but a bit rough. It also took forever to…
edyong | November 9, 2009The female case-bearing leaf beetle Neochlamisus platani tries to give her children a head-start in life, but most mothers might not be keen on how she does it - encasing her young in an armoured shell made of her own faeces. After she lays her eggs, she seals each one in a bell-shaped case. When the larva hatches, it performs some renovations, cutting a hole in the roof and enlarge the structure with their own poo. By sticking its head and legs out, it converts its excremental maisonette into a mobile home, one that it carries around with them until adulthood.
All leaf beetles do this, but…
edyong | September 8, 2009When danger threatens many lizards can detach their tails, leaving them behind as decoys in the hope that the predator will attack it rather than the lizard itself. But the tail doesn't just lie there as bait. For half an hour after they've been severed, the disembodied tails perform a complex dance, flipping, lunging and jumping up to an inch in the air. These acrobatics serve to distract the predator even further.
For the first time, Timothy Higham and Anthony Russell have studied the movements of severed gecko tails to understand how they can move in such complex ways without any input…
edyong | August 21, 2009Viruses and bacteria often act as parasites, infecting a host, reproducing at its expense and causing disease and death. But not always - sometimes, their infections are positively beneficial and on rare occasions, they can actually defend their hosts from parasitism rather than playing the role themselves.
In the body of one species of aphid, a bacterium and a virus have formed a unlikely partnership to defend their host from a lethal wasp called Aphidius ervi. The wasp turns aphids into living larders for its larvae, laying eggs inside unfortunate animals that are eventually eaten from…
edyong | August 20, 2009
During chase scenes, movie protagonists often make their getaway by releasing some sort of decoy to cover their escape or distract their pursuer. But this tactic isn't reserved for action heroes - some deep-sea animals also evade their predators by releasing decoys - glowing ones.
Karen Osborn from the Scripps Institute of Oceanography has discovered seven new species of closely related marine worms (annelids) that use this trick. Each species pack up to four pairs of "bombs" near their heads - simple, fluid-filled globes that the worms can detach at will. When released, the "bombs" give…
edyong | July 31, 2009This article is reposted from the old Wordpress incarnation of Not Exactly Rocket Science.
An ant nest is sheltered, well defended and stocked with food, but one that takes time to build and protect. That's why some species of ants don't bother to do it themselves - they just squat in the nests of others.
These ants are 'social parasites' - they don't feed off their hosts' tissues, but instead steal their food, sleep in their homes and use their resources. They're like six-legged cuckoos
An ant colony is too dangerous a target to victimise lightly and the social parasites use several…
edyong | July 19, 2009It seems like an uneven match. In one corner, the unassuming California ground squirrel (Spermophilus beechyi), 30cm in length. In the other, the northern Pacific rattlesnake (Crotalus oreganos), more than twice the length of the squirrel, and armed with hinged fangs that pack a lethal venom. But thanks to a cunning adaptation, the squirrel often gets an unexpected upper hand in this bout.
Ground squirrels live in a series of burrows that keep them out of reach of most predators. Snakes, however, have exactly the right body plan for infiltrating long sinuous tunnels, and it's not surprising…
edyong | July 9, 2009The turtle's shell provides it with a formidable defence and one that is unique in the animal world. No other animal has a structure quite like it, and the bizarre nature of the turtle's anatomy also applies to the skeleton and muscles lying inside its bony armour.
The shell itself is made from broadened and flattened ribs, fused to parts of the turtle's backbone (so that unlike in cartoons, you couldn't pull a turtle out of its shell). The shoulder blades sit underneath this bony case, effectively lying within the turtle's ribcage. In all other back-boned animals, whose shoulder blades sit…
edyong | July 5, 2009Rising temperatures and high carbon dioxide emissions are the means through which humans are inadvertently causing the decline of several species. But one animal actively uses both heat and carbon dioxide as murderous weapons - the unassuming honeybee.
With their stings and numbers, bees already seem to be well-defended but they are completely outgunned by giant hornets (right). These two-inch long monsters are three times longer than several times heavier than tiny honeybees and raiding parties can decimate entire hives. European bees mount little in the way of an effective defence, but…
edyong | June 7, 2009Where there are plants, there are almost certainly aphids feeding on them. These ubiquitous insects are banquets for many predators, and some have evolved incredible defences against them. The cabbage aphid, for example, is a walking bomb.
Its body carries two reactive chemicals that only mix when a predator attacks it. The injured aphid dies. But in the process, the chemicals in its body react and trigger an explosion that delivers lethal amounts of poison to the predator, saving the rest of the colony.
The aphids' chemical weapons are stolen from the plants they eat. Far from being…
edyong | June 2, 2009In the darkness of the deep ocean, some animals create their own light. Among these is the Hawaiian bobtail squid Euprymna scolopes, which forms a partnership with the luminous bacterium Vibrio fischeri. The squid houses colonies of these bacteria in special light organs, and it can control the brightness and direction of their illuminations. But these organs do much more than produce light - they detect it too.
Deyan Tong from the University of Wisconsin has discovered that the organs generate nervous signals when they sense light and they're loaded with proteins responsible for detecting…
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 distinctive…
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 20, 2009There are so many fascinating stories about parasitic wasps that they have become a regular feature in this blog. Usually, their prey come off poorly in these tales, with caterpillars being reduced to little more than living, paralysed larders for macabre wasp grubs. But not always - some hosts don't take the invasion of their bodies lying down. This post is an attempt to redress the balance between parasite and host, by telling the story of the caterpillar that fights back... with medicine.
One species of tiger moth, Grammia incorrupta, has a fuzzy caterpillar called the woolly bear. Like…
edyong | February 19, 2009It's a scene straight out of a horror film - you look around and see dead bodies everywhere. They haven't just been killed either, they've been hollowed out from the inside-out leaving behind grotesque mummified shells. What would you do if you were confronted with such a macabre scene? Flee? Well, if you were an aphid, you'd probably just feel relieved and go about your business. Aphids, it seems, find security among the corpses of their peers.
Aphids, like almost all insects, are the targets of parasitic wasps that implant eggs inside their bodies. On hatching, the wasp grubs use the aphid…
edyong | February 7, 2009A couple of weeks ago, I wrote about a dolphin that has mastered the trick of killing cuttlefish and elaborately preparing them for a meal. It was a great story that highlighted just how intelligent and versatile dolphins can be, but it was a bit of a bittersweet report. The cuttlefish didn't exactly come out of it very well, which is a shame - they are intelligent creatures in their own right, every bit as fascinating as dolphins are. So it's with great glee that I report a new study that should help to restore the cuttlefish's credibility and cement its position as one of the cleverer…