Spitting Cobra anticipates your every move

The spitting cobra – feared for its ability to blind by spraying venom into the eyes of its victims – anticipates the movements of its target, ensuring its venomous spray hits the mark every time.

It's watching you... A red spitting cobra. Image: Pogrebnoj-Alexandroff/Wikimedia

There are several species of spitting cobra, all of which live in Africa. None of them can control the direction of the stream of venom they can fire from tiny forward-facing holes in their fangs. Instead, the snakes must move their entire head to track the target. At the moment of attack, however, the snake stops tracking and instead anticipates where the targets’ eyes will be 200 milliseconds later – the length of time it takes the snake to launch the venom.

A team of German and American scientists spent six weeks goading a spitting cobra to fire streams of venom at a researcher wearing a protective mask while they filmed the snake using a high speed camera to capture 500 frames per second. They found that a sudden movement from the target triggers the spitting attack. At this point the snake can be reasonably sure where the target will be by the time the snake can release its venom, ensuring the venom lands with pinpoint accuracy.

The spitting cobra’s predictive skills are surprising as the precise planning required to do so was thought to be beyond its relatively simple reptilian brain.

So how can you ensure the snake doesn’t spray venom into your eyes should you ever encounter one? Simply don’t poke it with a stick, or disturb it in any way. Spitting cobras don’t use their venom spray aggressively; it’s purely a defensive strategy used to deter predators and other irritating large animals…

Paper Reference: Westhoff, G., Boetig, M., Bleckmann, H. and Young, B. A. (2010). Target tracking during venom ‘spitting’ by cobras. Journal of Experimental Biologists. 213, pp 1797-1802. doi: 10.1242/jeb.037135

Owls sing to the moon

Eagle owls use the moon to talk to one another at night, according to a European team of researchers. They found that Eurasian eagle owls (Bubo bubo) call more on moonlit nights, when the moonlight illuminates the white patch of feathers they expose only when calling out loud.

The  owls rely mostly on a vocal call to communicate, but drive home the message with a flash of white feathers. The owl’s call, together with the bright white feathers, makes them rather noticeable in the dark of the night.

Eagle Owls: wolves in owl's clothing? Image: Hypothesis Now

The owls also favour higher perches on moonlit nights, presumably taking advantage of the more exposed position to make the most of the light shining on their stark white feathers. In contrast, the owls were often silent on moonless nights and, if they did call, the owls tended to do so from a lower perch.

Many animals alter their behaviour depending on the phases of the moon. Usually, bright nights make it easier for predators to find prey, so small animals keep quiet when the moon is full. Eagle owls, however, have no natural predators so they’re free to make themselves as eye-catching as possible to ensure nearby owls get the message. They usually communicate most at dusk and dawn, but a full moon produces almost as much light and the owls have learned to take advantage of it to call long into the night.

It may sound obvious, but the point of signalling is to be understood, and animals have evolved lots of clever tricks to get their messages across: many other birds have repeating calls, so the message is repeatedly broadcast; Anole lizards bob their heads to make themselves stand out from the background; and poisonous insects often use bright contrasting colours to warn off prospective predators. The eagle owls have simply learned to take advantage of another source of light.

Paper reference: Penteriani, V.,  Delgado, M.d.M.,  Campioni, L.,  Lourenço, R. (2010) Moonlight Makes Owls More Chatty. PLoS ONE 5(1): e8696. doi:10.1371/journal.pone.0008696

Regular gamers have rapid reactions

Many computer games require quick reactions: whether it’s negotiating a hair-pin bend or dodging the swing of a Minotaur’s axe, the faster a player can react, the better they’ll do. It also turns out that the quick reactions learned in action-heavy games carry over to real life, according to a recent study by American researchers.

Are all of those hours playing games good for you? Image: Hypothesisnow

By looking at many different studies published by others, the researchers compared the reaction times and accuracy of regular action game-players to those of novice gamers. Regular action game-players performed, on average, 11% faster on a range of tests designed to measure reaction times.

So gamers are fast, but do they gain their speed boost at the expense of accuracy? The data would suggest not. In fact, the accuracy of both regular gamers and novice gamers was almost identical, at 92.76% and 92.75%.

The researchers also carried out a simple experiment to test their findings: a group of novice gamers were asked to play action games (Unreal Tournament and Call of Duty 2, in this case) for fifty hours over eight or nine weeks. The gamers improved their reaction times by around 13% while maintaining the same level of accuracy when compared to novice gamers given The Sims to play in the same period of time.

So playing action games regularly can train gamers to react to what they see – known as visual processing – faster than non-gamers, or even when compared with gamers whose preferred games don’t rely on quick reactions. Speedy visual processing has been linked to better reasoning and judgement, so playing action games might help elderly people retain their mental agility for longer. It could even help people who have suffered brain injuries by boosting their mental performance. Unfortunately, the researchers point out that the content and difficulty of many modern games means they’re probably not suitable for therapeutic uses in young or elderly patients.

So we probably won’t ever see doctors prescribing a course of Modern Warfare 2 for elderly patients, or a few laps of the track on Colin McRae for people suffering head trauma.  For now, it’s just good to know all those hours of gaming are doing us all some good!

Warmer seas anger fish

Do you find yourself becoming more agitated and aggressive on hot days, or do you keep your cool no matter what the weather does? A recent study of damselfish (Pomacentrus moluccensis) on Australia’s Great Barrier Reef has shown that the personalities of these brightly coloured fish are directly affected by the temperature of the water in which they swim. The study implies that relatively small changes to the environment can have major impacts on the behaviour of some animal species.

What lurks behind this calm exterior? Image credit: Flickr/danielguip

The researchers studied three fishy personality traits: activity, boldness in the face of a predator, and aggressiveness to other fish of the same species. Relatively small changes in temperature (of less than 3^oC) caused significant changes to these three personality traits in individual fish. Intriguingly, not all of the fish were affected equally: some of the most docile fish became much more aggressive at higher temperatures while other showed much less change in personality.

But why do some fish become bolder and more aggressive at higher temperatures?

The researchers believe it’s down to their basic biology: fish are cold-blooded (or ectothermic), which means their bodies are at the same temperature as their surroundings as they cannot generate their own body-heat, unlike mammals such as ourselves. An increase in water temperature warms the fish up, speeding up its metabolism and forcing the fish to forage more for food to support itself. Being active, bold and aggressive makes it easier to find more food, although it also increases the risk of the fish being caught by a predator.

This is the first time anyone has shown a link between temperature (and therefore metabolism) and personality. It suggests any future studies of ectotherms, which make up most of the animal kingdom, must control temperature very carefully to make sure it doesn’t alter their results.

The study also raises an important question: what would happen to these fish if climate change warmed the oceans by a few degrees? The researchers can’t say for certain, but bolder fish are taken more often by predators. As this causes overall survival rates to drop, fish populations could change dramatically.

Paper reference: Biro, P., Beckmann, C., and Stamps, J., 2010. Small within-day increases in temperature affects boldness and alters personality in coral reef fish. Proc. R. Soc. B. 277, 71-77. doi: 10.1098/rspb.2009.1346

Apparently, to celebrate their 350^th anniversary, the Royal Society are giving free access to all of the papers published in Proceedings of the Royal Society B, so get stuck in!

Australia's Great Barrier Reef is one of the most diverse ecosystems in the world. On hot days, you can just feel the aggression from all those fish! Image: Hypothesis Now

The social life of plants

Plants aren’t the first thing most people think of when talking about social interactions. They don’t have the complex social lives of many animals, and have few opportunities to meet new people, yet plants do interact socially. A study by Canadian researchers has shown that plants become much more competitive when they’re growing next to unrelated plants, putting out extra leaves and trying to out-compete their rivals.

Impatiens pallida: recognising the importance of family. Image: Wikimedia/SB Johnny

Researchers have known for a while that plants can recognise other related plants growing nearby. The new study shows that one species of plant, known as Impatiens pallida, actually responds to the presence of ‘family’ by producing fewer leaves and more branches and longer stems. Fewer leaves means less competition for light – suggesting the two plants are cooperating.

In contrast, when I. pallida was grown with an unrelated neighbour of the same species it put much more effort into growing leaves, competing with its neighbour for the available light. The effect was only seen when the two plants were grown in the same pot; without root contact between the plants there was no change in growth. Researchers still don’t know, however, exactly how plants recognise kin.

I. pallida’s response to competition is perfectly adapted to its natural surroundings. It prefers dark, shady spots where light is the only thing limiting the speed at which it can grow. In this case, competition means a battle for the scant available light. The related species I. edentula grows in the open, often on beaches, where there are very few nutrients in the sandy soil. When faced with competition, I. edentula sprouts extra roots, to extract as much as possible from the soil to give itself a boost.

In animals, a lot of cooperative behaviour is seen between close relatives (think of prides of male lions, who are usually brothers, or massive ant colonies – which contain mostly sisters and mothers). Relatives share many similar genes, so by helping brothers and sisters reproduce, an individual can ensure at least some of their own genes are passed on to future generations. Unrelated individuals share fewer genes, so there’s no reason to cooperate. This is known as kin selection, and is a powerful driving force for altruistic behaviour – in both plants and animals!

Paper reference: Murphy, G., and Dudley, S., (2009) Kin Recognition: competiton and cooperation in Impatiens (Balsaminaceae). American Journal of Botany, 96(11).  1990–1996. DOI:10.3732/ajb.0900006