animal behaviour

Quiet Please, the Fish Are Flirting

Fish that fart together stay together.

In an ocean full of clicking shrimp and singing whales, fish are often imagined as the silent actors. Fish use motion, color, and chemicals to communicate, but they lack the iconic mewl of a cat or trill of a bird. Yet in reality, many fish chat constantly to mark their territories or find mates. And all of our noise—from seismic surveys to boat motors—is making it much more difficult for fish to hear one another. Read more in Hakai Magazine.

Wise elk learn to outsmart hunters and tell apart their weapons

As female elk get older, they also get wiser: they learn how to avoid getting shot by hunters, and appear to adapt their behaviour to the types of weapon the hunters carry.

Hunting by humans is known to affect how elk behave, selecting for more cautious behaviours by killing more of the bolder animals. But ecologist Henrik Thurfjell at the University of Alberta, Canada, wondered whether the animals might also learn how to stay safe as they age. Read more in New Scientist.

Monkey mafia steal your stuff, then sell it back for a cracker

Long-tailed macaques living near an Indonesian temple have figured out how to run a ransom racket on visiting tourists.

The monkeys grab valuables, such as glasses, hats, cameras or, in one case, a wad of cash from the ticket booth, then wait for temple staff to offer them food before dropping their ill-gotten gains and dashing off with the tasty prize. Read more in New Scientist.

Isolated crayfish are more resistant to the effects of alcohol

For crayfish at least, a more sociable life makes booze work quicker. When crayfish were put in water containing a little alcohol, the ones who had been kept on their own over the preceding week took longer to show signs of alcohol exposure – such as tail flips – than those who had been living with others of their kind. Read more in New Scientist.

Dogs use deception to get what they want from humans (a sausage)

Dogs are all honest, loyal and obedient, right? Well, not always. Our pets can be sneaky and manipulative when they want to maximise the number of tasty treats they get to eat.

Marianne Heberlein, who studies dog cognition at the University of Zurich in Switzerland, wanted to test the animals’ ability to use deception to get what they want from humans. Read more in New Scientist.

The devoted spider dads who fix up nurseries for their babies

Most male spiders bail out after mating – if they make it through the process alive, that is, as females of many spider species cannibalise their mates.

But not this spider. Male Manogea porracea in South America not only help with childcare, they often end up as single dads. Read more in New Scientist.

Sword-slashing sailfish hint at origins of cooperative hunting

Cooperation makes it happen. Sailfish that work together in groups to hunt sardines can catch more fish than if they hunt alone, even without a real coordinated strategy.

To catch their sardine dinner, a group of sailfish circle a school of sardines – known as a baitball – and break off a small section, driving it to the surface.

They then take turns attacking these sardines, slashing at them with their long sword-like bills, which account for a quarter of their total length of up to 3.5 metres. Knocking their prey off-balance makes them easier to grab.

These attacks only result in a catch about 25 per cent of the time, but they almost always injure several sardines. As the number of injured fish increases, it becomes ever easier for everyone to snag a meal. Read more in New Scientist.

Chimps and bonobos interbred and exchanged genes

Chimpanzees and their relatives bonobos are closer than we thought. Bonobos seem to have donated genes to chimps at least twice in the roughly two million years since they last shared an ancestor.

The two closely related apes have occasionally interbred in captivity, and bonobos are renowned for their free and easy sex life. But the finding that they interbred in the wild was unexpected. Read more in New Scientist.

Surfing on a turtle’s tail makes swinging crabs monogamous

Surfing the world’s oceans on the back of a turtle may sound like a life of luxury, but for a small crab it also means restricting itself to a single mate.

A species of small oceanic crab, Planes minutus often makes its home on the shells of loggerhead turtles. They tuck themselves into a tiny space above the turtle’s tail and below the shell, just the right size for a pair of crabs – a male and a female living in a simple monogamous relationship.

But these crabs will also make their homes on floating debris, where they nestle among stalked barnacles, and often enjoy a more swinging, polyamorous lifestyle. Read more in New Scientist.

Rattlesnakes silently shook their tails before evolving rattles

Shake, rattle and strike. It is possibly one of the most terrifying sounds in the animal kingdom, but how the rattlesnake evolved its chilling warning signal is a mystery. Now a study suggests the rattle evolved long after the tail-shaking behaviour.

The evolution of the rattle has baffled scientists because, unlike other complex physical traits like eyes or feathers, it has no obvious precursor or intermediate stage.

“There is no half-rattle,” says David Pfennig at the University of North Carolina at Chapel Hill. Read more in New Scientist.