Head Butts & Waggle Dances: How Honeybees Make Decisions

Honeybees choose new nest sites by essentially head-butting each other into a consensus, shows a new study.

When scout bees find a new potential home, they do a waggle dance to broadcast to other scout bees where the nest is and how suitable it is for the swarm. The nest with the most support in the end becomes the swarm’s new home.

But new research shows another layer of complexity to the decision-making process: The bees deliver "stop signals" via head butts to scouts favoring a different site. With enough head butts, a scout bee will stop its dance, decreasing the apparent support for that particular nest.

This process of excitation (waggle dances) and inhibition (head butts) in the bee swarm parallels how a complex brain makes decisions using neurons, the researchers say.


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Turtles 'communicate with each other before hatching'

Scientists believe baby turtles can communicate with each other before they hatch and can arrange to emerge from their eggs at the same time.

A study of Australia's Murray short-necked turtle found the embryos synchronised their hatching to prevent smaller turtles emerging alone and being attacked by predators such as goannas and foxes.

It is believed the unhatched turtles, which lie enclosed in a tight nest, may be able to sense each other's heart vibrations or may detect gases emitted from the breath of other turtles. In this way, more developed turtles can send signals on their growth status to less developed ones to encourage them to increase their growth rates.

"I am pretty sure they're not sitting there chatting to each other but no one really knows," said Dr Ricky Spencer, a co-author of the new study.

The researchers, from the University of Western Study, said that embryos positioned at the bottom of the nest – where temperatures are lower – have a "catch-up mechanism" which enables them to overcome their longer incubation periods. However, the precise nature of the mechanism remains unknown.

"They might be cueing in on heart rates," Dr Spencer told ABC Radio. "They are all touching each other within the nests so there might be vibrations there. A nest environment is pretty much an enclosed cavity where gas exchange might be a cue as well ... They breathe, so if you get increases in carbon dioxide within a nest they might be cueing on in that."

The researchers studied the turtles by dividing a clutch of eggs into two and incubating them at different temperature levels. They then united the eggs after a week and analysed the embryonic heart rates and metabolic rates. During the last third of the incubation period, the cooler embryos had sped up their heart rate and metabolism and hatched within a couple of days of the warmer ones.

"They increased their developmental rate essentially independent of temperature [and] that allowed them to hatch earlier," Dr Spencer said.

http://www.telegraph.co.uk/news/newstopics/howaboutthat/8925107/Turtles-communicate-with-each-other-before-hatching.html

Meerkats recognise others' voices

Meerkats recognise another member of their social group by the sound of their voice, according to scientists.

Researchers studying the animals in the Kalahari Desert, South Africa, played recordings of meerkat calls and observed the animals' reactions.

Their discovery, reported in the journal Biology Letters is the first evidence of a non-primate mammal showing vocal recognition in the wild.

The phenomenon could be more widespread in the animal kingdom than thought.

"There's lots of evidence of vocal recognition in primates," explained lead researcher Dr Simon Townsend from the University of Zurich in Switzerland.

"[In primates] you can really test whether they respond to individual vocal recognition."

But this harder to test in other non-primates, he explained, because relationships between individual animals are not as clear.

In meerkats, for example - although they are social animals that live in groups and forage and even raise young together - it is not entirely clear how one animal will respond to another when it hears its call.

To solve this problem, the researchers used a simple audio playback experiment.

They used recordings of the staccato "close calls" that meerkats make continually while they are foraging. "We think the calls mainly function to keep the group together," said Dr Townsend. "But they also tell other individuals, 'I'm here, this is my patch'."

The scientists placed speakers on either side of a foraging meerkat, and played a call from a member of their social group. A few seconds later they played the call of a different member of the same group through a speaker on the opposite side.

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Piranhas communicate with sound, say researchers

Despite a nasty reputation, piranhas seem to bark more often than bite.

Scientists have discovered that the fearsome fish use sounds to communicate - often intimidating their rivals rather than attacking.

With underwater microphones, scientists recorded the sounds the fish made when they confronted one another.
They reported in the Journal of Experimental Biology that each of these three sounds appeared to contain a different "message".

Lead researcher Eric Parmentier, from the University of Liege, Belgium, has studied sound production and communication in a wide variety of fish species, including the charismatic clownfish and the spectacularly ugly toad fish.

He already knew that piranhas made sounds, but wanted to understand why.

Many fish use noises to attract a mate, so the sounds are an important indicator that the fish are reproducing.

"Eventually, if we understand the behaviour that's associated with the sounds, we might be able to listen to the sea and explain to fishermen: 'Now's not the best time to start fishing'."

Dr Parmentier and his colleagues put a hydrophone - an underwater microphone - into a tank of piranhas in their lab and filmed the fish as they interacted.

They recorded three distinct sounds. The first was a bark that the fish produced when they "displayed" to each other - confronting one another face to face but not fighting.
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