Shrimps’ half a billion year-old dance might be earliest known group behaviour

An analysis of a newly discovered caravan of crustaceans from half a billion years ago suggests that group behaviour evolved not long after animals themselves, say experts.

Fossilised chains of up to 20 crustaceans linked head-to-toe were discovered by a team research team palaeontologists, led by Hou Xian-Guang of China-based Yunnan University.

The discovery appeared to be the earliest record of any collective animal behaviour, and perhaps an adaptation to a migratory ocean lifestyle.

“It’s showing that, 525 million years ago, we’ve got really quite sophisticated and potentially complex interaction between different animals,” New Scientist magazine quoted Derek Siveter of the University of Oxford, who analysed the fossil along with colleagues at the University of Leicester, UK, as saying.

Based on their observations, the researchers came to the conclusion that the undulating procession of ancient arthropods, each about two centimetres long, represented more than a quirk of fossilisation.

Though none of their arms, legs or antennae survived a half billion years in stone, the animals probably interlocked appendages to stay together.

“We hypothesise that the chain was in the water column and it met its demise by whatever reason or forces, then it sunk to the bottom,” Siveter said.

Modern creatures called sea squirts are known to form long chains to boost mating opportunities, but Siveter doubts that his crustaceans engaged in a carnal dance because no modern crustaceans show this behaviour.

He also doubts whether group feeding underpinned the collective behaviour because animal’s mouth appears blocked by its neighbour’s tail.

“The simplest explanation for this is that it is some kind of collective behaviour coming together for migration, perhaps associated with defence in numbers,” he said.

Iain Couzin, a biologist at Princeton University, said: “Finding an example of collective behaviour so long ago is really eye opening to us.”

He revealed that his team was trying to develop computer models to understand the evolution of group action, which seemed to arise often and with little individual complexity needed.

“Collective behaviour is all around us and it’s also within us, the function of cells within in the body is a form of collective behaviour,” he said.

A research article on the study has been published in the journal Science. (ANI)