Thursday 27 October 2016

Woodlice have personalities, analysis of Percellio scaber species suggests

Published 02/08/2015 | 07:47

Scientists testing the way woodlice react to being prodded, squeezed or dropped found they display different personalities
Scientists testing the way woodlice react to being prodded, squeezed or dropped found they display different personalities

It may be small, grey and easy to ignore, but the humble woodlouse is big on personality, according to new research.

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Dogs can be friendly or hostile, cats aloof or affectionate, and horses moody - but woodlice? They are individual characters too, scientists claim.

Tests on the way the creatures respond to being prodded, squeezed and dropped show that some are bold and others timid.

Even taking account of influences such as body size, they display behaviours that meet the definition of "personality", said the researchers.

The Czech team observed how the common rough woodlouse, Porcellio scaber, did what woodlice often do when threatened - feign death by curling up their armoured segmented bodies and tucking away legs and antennae.

Different individuals were more or less willing to adopt the "tonic immobility" (TI) strategy, some curling up for longer than others.

The way they differed was consistent across the range of tests, and when the experiment was repeated five times over a three week period.

Writing in the journal ZooKeys, the scientists led by Dr Ivan Hadrian Tuf, from Palacky University, Czech Republic, said: "There were some consistently more 'bold' woodlice (short TI) and some more 'shy' woodlice (long TI) ..

"Besides finding differences in endurance of TI between body size groups, we also identified personal behavioural patterns in all tested individuals, as well as variation within these body size groups."

They concluded: "Porcellio scaber is one of the first species of terrestrial isopods with documented personality traits."

Personality in animals has been defined as individual behavioural characteristics that are consistent over time in response to different situations.

Woodlice may look like insects but are actually isopod crustaceans related to crabs and lobsters.

There are thought to be about 3,500 species of woodlouse in the world, 35 to 40 of which can be found in the UK.

Dr Tuf's team captured several hundred woodlice from gardens and parks in the medieval Czech city of Kutna Hora.

Placed in plastic boxes, the creatures' responses were observed when they were gently nudged or grabbed with forceps, or dropped from a height of 10 centimetres.

Curling up is not the only defensive strategy employed by woodlice. In the tests, 77% of the animals tried to run away or deployed their secret chemical weapon, a bad-smelling liquid that deters spiders.

The scientists were not able to determine whether woodlouse personality changed over time.

They wrote: "These findings are not able to resolve if personality is changing during individual development or not .. Investigation of long-time stability of behavioural traits in terrestrial isopods should be a possible goal of future studies."

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