Left–right asymmetries of behaviour and nervous system in invertebrates

<p>Evidence of left–right asymmetries in invertebrates has begun to emerge, suggesting that lateralizationof the nervous system may be a feature of simpler brains as well as more complex ones. A variety ofstudies have revealed sensory and motor asymmetries in behaviour, as well as asymmetries in the nervoussystem, in invertebrates. Asymmetries in behaviour are apparent in olfaction (antennal asymmetries) andin vision (preferential use of the left or right visual hemifield during activities such as foraging or escapefrom predators) in animals as different as bees, fruitflies, cockroaches, octopuses, locusts, ants, spiders,crabs, snails, water bugs and cuttlefish. Asymmetries of the nervous system include lateralized positionof specific brain structures (e.g., in fruitflies and snails) and of specific neurons (e.g., in nematodes). As invertebrates, lateralization can occur both at the individual and at the population-level in invertebrates.Theoretical models have been developed supporting the hypothesis that the alignment of the direction ofbehavioural and brain asymmetries at the population-level could have arisen as a result of social selectivepressures, when individually asymmetrical organisms had to coordinate with each other. The evidencereviewed suggests that lateralization at the population-level may be more likely to occur in social speciesamong invertebrates, as well as vertebrates.</p>