The pit organs of elasmobranchs: a review

Elasmobranchs have hundreds of tiny sensory organs, called pit organs, scat tered over the skin surface. The pit organs were noted in many early studie s of the lateral line, but their exact nature has long remained a mystery. Although pit organs were known to be innervated by the lateral line nerves, and light micrographs suggested that they were free neuromasts, speculatio n that they may be external taste buds or chemoreceptors has persisted unti l recently Electron micrographs have now revealed that the pit organs are i ndeed free neuromasts. Their functional and behavioural role(s), however, a re yet to be investigated.