Antennal mechanosensors and their evolutionary antecedents

Insect antennae are modified legs that serve critically important olfactory and mechanosensory roles. Although the antennae are highly developed sensory appendages with multi-modal functions, they share many morphological, neurobiological and functional traits with the legs. A comparison of these traits is informative from several perspectives. First, it enables us to lay down some general rules about how mechanosensory feedback is used in guiding the movement of these appendages. Second, it helps generate hypotheses with testable predictions for the role of homologous mechanosensory organs in legs and antennae. Third, it provides key insights into the evolution of the multi-sensory antennae in the context of their diverse shapes and sizes. Here, we provide a detailed account of the mechanosensory and motor apparatus of legs and antennae and compare their structure and function. Such a comparison is useful in understanding the evolution of the antennae as an important sensory organ