CAP organs are the crustacean equivalent of insect hair plates. In the lobsterHomarus gammarusthey are located at the IM (ischium‐merus), MC (merus‐carpus) and CP (carpuspropus) joints on the distal side of the articulation. They are typically fan‐shaped and composed of numerous peg‐like sensillae. The numbers of individual sensillae in each organ increase with size of the animal.