Article: A functional classification of the coronal pores of regular echinoids

Six morphologically distinct types of ambulacral pore, found in a survey of Recent regular echinoids, are described and correlated with the structure of their tube feet. A functional interpretation of pore structure provides considerable information about the tube foot supported and allows the reconstruction of tube feet from fossil echinoid tests. Morphological information, such as the presence or absence of a septum, the thickness of the stem retractor muscle, the presence or absence of a terminal sucking disc and the size of that disc, can all be inferred from the structure of the ambulacral pores. Ecological interpretations concerning the animal's life style, the energy of the environment, the nature of the substrate, the depth, and the temperature can all be advanced once the form of tube feet can be identified. In Britain all but the simplest coronal tube feet make their appearance during the Jurassic.