The podia, also known as tube feet, are highly specialised structures that aid echinoderms in locomotion, fixation, burrowing as well as adhering to substrates (Santos et al. 2005). The anatomy of tube feet consists of a basal extensible cylinder, or stem, which expands to form an apical flattened disc or ‘sucker’ (Santos et al. 2005) (Figure ). Each tube foot consists of four tissue layers that are specialised for adhesion and sensory perception : the inner myomesothelium, a connective tissue layer, the nerve plexus and the outer epidermis that is covered by the cuticle (Santos et al. 2005)(Figure ).

As tube feet may perform different functions, the shape or form of tube feet of various echinoderms often correspond to a particular function. Asteroid tube feet may be identified by two existing forms – ‘knob-ending’ podia that have pointed tips and ‘disc-ending’ podia that have flattened tips (Santos et al. 2005)(Figure ). The tube feet of Gomophia watsoni are that of the latter, having very distinct, flattened suckers at the tip of the podia. The variation in tube feet shape and form may therefore correspond to the substrate type or environment they are likely to inhabit, such as soft or hard substratum. Given that G. watsoni inhabits rough surfaces such as rocks, it is therefore fitting that it bears disc-like suckers.