ABSTRACT
Functional morphology of the penicillate podia of the burrowing echinoid Echinocardium cordatum (Echinodermata).
Phyllopodes and preapical podia are the two main types of penicillate podia of Echinocardium cordatum. They basically consist of an extensible shaft topped by a disc with slender digitate extensions. Phyllopodes are food-collecting podia; their disc surfaces are covered by densely packed club-shaped digitations. Preapical podia build up the burrow’s funnel and undertake the maintenance of its wall; their disc surfaces are flat with blunt-tiped digitations located at the disc margin. A thick and well innervated glandular epiderm occurs either at the tip of the digitations (phyllopodes) or on the whole disc surface and the inner side of digitations (preapical podia). It is suggested that these particular epidermal areas could produce adhesive/de-adhesive secretions that would facilitate sediment handling by penicillate podia.
