ambulacrum (amb) In Echinodermata, an area of the body surface (covered in most classes by calcitic (see CALCITE) plates), that overlies one of the radial canals of the internal water vascular system, and bears the tube feet. In some echino-derms, e.g. Asteroidea, Blastoidea, and Crinoidea, the ambulacrum is marked by a deep linear depression, the ambulacral groove. Typically, echinoderms have five ambulacral areas, or a multiple of five. See ECHINOIDEA.

ambulacrum (amb) In Echinodermata, an area of the body surface, in most classes covered by calcitic plates, that lies over one of the radial canals of the internal water-vascular system and bears the tube feet. In some echinoderms (e.g. Asteroidea, Blastoidea, and Crinoidea) the ambulacrum is marked by a deep linear depression, the ambulacral groove. Typically, echinoderms have five, or a multiple of five, ambulacral areas.

ambulacrum.
1. Atrium, court, or parvis, sometimes with a fountain in the centre, surrounded by arcades or colonnades, and often planted with trees, in front of a basilica.

2. Any walk or avenue with formally arranged tree-planting.