1. In echinoderms (such as starfish and sea urchins), one of the radial grooves or bands on the body surface through which tube feet extend for movement and feeding.
Usage: zoology; technical; plural: ambulacra
2. A covered walkway or portico in ancient Roman architecture.
Usage: architecture; historical; plural: ambulacra or ambulacrums

Examples

• The starfish uses its ambulacra to move slowly across the ocean floor.
• Each ambulacrum of the sea urchin contains rows of tube feet.
• The ambulacra in echinoderms are arranged in a radial pattern around the body.
• Roman villas often featured an ambulacrum where residents could walk and exercise.
• The ambulacrum provided shelter from the sun while allowing air circulation.
• Scientists study the ambulacra of fossil echinoderms to understand their evolution.