AMBULACRUM
ambulacrum
(noun) one of the five areas on the undersurface of an echinoderm on which the tube feet are located
Source: WordNet® 3.1
Etymology
Noun
ambulacrum (plural ambulacrums or ambulacra)
(of an echinoderm) A row of pores for the protrusion of appendages such as tube feet.
Source: Wiktionary
Am`bu*la"crum, n.; pl. Ambulacra. Etym: [L., an alley or covered
way.] (Zoöl.)
(a) One of the radical zones of echinoderms, along which run the
principal nerves, blood vessels, and water tubes. These zones usually
bear rows of locomotive suckers or tentacles, which protrude from
regular pores. In star fishes they occupy the grooves along the under
side of the rays.
(b) One of the suckers on the feet of mites.
Source: Webster’s Unabridged Dictionary 1913 Edition