| 释义 |
uro·chor·da
\ˌ ̷ ̷ ̷ ̷ˈkȯrdə\ noun plural
Usage: capitalized
Etymology: New Latin, from ur- (II) + chorda
: a subphylum or sometimes a class of marine animals (phylum Chordata) comprising the tunicates, including the orders Ascidiacea, Thaliacea, and Larvacea, and being distinguished by clefts in the vascular walls of the pharyngeal gills, by the secretion of a thick outer covering of tunicin for the body, by the reduction of the nervous system to little more than a single dorsally placed ganglion, and by a heart that so changes its contractions as to reverse the direction of the blood flow at intervals |