| 释义 |
as·cid·i·an
\-ēən\ noun
(-s)
Etymology: New Latin Ascidia (II) + English -an
: a simple or compound tunicate of the order Ascidiacea suggesting as a larva a minute active tadpole with an elongated tail that contains a distinct notochord and dorsal nerve chord showing obvious relationship to the vertebrates but as an adult lacking the tail and being reduced to a sessile saclike form with an anterior branchial opening through which water passes to a branchial sac having perforated walls which strain microscopic food into the digestive tract before the water emerges by way of an atrium and dorsal atrial opening; broadly : tunicate |