a small elongated marine invertebrate that resembles a fish but lacks jaws and obvious sense organs. Lancelets possess a notochord and are among the most primitive chordates 文昌鱼
Subphylum Cephalochordata, phylum Chordata: several species, including amphioxus 头索动物亚门,脊索动物门:数种,包括文昌鱼
语源
mid 19th cent.: from the noun lance (because of its long narrow form) + -let