noun
protochordate
A zoological term for primitive chordates, including tunicates and lancelets. Used in academic and biological contexts.
原索動物は脊索動物の一群で、ホヤやナメクジウオが含まれる。
Protochordates are a group of chordates that includes sea squirts and lancelets.
脊索動物 (chordates) is the broader phylum; 原索動物 is a subgroup of primitive chordates.
Compound of 原 (primitive) + 索 (cord) + 動物 (animal), referring to the primitive notochord. The exact historical derivation is uncertain.