noun
deuterostome
A zoological term for animals in which the first embryonic opening becomes the anus. Contrasts with 新口動物 (protostome).
See also: 新口動物
ヒトを含む脊椎動物は後口動物に分類される。
Vertebrates, including humans, are classified as deuterostomes.
新口動物 (protostome) is the contrasting group where the first embryonic opening becomes the mouth.
From 後口 (こうこう, 'hind opening') + 動物 (どうぶつ, 'animal'), referring to the embryonic development pattern where the anus forms first.