Deuterostomes are distinguished by their embryonic development ; in deuterostomes , the first opening -LRB- the blastopore -RRB- becomes the anus , while in protostomes it becomes the mouth .

Deuterostomes are distingued by their embryo , in deuterostomes , the first opening -LRB- the blastopore -RRB- becomes the anus , while in protostomes it becomes the mouth .
