question: What differentiates placozoans from the ctenophora and the cnidaria ?
answer: they do not have a permanent digestive chamber
turker_answer: The fact that they do not have a permanent digestive chamber differentiates placozoans from the ctenophora and the cnidaria .
rule-based: They do not have a permanent digestive chamber differentiates placozoans from the ctenophora and the cnidaria .