They have a one - way digestive tract and a blood - vascular system, and the sexes are separate.

它们具有 单向 消化道和血液循环系统, 雌雄异体.

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It'serves distinct yet complementary function with the blood vascular system in maintaining tissue homeostasis.

维持体内稳定,它属于血管系统,但也有其独立的功能.

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