Thin atmosphere with low oxygen and carbon dioxide levels
Answer:
The circulatory system of the crayfish is an open system where the blood is contained in vessels for only part of the system. The heart is located in a pericardial sinus located in the upper part of the thorax (a sinus is a sac or cavity). The heart pumps the blood into the arteries.
Explanation:
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B/biosphere oh i can’t answer without 20 letters
Answer:
its "A" water flowing over a tall cliff
Explanation:
