Explanation:
Porifera (sponges) are characterized by the presence of a complex water canal system (canal system) used for food gathering, respiratory exchange, and waste removal. Water enters through numerous small pores called ostia and exits through a large opening called the osculum. They are mostly marine and asymmetrical.
Explanation:
Fossils are the preserved remains or impressions of past organisms, showing transitional forms and evolutionary change over geological time.
Explanation:
ANP is secreted by atrial muscle cells of the heart in response to stretching (high blood volume). It promotes sodium and water excretion, lowering blood pressure. Kidneys secrete renin, adrenal aldosterone, liver angiotensinogen.
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