Fishes gills are engorge in blood , as water is pumped over it as the fish swims, it pulls water thru it's mouth and pushes it over it's gills extracting oxygen and the used water is ejected thru the fish slits opening that cover and protect the gill. the blood is circulated thru the fish body.
Oceanography is basically a ocean ecology. In oceanography you study the oceans, and everything in it. It also studies, apart from animals and plants, such as other water-related things like waves and currents.
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Answer:srry just need points
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Answer:
It maintains genetic variability in a species.
Explanation:
