The primary producers creatures that makes their own food like plants.
A Swim Bladder is not present in cartilaginous fishes. Also called a fish maw or gas bladder the swim bladder is a gas-filled bladder that allows many bony fish to control their buoyancy by filling or releasing gas form the bladder. This allows them to change bouyancy without wasting metabolic energy by swimming.
A scientific theory. Obviously, the hypothesis would need a considerable amount of increased testing to be proven a scientific law. But, even so, it could become a theory.
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