Because their tissues are with the marine environment, jellyfish are

Because their tissues are isotonic with the marine environment, jellyfish are called as osmoconformers.

EXPLANATION:

Osmoconformers are the marine organisms that keep their internal fluid isotonic to that of their environment. They maintain a constant internal environment which is osmotic to their external environment. This means the osmotic pressure of the cells of an organism is equal to the osmotic pressure of their surrounding.

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