how ae marine invertebrates and fishes able to live at great depths in oceans where pressure could be 100 times the normal atmospheric pressuure that we experience? how do they live under such crushing pressures?

The greatest effect that increasing atmospheric pressure at great depths in ocean has on marine organisms is in the compression of lungs. Marine invertebrates such as worms, crustaceans, and sea cucumbers, are not affected by this change in pressure as they lack gas-filled cavities or lungs. As far as fish are concerned, they possess a variety of physiological adaptations, which help them to remain underwater for long periods of time. Their streamlined shapes helps them in reducing oxygen consumption, possess higher concentration of the protein myoglobin, which binds oxygen in muscle tissue. The cell membrane of these organims have more number of unsaturated fatty acids to increase the fluidity and their enzymes have specific structure. Most of the enzymes are monomeric and they have amino acids that make strong non covalent bonds between them to increase the stability.