Food
sea creatures, mostly fishes are also used aa our food. these fishes have a lot of nutrients such as DHA,omega-3 fatty acids and vitamins such as D and B2 (riboflavin).
these nutrients are pretty important for our human body, and there are still nutrients that only can be gotten from fishes. Therefore, we have to take care of fishes.
Food chain
The sea creature does a important job in our food chain. Most sea contains microorganism that can biodegrade the dead meat and other stuff. They are like the cleaner of the sea, and they are super important.
After that, those microorganisms will be eaten by a plankton, then to fishes, and so on. This cycle keeps the sea to have too much fishes or too less fishes.
Medicine
sea creatures also provides us with a chemical that can be used to make medicines. these medicines can cure cancer, pain and other ailments. These medicines are pretty useful and they also can be said as a gift from sea.
However when fishes die, these medicines will not be able to use a lot of times, and there will be a problem for the ones who really need this medication.