Marine isopod on plastic waste. Isopods are crustaceans found on sea and land. The marine isopods are mostly found on the seabed, though some are parasitic on other marine organisms. This one is riding on a piece of plastic waste floating in the water. Plastic waste is typically not biodegradable and persists in the environment if not disposed of correctly. Plastic waste can have a severe long-term effect on the marine environment, both as large items that can choke and entangle animals, and as it breaks up into microscopic fragments that can enter the food chain. Photographed in the Mediterranean Sea.