Plastics burns and releases a lot of energy during that process. In that regard its energy density is similar to wood. The problem is that compared with cellulose the life has not figured out how to harvest the energy of plastic oxidation at the room temperature. But there is no law that prevents that.
Given that amount of plastic waste that humans put into the ocean is already on the scale comparable with a mass of a lot of fish species, an organism that can consume it can have a nice evolutionary advantage.
Given that amount of plastic waste that humans put into the ocean is already on the scale comparable with a mass of a lot of fish species, an organism that can consume it can have a nice evolutionary advantage.