Living in the ocean? Fish has a slender body and a long oval sucker on its head, which looks like a seal, hence its name. Don't underestimate this "seal". What is it? An important tool for fish to travel easily and eat for free. Whenever sharks, turtles or some big fish swim nearby, The fish is stuck on it with a sucker, adsorbed on the big marine animals and swam around, and at the same time, the residue of the big animals preying on their prey fills their stomachs. Because? There are meat folds in the sucker of fish. When other big marine animals are attached, the water inside the meat folds is squeezed out, which produces suction under the pressure of seawater, so the adsorption force is very strong and it will not be easily separated. So that it can "travel for free" with the travel of big fish or ships. When it meets a sea area with a lot of plankton, it will automatically get off the boat and have a full meal. If there is no new "boat" to tie, it will stick to the reef and "rest" and wait, so it is called "free traveler".