Aplysia will use magical protective colors to protect itself. If "invisibility" is a passive method for Aplysia to avoid enemies, then Aplysia has a more active anti-enemy technique. ——Putting out "smoke bombs" and poison. In the body of Aplysia, there are special glands called purple glands, located under the edge of the mantle. When encountering an enemy, if the enemy touches the edge of the sea hare's mantle, or the sea hare is fished out of the water, the purple glands will exert their power and secrete a large amount of purple-red liquid, which will absorb the surrounding sea water. All dyed purple. This will muddy the sea water, blurring the enemy's vision and making it difficult to see the target. At this time, the sea hare can take advantage of the chaos and escape. But Aplysia moves very slowly after all. When it encounters an enemy and cannot escape, its other special gland comes into play. This gland is called a protein gland, also known as a venom gland, and is located in front of the mantle. When stimulated, the venom glands secrete a slightly acidic, milky fluid that has a very unpleasant, nauseating odor.