How slug becoming self defence?

Biologists have discovered why the sea slug (scientific name aplysia) always leaves a smudge on the surface where they have crawled. It turns out that nature has taught them to do so to paralyze the ability of the enemies to eat themselves.

The conclusion of this study by scientists from the University of Georgia (USA) was published in the journal Experimental Biology.

The mucus released by the sea slug is to prevent the enemy from pursuing them.

Sea slug is a mollusk in the snail family, but in the process of evolution, they lose the hard shell that covers the outside. When attacked by predators, like cuttlefish, they spray water with a dark purple liquid to camouflage, causing the enemy to "darken" them, not recognizing themselves and then fleeing. But before, biologists still did not understand what mucus they left behind when the cow passed.

To understand this secret biologists have done many experiments with lobster as one of the natural enemies of the sea slug, searching for them to eat. They extracted the mucus of the nudibranch (called opalin because it is a milky color) applied to lobster beard and then released both opponents (including unpolluted lobsters on the beard to control) into the tank to observe.

After measuring the electrical activity of neurons in charge of lobster sensing and movement, scientists found that the lobsters that had been smeared with opalin on their whiskers did not recognize their prey, always let them escape, while the controls were still swiftly eating meat.

Researchers believe that both purple liquid and opalin mucus produced by different routes are used by sea slugs as a defense weapon.'The color used in more dangerous situations like being eaten by carnivores is about to (or already) catch, and the mucus is just a precaution,' said Charles Derby, one of the authors of the article.