ИСТИНА

Clione limacina and other mollusks from the order Gymnosomata have a unique feeding structure reflecting their high food specialization - chitinous hooks. The functional role of the hooks is to grab the soft tissue of the prey (another pteropod mollusk, named Limacina) and to pull it out of the shell into the buccal cavity during the feeding. However the question of evolutionary origin of the hooks is absolutely unclear now. The buccal apparatus in many gastropod mollusks consists of the radula and the jaws. As we believe there are two possible evolutionary scenarios of the appearance of the hooks in Gymnosomata: 1) hooks evolved from the jaws 2) hooks evolved from the radula. Here we try to address this question by analyzing the neural network controlling hooks and radula movements in Clione in comparison with described in the literature neural network controlling jaws and radula movements in Aplysia, which could be considered as an ancestral form for Gymnosomata. Such an analysis brought us to conclusion that hooks in Clione most likely evolved from the radula while hook controlling neural network originated from the appropriate network of the radula in the hypothetical ancestor. Most important, that comparative-morphological study of the hooks in Clione and the jaws in Aplysia also strongly supported this idea. Thus, analyzing the neural network controlling the structure, we were able to make a conclusion on the evolutionary origin of this structure.