What are the main traits characterizing molluscs?

| September 23, 2021 | education

1) soft-bodied.
2) bilateral symmetry (except gastropods).
3) the body is protected by a shell (except for cephalopods and slugs).
4) the body is covered with a mantle-skin fold hanging from the back; there is a mantle cavity.
5) secondary body cavity.
6) the body is not segmented, 3 sections: head, trunk, leg.
7) the circulatory system is open, the heart is on the dorsal side.
8) digestive system: mouth-pharynx-esophagus-stomach-intestines-anus; there are salivary glands and a grater; a liver appears.
9) respiratory organs – gills or lungs.
10) excretory organs – kidneys.
11) the nervous system is scattered-nodular; the sense organs are well developed; sexual reproduction; most often mollusks. dioecious; fertilization is external; development is direct and indirect.



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