in taxon Mollusca organism subdivision visceral hump visceral sac UBERON:0008937 Mollusks have three distinct divisions of their body. The head contains the sensory equipment (eyes, antennae, etc) and the primitive brain. The visceral hump, which is the main body, contains most of the organs, including a complete digestive and excretory tract as well as the reproductive organs. The visceral hump also includes the two external flaps of tissue, which are known as the mantle. BTO:0001448