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The jaw is opposite to the radula and reinforces part of the foregut. [2] The more purely carnivorous the diet, the more the jaw is reduced. [2] There are often pieces of food in the gut corresponding to the shape of the jaw. [2] The jaw structure can be ribbed or smooth:
In opisthobranch marine gastropods, the chemosensory organs are two protruding structures on top of the head. These are known as rhinophores . An opisthobranch sea slug Navanax inermis has chemoreceptors on the sides of its mouth to track mucopolysaccharides in the slime trails of prey, and of potential mates.
The columella (meaning "little column") or (in older texts) pillar is a central anatomical feature of a coiled snail shell, a gastropod shell. The columella is often only clearly visible as a structure when the shell is broken, sliced in half vertically, or viewed as an X-ray image.
Shell of marine snail Lunella torquata with the calcareous operculum in place Gastropod shell of the freshwater snail Viviparus contectus with corneous operculum in place. An operculum (Latin for 'cover, covering'; pl. opercula or operculums) is a corneous or calcareous anatomical structure like a trapdoor that exists in many (but not all) groups of sea snails and freshwater snails, and also ...
The anatomy of a common air-breathing land snail: much of this anatomy does not apply to gastropods in other clades or groups. Snails are distinguished by an anatomical process known as torsion, where the visceral mass of the animal rotates 180° to one side during development, such that the anus is situated more or less above the head. This ...
The snail's oesophageal gland houses symbiotic gammaproteobacteria from which the snail appears to obtain its nourishment. This species is considered to be one of the most peculiar deep-sea hydrothermal-vent gastropods, and it is the only known extant animal that incorporates iron sulfide into its skeleton (into both its sclerites and into its ...
Its head anatomy provided evidence that millipedes and centipedes are more closely related than previously thought. ... The shape of its feeding appendages and position of the jaws are centipede ...
The outermost layer is the periostracum which is resistant to abrasion and provides most shell coloration. The body of the snail contacts the innermost smooth layer that may be composed of mother-of-pearl or shell nacre, a dense horizontally packed form of conchiolin, which is layered upon the periostracum as the snail grows. [citation needed]