s of
Aplysia californica. s on the head of the edible snail
Helix pomatia have eyes, but the main sensory organs are sensory neurons for
olfaction in the
epithelium of the tentacles. In terrestrial gastropods the most important sensory organs are the olfactory organs which are located on the tips of the 4
tentacles. 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
freshwater snail Bithynia tentaculata is capable of detecting the presence of molluscivorous (mollusk-eating)
leeches through
chemoreception, and of closing its
operculum to avoid predation. The deepwater snail
Bathynerita naticoidea can detect mussel beds containing the mussel
Bathymodiolus childressi, because it is attracted to water that has cues in it from this species of mussel. == Eyes == In terrestrial pulmonate gastropods, eye spots are present at the tips of the tentacles in the
Stylommatophora or at the base of the tentacles in the
Basommatophora. These eye spots range from simple
ocelli that cannot project an image (simply distinguishing light and dark), to more complex pit and even lens eyes. Vision is not the most important requirement in terrestrial gastropods, because they are mainly nocturnal animals. and marine species of genus
Strombus can completely
regenerate their eyes. The gastropods in both of these families have lens eyes. Morphological sequence of different types of multicellular eyes exemplified by gastropod eyes:
Lens eyes another drawing of eye of
Helix pomatia == Statocysts ==