Sensory systems
Among chondrichthyan species there are at least eight well- developed sensory systems, several of which are formed from highly sensory cells that can discharge an electrical impulse
to a comparatively large brain. The paired eyes provide for an excellent field of vision and the retina has colour-distinguishing cone photo-receptor cells and low-light sensitive rod photo- receptor cells. Another adaptation to low-light conditions is the presence behind the retina of the tapetum lucidum consisting of mirror-like crystals. An acute sense of smell is provided by two olfactory sacs under the snout associated
with the large front section of the brain (olfactory lobes).