Shark Senses
With an evolutionary period of over 400 million years, sharks are finely tuned to their environment. Sharks have a total of seven senses to interpret changes in their environment. These senses are: auditory perception (sound), tactician (touch), gustatory perception (taste), vision (sight), olfaction (taste), water movement detection (lateral line) and electro/magnetic reception. These senses are used for prey detection, orientation, and predator avoidance
White Shark Vision
Vision is vital for most sharks particularly when hunting fast-moving prey in varying light levels. Eye size and visual ability varies from species to species depending on habitat use and feeding behaviours. The White shark has well-developed eyes with large areas of the brain dedicated to vision suggesting that vision is important. White sharks occupy many habitats, from deep low light environments to shallow reefs where light is abundant. Therefore adaptive vision is an important adaptation and laterally positioned eyes allow a large field of vision both horizontally and vertically. White sharks also have reflective layer known as tapetum lucidum which enhances vision at low light levels.
Presence of a duplex retina containing both rods and cones is common in many shark species. A duplex retina suggests the basis for good vision in a variety of light conditions. However, White sharks show variation in rod to cone receptors around the retina with increased cone density in the centre of the retina and no cones in the periphery, suggesting the central retina is used for day vision and the periphery is most effective at night or in low light levels, such as in deep water. However, most sharks studied have cone monochromacy which likely means that they have poor or no colour vision (Hart et al. 2011), this visual perception is commonly seen throughout marine mammal species such as pinnipeds and cetaceans.
0 Comments