Stingrays are cartilaginous fish, related to sharks, found in marine and freshwater environments. Recognized by their flattened bodies, they move gracefully and are adapted for life on the seafloor, where they often conceal themselves.
The True Location and Limited Vision of Stingray Eyes
Stingray eyes are on the top (dorsal) side of their flattened bodies, differing from many fish. This placement allows them to scan for predators even when partially buried. Despite their prominent position, stingrays do not rely heavily on vision, especially when hunting, as their eyesight is poor, particularly in murky waters.
Stingray vision detects changes in light and movement rather than detailed images. Some species have a reflective layer, the tapetum lucidum, aiding low-light vision. Their eyes are typically oval and flat, and some species can retract them for protection. The protruding eyes and mouth also contribute to their hydrodynamic efficiency.
Beyond Sight: How Stingrays Truly Sense Their World
Stingrays compensate for limited vision with a suite of highly developed senses, allowing them to navigate, hunt, and detect prey.
Electroreception
A primary sensory tool is electroreception, via Ampullae of Lorenzini. These jelly-filled pores around the mouth detect weak electrical fields from other organisms, important for finding hidden prey. They also help detect predators and navigate using Earth’s magnetic field.
Chemoreception
Stingrays possess a highly developed sense of chemoreception, including smell and taste. Their nostrils (nares) are on the underside near the mouth. This acute sense of smell, making them “macrosmatic,” enables them to locate food and navigate currents.
Mechanoreception
Their mechanoreception system, the lateral line, further enhances sensory capabilities. Composed of canals and neuromasts, it detects vibrations and water pressure changes. This provides a sense of nearby movement, helping them perceive their environment and locate prey. Some species have complex lateral line systems extending into their tails, possibly functioning as a “hydrodynamic sensory antenna.”
Eyes or Spiracles? Understanding the Difference
Observers often confuse a stingray’s eyes and spiracles. Both are on the dorsal side of the head, but eyes are generally towards the front, with spiracles directly behind or slightly above.
Spiracles serve a different, important function. These specialized openings allow stingrays to draw in oxygenated water for respiration. This adaptation is important when buried in sand, as it ensures continuous water flow over gills while concealed, preventing obstruction of the mouth and ventral gill slits.