Rays are marine creatures known for their unique appearance, easily distinguishable. Their distinctive flattened bodies and graceful movement are characteristic. These animals are cartilaginous fishes, sharing a close evolutionary relationship with sharks.
General Body Plan
The most prominent feature of a ray is its dorsoventrally flattened body, giving it a disc-like or diamond shape. Their body plan allows them to glide along the seafloor. Greatly enlarged pectoral fins are seamlessly fused to the sides of their head, creating their broad, flattened form.
These wing-like pectoral fins serve as their primary means of propulsion, enabling them to move through water with undulating or flapping motions. Their swimming style, combined with their flattened body, contributes to efficient movement. They often blend into the bottom terrain.
Distinctive Features of the Head and Underside
Their eyes are typically positioned on the top surface of their head, providing an upward view. Behind the eyes are large openings called spiracles, which allow rays to draw in water for respiration, especially when partially buried in sand.
Their mouth, nostrils, and gill slits are located on their flattened underside. Rays typically possess five pairs of gill slits situated ventrally. Ventral placement distinguishes them from sharks, whose gill slits are located on the sides of their heads.
The Tail: A Defining Element
A ray’s tail varies considerably among different species. Many rays possess a long, slender, whip-like tail. This tail may or may not be equipped with one or more sharp, venomous spines or barbs, particularly in stingrays. These spines are primarily used for defense, not for hunting.
Some ray species, such as electric rays, have a shorter and stouter tail. Many ray species also lack a prominent caudal (tail) fin, which differentiates them from sharks, which typically have well-developed caudal fins for propulsion. Tail structure and presence or absence of defensive spines contribute to the ray’s overall look.
Variations in Appearance
Rays exhibit a wide range of appearances, reflecting diverse adaptations. Their size can vary greatly, from small species with wingspans of around 30 centimeters to enormous manta rays that can reach over 6.1 meters (20 feet) in wingspan. These size differences are often linked to their habitats and feeding strategies.
Skin textures also differ, ranging from smooth to rough or thorny. Some species possess spiny or thorn-like structures on their upper surface. Coloration patterns vary widely, including spots, stripes, and mottled designs, which aid in camouflage against the seafloor. Some rays can even change their color over several days to adapt to new surroundings.