Rays are marine animals recognized for their distinctive flattened bodies and graceful movement. These cartilaginous fish, closely related to sharks, navigate diverse marine environments. Their unique adaptations allow them to thrive, leading to curiosity about their feeding mechanisms, specifically if these creatures possess teeth.
Ray Mouth Structure
Rays do not possess traditional, pointed teeth. Instead, they feature specialized dental structures known as dental plates, or pavement-like teeth. These plates are typically flat, broad, and arranged in rows within the ray’s mouth. Each individual “tooth” within these plates is a modified placoid scale (dermal denticle).
The composition of these dental plates is similar to human teeth, featuring a central cavity, dentine, and an outer enamel-like substance. These plates are continuously replaced throughout the ray’s life, much like shark teeth. New rows of teeth grow in behind the existing ones, moving forward to replace those that are worn or lost, ensuring an effective chewing surface.
How Rays Use Their Dental Plates
Ray dental plates function as powerful grinders and crushers, enabling them to process hard-shelled prey. These structures act like a mortar and pestle, allowing rays to break down the tough exoskeletons of their food through a grinding or pounding motion. The jaws of durophagous rays are rigid and supported by large jaw adductor muscles, which generate the significant force needed for crushing.
Some rays, such as the cownose ray, use specialized cephalic lobes (modified extensions of their pectoral fins) to direct prey towards their mouths. Jaw movements facilitate the winnowing process, allowing the ray to separate indigestible shell fragments from the edible soft tissues. Some male stingrays develop sharper teeth during mating season to grip the female, before their teeth return to their typical flat shape.
Ray Diet and Feeding Habits
Rays primarily feed on bottom-dwelling invertebrates. Their diet commonly includes mollusks such as clams, oysters, and mussels, as well as crustaceans like crabs and shrimp. Many rays are generalist feeders, consuming a broad range of prey, while some species have specialized dietary preferences.
To locate their buried prey on the seafloor, rays employ electroreceptors called Ampullae of Lorenzini. These organs detect weak electric fields generated by hidden organisms. After locating prey, the ray uses its ventrally located mouth to ingest and crush hard-shelled food items. Acoustic recordings have captured the distinct crunching sounds made by rays as they crush mollusk shells.