Manta rays are captivating ocean inhabitants, gliding gracefully through tropical and subtropical waters worldwide. Known for their immense size, some individuals reach up to 9 meters (30 feet) in width. Their fluid movements make them a remarkable sight. They inhabit a wide range of environments, from coastal reefs to open oceanic waters.
The Jaw Question Answered
Despite their large size and relation to sharks, manta rays do not possess traditional biting jaws like many predatory fish. Their mouth structure is uniquely adapted for a specialized feeding method. While they have small, peg-like teeth on their lower jaw, these are not used for chewing or biting. These teeth are considered vestigial remnants from their evolutionary past, highlighting their unique adaptation.
How Manta Rays Feed
Manta rays are filter feeders, consuming vast quantities of tiny organisms suspended in the water. They achieve this by swimming with their wide mouths open, allowing large volumes of seawater to pass through. Their diet primarily consists of microscopic zooplankton, including copepods, mysid shrimp, crab larvae, and fish eggs. They do not actively suck in food but rather swim continuously through plankton-rich waters to filter their meals.
These rays are efficient feeders, capable of consuming up to 13 percent of their body weight per week, or 20 to 30 kilograms (44 to 66 pounds) daily. To maximize intake, manta rays employ various strategies. These include straight feeding through plankton patches, or surface feeding where they skim the water. They also engage in coordinated behaviors like chain feeding, where multiple rays line up, or cyclone feeding, forming a spiraling vortex to concentrate prey.
Anatomy of Their Mouth
The manta ray’s mouth is distinctively large and positioned at the front of its broad, flattened head. This terminal mouth contrasts with many other rays, which typically have mouths on their underside. Flanking their mouths are two prominent, paddle-like cephalic lobes, modified extensions of their pectoral fins. These flexible lobes unroll and extend forward, acting like funnels to direct plankton-rich water into their oral cavity.
Inside the mouth, manta rays possess specialized gill rakers. These are rows of leaf-like, cartilaginous projections on their gill arches. As water flows over these rakers, they filter out tiny food particles while allowing water to exit through five pairs of gill slits. This efficient filtering mechanism prevents clogging and captures even very small particles. The cephalic lobes also aid in sensing the environment and facilitating social communication.
Gentle Giants of the Sea
Manta rays are widely recognized for their docile nature and pose no threat to humans. Unlike their relatives, stingrays, manta rays do not possess a venomous barb or stinger on their tail. Their primary diet of microscopic plankton means they have no need for large teeth or aggressive predatory behaviors.
Their calm demeanor and curiosity often lead them to approach divers and snorkelers. Manta rays rely on their immense size and agile swimming to deter predators, rather than any defensive weaponry.