Manta rays, with their impressive wing-like fins and gentle demeanor, are among the ocean’s most captivating inhabitants. Their graceful movements beneath the waves often spark curiosity about whether these large cartilaginous fish are active throughout the day or night.
Manta Ray Activity Patterns
Manta rays are primarily active during the day, making them diurnal creatures. They also exhibit heightened activity during dawn and dusk, a pattern known as crepuscular behavior. Observations indicate manta rays spend most of their time in surface waters during daylight hours, often in the upper 60 meters, before descending as evening approaches. Crepuscular activity refers to peaks during the twilight periods of dawn and dusk.
Daytime Activities
During their active periods, manta rays engage in several key behaviors, primarily feeding. They are filter feeders, consuming plankton and occasionally small fish or shrimp. Manta rays employ various feeding strategies, such as ram feeding (swimming with their mouths open to sieve plankton) or cooperative behaviors like chain feeding, where multiple rays align to create a large collective mouth. In areas with dense plankton, they may perform barrel rolls or somersaults to efficiently feed in one spot.
Another daytime activity is visiting cleaning stations, reef areas where smaller fish, such as wrasses and gobies, remove parasites and dead skin. This symbiotic relationship benefits the manta’s health and provides food for the cleaner fish. Manta rays often hover or swim slowly in circles at these stations. Though often solitary, manta rays also form social groups and exhibit preferred social partners, particularly at feeding and cleaning sites.
Nighttime Behavior
As darkness falls, manta rays reduce their activity. While they can feed at any time, much of their foraging often occurs at night when plankton rise closer to the surface. During these periods, they may move to deeper waters or find sheltered areas to rest.
Manta rays do not sleep in a traditional sense, as they need to keep moving to push oxygen-rich water over their gills for breathing. Instead, they exhibit a form of rest called unihemispheric sleep, where one half of their brain rests while the other remains alert. They might swim slowly, hover near reefs, or even adopt vertical postures during these resting phases. Notably, in some locations like Hawaii, artificial lights attract plankton at night, drawing manta rays to these illuminated sites for feeding, creating nighttime viewing opportunities.