According to the LA Times, researchers from the National Marine Mammal Foundation in San Diego, California have discovered yet another remarkable fact about dolphins. Not only do dolphins manage to stay awake, but they do so without the aid of caffeine or Red Bull— an enviable trait.
A dolphin’s ability to keep one hemisphere of their brain awake while the other sleeps allows them to remain alert for two weeks straight. In a study published Wednesday in the journal PLoS ONE, researchers determined that breathing underwater was not the only reason dolphins needed to rest only half their brain at a time. In fact, the new research suggests that the detection of predators is equally important.
“In dolphins, natural selection has developed unihemispheric sleep where alternating hemispheres of their brain stay awake. This allows dolphins to maintain consciousness in response to respiratory demands of the ocean,” the authors write in the abstract. “Unihemispheric sleep may also allow dolphins to maintain vigilant states over long periods of time.”
In order to explore a dolphin’s ability to stay alert, researchers from the National Marine Mammal Foundation tested both a male and a female dolphin. Using their sound-based navigation system—called echolocation, which functions similarly to sonar— the dolphins were required to find randomly dispersed targets throughout their enclosure. Once these targets were located, the dolphins were taught to bump a paddle at the end of their research pen. When they were correct, they received auditory feedback and a fish as a treat.
Research revealed that the dolphins were exceptionally good at the task, with the female responding correctly over 90 percent of the time and the male over 75 percent. After five days straight, the dolphin’s performance waned only slightly. In fact, the female dolphin was able to endure the test for 15 days straight without a decrease in performance.
“A 15-day testing session with one dolphin resulted in near perfect performance with no significant decrement over time,” the authors add. “Our results demonstrate that dolphins can continuously monitor their environment and maintain long-term vigilant behavior through echolocation.”
The added alertness for the species certainly increased the creature’s awareness of predators, and, perhaps, even prey. By allowing only one hemisphere of the brain to rest at a time, just think what our own species could accomplish. Until we develop such abilities, we can at least remain impressed with the abilities of these amazing ocean-bound mammals.
“If dolphins sleep like terrestrial animals, they might drown. If dolphins fail to maintain vigilance, they become susceptible to predation,” the authors conclude. “As a result, the apparent ‘extreme’ capabilities these animals possess are likely to be quite normal, unspectacular, and necessary for survival from the dolphin’s perspective.”
National Geographic notes that limited dolphin fishing occurs today but that the main threat to the species is commercial fishing for other species, like tuna. Dolphins can become mortally entangled in nets and other fishing equipment due to their curious nature.