They are neither. Blue whales do not actually sleep, although they take very deep forms of naps.
They have to surface to breathe, so they cannot stay underwater for more than about 30 minutes. To compensate, whales can rest just the cognitive parts of their brains, while keeping their automatic swimming and breathing routines active.
The answer is both. Narwhals don't care whether it is light out or dark out when they wake up. Based on their sonar hearing and their sensitivity to light, they don't have to take much precaution when waking up.
Beluga whales are diurnal.
They do use the hemispheric slow wave sleep technique though; half of their brains shut off while the other half stays awake, searching for predators or sound waves and warnings from pod mates. They don't use this all the time though, they do stay fully aware and only have to do this after every four hours. When they fully rest, they float on top of the water with the rest of their group.
Don't you pay any attention during science
anyway they are diurnal
diurnal
Blue whales are neither nocturnal nor diurnal. These mammals take 30-minute cat naps throughout the day and cannot sleep longer than this time frame.
Killer whales are diurnal. They are most active during the day time, with each Pod having its own unique daily cycle/routine.
Jaguarudi's are both nocturnal and diurnal.
The term opposite of nocturnal is "diurnal." (active mostly during the day).The opposite of nocturnal is diurnal.
The West Indian Manatee is diurnal it is not nocturnal.
Dingos can be both nocturnal and diurnal. Whether they are nocturnal or diurnal, usually depends on the climate where the dingo lives.
diurnal.
Diurnal
Diurnal diurnal
diurnal
diurnal
Diurnal.