Rest and activity states in a gray whale

Area of Science:

• Marine Mammal Behavior
• Cetacean Sleep Studies
• Animal Neurology

Background:

• Understanding cetacean behavior is crucial for conservation efforts.
• Previous research on gray whale sleep is limited, especially in captive individuals.

Purpose of the Study:

• To document and analyze the behavior of a rescued female gray whale over a nine-day period.
• To investigate the characteristics of rest and potential sleep states in this individual.

Main Methods:

• Continuous video recording of a female gray whale at Sea World, San Diego for 9 days.
• Behavioral analysis categorizing activity into wakefulness, transitional stages, and rest.
• Detailed observation of physical movements, eye state, and specific jerking phenomena during rest.

Main Results:

• The whale spent approximately 41.2% of its time in a rest state, divided between lying on the bottom and hanging at the surface.
• During rest, the whale exhibited immobility punctuated by respiratory movements, varied eye closure patterns, and characteristic head/body jerks.
• Intense jerking episodes, resembling mammalian paradoxical sleep twitches, were observed, sometimes preceding slow rolls and swimming initiation.

Conclusions:

• The observed jerking behaviors during rest in the gray whale share similarities with paradoxical sleep phenomena in terrestrial mammals.
• These findings suggest complex neurological states during rest in cetaceans.
• Further research is needed to confirm the nature of these behaviors and their relation to sleep architecture in marine mammals.