THE LOG | April 1 - April 14, 2022 | 3
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BIZARRE
By: KATHERINE M. CLEMENTS
BRITISH COLUMBIA— A study conducted
by Mike Kelly and researchers from Simon Fraser University, published by Biology Letters on March 15, uncovered the first psychological evidence that sharks take a break from the hunt to catch some zzz’s. Kelly, a comparative sleep physiologist and postdoctoral researcher at SFU’s Circadian Rhythms and Sleep Lab and Translational Neuroscience Lab, specializes in sleep among aquatic creatures, from sharks to crocodiles. His research found sharks produce a lower metabolic rate and recumbent body posture when inactive for longer than five minutes. Kelly and the other researchers observed the sharks over 24-hour periods and tracked their metabolic rates and behavior during swimming, resting, and suspected sleep periods. “The sharks showed a dramatic decrease in their metabolic rate and an obvious postural change following five minutes of inactivity, which demonstrated a distinct separation between periods of quiet wakefulness and sleep,” said Kelly in the study. It is widely understood that ani-
mals sleep, including bony fish species. However, Kelly says the resea rch pro vides the first physiological evidence of sleep among elasmobranchs, a group including sharks, rays, and skates. Kelly earlier studied sleep behavior among crocodiles for his Honors thesis at Australia’s La Trobe University. The research found these creatures likely slept with one eye open and was later published in the Journal of Experimental Biology. In a dd it ion t o sleep research with sharks, Kelly has be- Some sharks must swim constantly during sleep to keep oxygen-filled water flowing over their gills. This come fluent in the fact leans towards sharks being closer to resting than sleeping. circadian rhy thms and sleep behavior of many other fish species and has extend“I find the best way to overcome my said Kelly. “Besides, better to be around ed his work to include related behaviors sheer terror of these creatures of the deep them when they’re sleeping than when in octopuses. is to get up close and personal with them,” they’re ready to feed!”
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Eat, Sleep, Shark, Repeat
