If Manatees Can Hear Boats, Why Don't They Move When One's Coming?
Last week, Sea World took in an approximately 1,700-pound manatee that had been bashed up by a speeding boat. It's the seventh sea cow taken in by the facility this year alone, and regulations to stop boats from hitting the sweet morons have been debated, sort of.
"Manatees might be less aware of these sounds when they are sleeping, eating, or performing other activities related to their daily life," study co-author Joe Gaspard of the Mote Marine Laboratory and Aquarium said in a news release. Given their looks, it's safe to assume manatees are sleeping or eating 99 percent of the time.
Once Hugh and Buffett had got the task in hand, the team tested their hearing by selecting a particular sound frequency (pitch) and gradually lowering the volume of the sound until the manatee could no longer hear it. Plotting these "hearing thresholds" on a graph, the team could see that the manatees had good hearing between 8 and 32kHz and could even hear sounds as low as 0.25kHz -- so long as they were quite loud.
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