If Manatees Can Hear Boats, Why Don't They Move When One's Coming?

Categories: Environment
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ScienceDaily
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.

A new study suggests, however, that manatees seem perfectly capable of hearing oncoming boats above background noise. So why don't they move when a boat is tearing through the water toward them? 

"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. 

The study, published in The Journal of Experimental Biology, demonstrates just how freaking awesome these animals are. First off, the names of the two manatees used in the study were Buffett and Hugh; talk about a code-red cute alert. 

The two were trained to "touch a yellow response panel in exchange for a tasty fruit or vegetable snack when they heard a sound" emitted from a station about a meter under water. 

So what level of noise can they hear?

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. 

That's a lengthy way of saying these slow-moving fatsos should be able to hear boats coming -- so long as they're not distracted by being lazy (sleeping or eating). 

At one point in the study, Buffett proved capable of hearing "ultrasonic frequencies" but apparently became agitated by the sound and refused to show off this skill a second time. 

What a diva.

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6 comments
FQS9000
FQS9000

Manatees are as dumb as Democraps and thus are too stupid to move when they hear a boat coming.

Manatee lover
Manatee lover

Well, these two better stay in captivity, now that they've been trained to GO TO THE NOISE.

Chris Sweeney
Chris Sweeney

Hey, good point about whether they can discern which direction sounds are coming from. Apparently, they can, according to a team of researchers from various S. Florida universities who published a study in 2009 on the subject. Here's what they wrote in a press statement about that study: Having trained the manatees to swim to the speaker that they thought the sound came from, the team then played the broadband sounds, of 0.2, 0.5, 1 to 3s, from each speaker at random while monitoring the animals' responses. One of the manatees, Buffett, successfully identified the source of the broadband sounds with almost 90% accuracy, while Hugh did slightly less well. The team was also surprised that the manatees were able to locate the sources of both the 4kHz and 16kHz tones, although the team only tested the animals with the longest of the two tonal notes, as the animals had shown signs of frustration when they heard these sounds.

Chris Sweeney
Chris Sweeney

Hey - good point about the direction aspect. A few years back, researchers from a few S. Florida universities published a study indicating that manatees are capable of discerning what direction sounds are coming from. 

They wrote in a PR for the study: "Having trained the manatees to swim to the speaker that they thought the sound came from, the team then played the broadband sounds, of 0.2, 0.5, 1 to 3s, from each speaker at random while monitoring the animals' responses.One of the manatees, Buffett, successfully identified the source of the broadband sounds with almost 90% accuracy, while Hugh did slightly less well. The team was also surprised that the manatees were able to locate the sources of both the 4kHz and 16kHz tones, although the team only tested the animals with the longest of the two tonal notes, as the animals had shown signs of frustration when they heard these sounds."

Here's a link to the study summary: http://www.sciencedaily.com/re...

Will let you know about funding when I hear back. 

Hearear
Hearear

I hear pretty good but can't tell what direction or how close a boat is coming.  I can sort of hear it getting closer because it gets louder. 

I imagine manatees are about the same.  

-how much did this study cost?

JB
JB

That has nothing to do with the story. Try an anti-depressant or smoke something.

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