An Alligator's Sixth Sense

Devil's BSD writes "NPR has this article about how alligators sense their prey. Apparently, those black dots on a alligator are really "dome pressure receptors", which alligators use to detect changes in water pressure caused by ripples in the water. The alligator then does some fancy triangulation, and can then detect precisely where its prey is."

Comments

Get the Doctors site here.

[satanami69]

http://www.wam.umd.edu/~daph/DPR.html
They have some movies in .qt format showing the gators attacking drops of water.

Sixth Sense?

[alnapp]

I see Handbags, all the time

Boggled alligators

[guacamolefoo]

My one question about this whole theory is what do the alligators do when it rains (other than get wet)? I imagine there must be some sort of way to cut down on the feedback/nerve responses. Also, when they swim, it seems that the pressure receptors would boggle the alligator.

Re:Boggled alligators

[Nos.]

The article I read a day or two ago (on CBC's website compared it to the human ear. Our ear works basically the same way as these sensors. When there's a lot of noise, it tends to be ignored, but you can still pick out differences. My guess would be that the first few drops may get the gator's attention, but after that it would become background "noise". However, an animal splashing around would proably make bigger waves, and thus be more noticeable.

Not Hogwash

[crow]

It's not hogwash at all. Sure, reptile brains may be simple in many ways, but that's not relevant. You don't have to be able to perform advanced trigonometry and calculus to figure out the trajectory of a thrown ball so that you can catch it. Instead, you get a sense for where the ball is going based on having seen balls thrown before.

Likewise, the alligator simply notices that certain patterns of pressure changes indicate that there is something in the water in a given direction.

Sure, you can describe what is going on with advanced mathematics, but the actual application is done with simple pattern matching.

Other senses

[crow]

I remember watching a show, probably on the Discovery Channel, about how many animals have weird senses. For example, some birds apparently see a spot at magnetic north and can use that for navigation. Turtles have some similar sense that they also use for navigation.

And we all know bats use sonar.

What other senses do animals have that we lack?

Re:Other senses

[rusty0101]

Bees sense polarization of light, As a result the sky is their map.

Ears?

[zpengo]

Apparently, those black dots on a alligator are really "dome pressure receptors", which alligators use to detect changes in water pressure caused by ripples in the water. The alligator then does some fancy triangulation, and can then detect precisely where its prey is."

Perhaps I'm mistaken, but isn't that essentially what ears do?

Re:Ears?

[diesel_jackass]

Last time i checked that's what my ears do. Except you can't triangulate with only 2 points, but your brain uses other cues to determine where the sound is located.

I'm curious about this "fancy triangulation" though. Does it use a graphing calculator or what?

Re:Ears?

[blankmange]

Slide rule for the older crocs and younger crocs pull out a PDA and do the figures that way....

Re:Ears?

[Fat Casper]

Except you can't triangulate with only 2 points,

When was the last time you saw a triangle? The 2 points of your ears can tell you where the third point is. They're a little close together, and pointing in opposite directions, so they're less accurate than your eyes, but they still do a pretty good job.

Re:Ears?

[diesel_jackass]

well, lets go through an example together, ok?
your left ear hears a sound that's 2 feet away. all points 2 feet away will make a sphere around this ear (with a radius of 2 feet).
your left ear hears a sound 1 foot away. all points from this ear makes a sphere around it (with a radius of 1 foot).
all points where these 2 spheres intersect form a circle.
your brain uses many clues to locate the sound on this circle. two of the ways that it does this is if you move (by turning your head or whatever) or the sound moves. usually your brain just locates it from memory (certain sounds come from certain objects, certain voices come from certain people, etc.)
when you think in three dimensions, it doesn't really look like a triangle. i'm not exactly an expert in this area (i did take psychology of perception in college), so feel free to prove me wrong. ;-)

Re:Ears?

[rehannan]

You're sort of right. The weird shape of your outer ear also plays a very large role in determining where a sound came from.

How Hearing Works

Got to say it

[macdaddy]

Can you imagine a cluster of these? I have a feeling it would resemble the store window of an exotic accessory store: boots, bags, hat bands.... :)

Re:Got to say it

[Sanga]

--
I used to have a cool sig but people replied to it more than they did my comments.

Tell me about it :)

Some humans can - haidinger's brushes.

[TheLink]

Do google search on Haidinger's brushes.

http://world.std.com/~mmcirvin/haidinger.html

http://www.dur.ac.uk/~dph0rms/opticsII/notes/lec tu re-notes/node17.html