Crazy Nurse Shark

[Rollin Bonz]

Neat...I wish I could get rid of parasites that way.

You just won ScubaBoard!

Actually, I think @divad did LOL

 

[falcon125]

It would appear the shark is swimming.

 

[wsr523]

It would appear the shark is swimming.

Swimming erratically maybe...haha

 

[Hank49]

Turning sharks onto their back makes them pass out?. Maybe this one was just getting high and rolling back over before he blacked out.

 

[RyanT]

Turning sharks onto their back makes them pass out?. Maybe this one was just getting high and rolling back over before he blacked out.

This is referred to as "tonic immobility." It occurs when sharks, that normally swim at midwater depths, are turned upside down. Virtually all vertebrate animals retain an orientation in the world based on the information their sensory systems give them. If you take a shark that normally swims in the water column, and uses the sun as one of it's sensory cues, and turn it upside down, then its sensory systems no longer provide the correct information to the animal. Gravity is pulling on the sensory organs in the opposite direction, the sun is in the wrong position, etc. So the animal becomes disoriented and goes limp. For a nurse shark, whose world exists on the bottom, the bottom provides a visual and tactile cue for orientation. So rolling upside down isn't a big deal because they are able to orient to the bottom and tonic immobility isn't such an issue.

The nurse shark in the video was almost certainly scratching parasites.

 

[Hank49]

This is referred to as "tonic immobility." It occurs when sharks, that normally swim at midwater depths, are turned upside down. Virtually all vertebrate animals retain an orientation in the world based on the information their sensory systems give them. If you take a shark that normally swims in the water column, and uses the sun as one of it's sensory cues, and turn it upside down, then its sensory systems no longer provide the correct information to the animal. Gravity is pulling on the sensory organs in the opposite direction, the sun is in the wrong position, etc. So the animal becomes disoriented and goes limp. For a nurse shark, whose world exists on the bottom, the bottom provides a visual and tactile cue for orientation. So rolling upside down isn't a big deal because they are able to orient to the bottom and tonic immobility isn't such an issue.

The nurse shark in the video was almost certainly scratching parasites.

I was joking.

 

[RyanT]

I was joking

Doh! Apparently my humor filter was inadvertently turned up too high.

 

[wsr523]

This is referred to as "tonic immobility." It occurs when sharks, that normally swim at midwater depths, are turned upside down. Virtually all vertebrate animals retain an orientation in the world based on the information their sensory systems give them. If you take a shark that normally swims in the water column, and uses the sun as one of it's sensory cues, and turn it upside down, then its sensory systems no longer provide the correct information to the animal. Gravity is pulling on the sensory organs in the opposite direction, the sun is in the wrong position, etc. So the animal becomes disoriented and goes limp. For a nurse shark, whose world exists on the bottom, the bottom provides a visual and tactile cue for orientation. So rolling upside down isn't a big deal because they are able to orient to the bottom and tonic immobility isn't such an issue.

The nurse shark in the video was almost certainly scratching parasites.

When I was recording the nurse shark my first thoughts were hey, I thought sharks couldnt be on their backs like that. Thanks for the excellent explanation!

 

[CT-Rich]

Neat...I wish I could get rid of parasites that way.

Yeah, this voting thing just seems to make the parasites worse....

 

[ystrout]

Scratching. Sometimes external parasites or their skin just itches for whatever reason. Every once in a while, I'll see one of my pet fish do it even though none of them have parasites or anything.

You'll frequently see many fish do it on rocks, bouy lines, etc.