SeaMonster at Dubai Aquarium and Underwater Zoo?

[RyanT]

Hi Chris:
Here's a screen shot. You can see two of them laying on the bottom. One is right next to the wreck and the other in the lower right hand corner. There was no discernible current, so they weren't siting, oriented into current. We seem them do this all the time here off NC in the US.

 

[chris kippax]

Hi Chris:
Here's a screen shot. You can see two of them laying on the bottom. One is right next to the wreck and the other in the lower right hand corner. There was no discernible current, so they weren't siting, oriented into current. We seem them do this all the time here off NC in the US.View attachment 654040

Thanks Ryan, that is super interesting! I wonder if any one has ever studied it?
It may be a learned behaviour from spending so much time in the wrecks there buccal breathing technique is super strong???
I wonder if this behaviour is endemic to the NC wreck sand tigers???

 

[Raphus]

I did some reading as well, because I was sure I saw videos of them on them bottom.

So as far as I know, they sleep while hovering, not swimming. Which is very interesting, they "eat" the right amount of air to be neutral buoyant.
But as most(all?) sharks, they have no swimming bladder. So if they don't but air in their stomach they sink. That's why they sometimes lie on the bottom.

Ether way, they can breath actively, so I guess we were all right
The truth was somewhere between.

Very interesting animal. Sadly never saw one in real life yet.

 

[RyanT]

http://www.int-res.com/articles/esr2015/27/n027p069.pdf

https://www.mass.gov/files/document...t_al-2018-Environmental_Biology_of_Fishes.pdf

Hi Chris, yes, it has been studied, but not necessarily in depth. Here's links to two studies that report non-activity/buccal pumping. One study was from Australia, so it doesn't appear to be an endemic behavior.

 

[chris kippax]

http://www.int-res.com/articles/esr2015/27/n027p069.pdf

https://www.mass.gov/files/document...t_al-2018-Environmental_Biology_of_Fishes.pdf

Hi Chris, yes, it has been studied, but not necessarily in depth. Here's links to two studies that report non-activity/buccal pumping. One study was from Australia, so it doesn't appear to be an endemic behavior.

Thanks Ryan, very interesting read's.
I stand corrected on the US sharks and appreciate your input & patience, in the East Coast Australian paper I see no reference to resting on the bottom?? I just see the three categories of Milling,hovering & swimming
Regardless these are cool sharks that are quite a bit outside the norm.

 

[chris kippax]

Another thing I find super interesting is the US sand tigers love for wrecks.
In Australia we have a large ex warship only a few miles from a known Grey Nurse aggregation site yet they are super rare to be seen anywhere near the wreck? The wreck has a tonne of food on it and heaps of shelter.
Obviously the NC wrecks have been down for 80 odd years where ours was scuttled maybe 12 or so years ago.
Were the sharks on the NC wrecks when rec scuba began diving them or did they increase as the years went on?

 

[RyanT]

Hi Chris: No problem. I gave the Australian paper a quick perusal, and it looks like you are correct. I saw that the authors reported buccal pumping, but they didn't expressly state that the sharks were laying on the bottom. They very well could have been hovering in midwater, while buccal pumping. It does demonstrate that the sharks can lie motionless on the bottom. But the authors not reporting that, makes me think they were just hovering in the water column. Maybe laying on the bottom is a North American thing. I think the Australian paper also mentioned bottom topography. Where we see them on the bottom is flat sand. So maybe a distribution thing? Bottom topography thing? Now my interest is piqued!

 

[RyanT]

Were the sharks on the NC wrecks when rec scuba began diving them or did they increase as the years went on?

That I don't know. I can tell you that here in North America, they aren't simply attracted to wrecks. They are commonly caught off the beaches by fishermen here in the mid-Atlantic region over sandy bottoms. I guessing the NC wrecks being popular among divers makes it seem like they are just found around wrecks!

 

[RyanT]

I should have finished my thought in the previous post....Yes, it is an interesting question as to why they aggregate so densely around the NC wrecks. There is a group who is working on documenting movement patterns of individual sharks on the NC wrecks. Here's the link.

Spot A Shark USA - Engaging citizen scientists in sand tiger shark research

 

[Pressurehead]

I think the wreck Chris is talking about [I know it well] is so busy with divers they avoid the area, this is during the day and early night when the local dive boats take divers out, just a thought.
A dive after midnight could be another story.
As Chris said there are plenty of fish on this wreck.

Another thing I find super interesting is the US sand tigers love for wrecks.
In Australia we have a large ex warship only a few miles from a known Grey Nurse aggregation site yet they are super rare to be seen anywhere near the wreck? The wreck has a tonne of food on it and heaps of shelter.
Obviously the NC wrecks have been down for 80 odd years where ours was scuttled maybe 12 or so years ago.
Were the sharks on the NC wrecks when rec scuba began diving them or did they increase as the years went on?

That I don't know. I can tell you that here in North America, they aren't simply attracted to wrecks. They are commonly caught off the beaches by fishermen here in the mid-Atlantic region over sandy bottoms. I guessing the NC wrecks being popular among divers makes it seem like they are just found around wrecks!