Grey Smoothound Shark Behavior

Anyone know why these sharks swim at the top of the water with the tip of their nose out?
You can see what Im saying here in the back on the tank in this video at 1:55
http://youtu.be/BNDJ3F9i3PQ

I own one and work at a large wholesaler and noticed this behavior in our tanks, my home tank, and online in other videos. I noticed an old thread where someone mentioned this as being normal including zoo diver. Anyone have any more insight into this behavior?

Here is some other notable behavior. Smoothound Surfing.

[video=youtube_share;AV6E6HpfbKA]http://youtu.be/AV6E6HpfbKA[/video]

Two 1300 GPH Power Heads in Tank
1000 GPH Overflow Box
850 GPH coming out the return
500 GPH Canister For Water Polishing
500 GPH Powerhead in Sump.

Zoodiver said:

Couple of thoughts/questions:
Looks like California Horn sharks in there as well, so is it a cool/cold water system?
Looks like several sharks in there without many places to hide/relax. I'd try making some type of area for the horns to rest in.
What else is tied into the system? I see egg crate dividers, and it looks like other fish on the other side. My thought is that something else in the system is triggering an active behavior like this. Maybe a hormone release of some type (like a stress hormone) that is spiking activity in the sharks.

Click to expand...

The first video with the horn sharks was a video I found from a LFS in California.

The smoothhound has been in my tank almost a week now and he is less erractic and eating normally. I watched all the smoothound and leopard aquarium videos I could find. It seems that when they sense a wall instead of turning around like a reef tip shark would do or running straight into it they sometime just got vertical snooping at the edges and water line.

Here is a video of the sharks and eel in my tank this morning. I keep the temp between 68-70.xx. I have a 1/2 HP chiller and a fan blowing on the sump. I'm scared to go any cooler because of the tropical tank mates. They are actually more active at a stable 70 then they were when it was 76-80 with no chiller and no fan.

[video=youtube;13aIgVc-Mo4]https://www.youtube.com/watch?v=13aIgVc-Mo4[/video]