Concerning Sharks: Cleaning time, don't get vacuumed up

Shark Webcam, courtesy of Shark Lagoon
It's cleaning time! Imagine my surprise when I went to check up on the sharkies, only to be greeted with this.

Well... I obviously can't know for sure that they are actually cleaning the tank, but this is the only logical conclusion I can reach. I'm assuming it's like an underwater vacuum.... What's interesting is, the sharks are still in the tank, although, I guess it would present a challenge to move them all... Anyway, not all to much observe here, just interesting how these animals don't really seem to be bothered by the machinery, nor the two divers. As I said, they are more afraid of you, than you of it.

 No divers yet.

There they are! Notice the shark's head peeping out to the right of the diver.

 Two black tips can be seen further back in the tank. The animals, do seem to be keeping their distance, from the weird tube thing.

Where are you all hiding?
There's one shark slightly to the right. I think it might be a bull shark. I've suspected that the aquarium might have a couple bull sharks. But I'm not certain, I'll be sure to look into it soon.