As you have experienced, we can swim with a pack of hungry sharks and do it safely. According to Erich Ritter, a bull shark needs to eat 4 per cent of its own bodyweight in fish each day. That means that some of these animals are eating 20 to 30lb. I had seen the bull sharks working in pairs, even if that meant that only one of them got any of the fish scraps Gary threw in. I thought it more likely that they simply found it convenient to hunt in packs, but I wanted to learn more about this communication theory.
Birds are more closely related to mammals than sharks are to most fishes.
If they were related, it was more than 500 million years ago. A shark's brain related to its bodyweight out-ranks that of many mammals. We are out here in the water every day, and yet we know so little. It can also pick up differing frequencies of vibration. We think the lateral-line system is used for communication between sharks.