this is a perfect example of not listening to the pre-dive briefing, The basic rule is always keep eye contact with the largest approaching shark and if it turns you need to turn with it keeping eye contact. Diving with tigers beach is safe, all you need to do is follow the rules.
This alien-looking creature is Bytiscus marginalis larvae, a predatory feeder on aquatic insects, tadpoles, small fish, and salamanders. Its hunting method involves seizing its prey with its 3-5 mm long jaws, injecting it with a paralyzing digestive fluid, and absorbing the liquefied tissue.
This behavior is called Hazing, Crows will haze hawks and other birds of prey to get them out of their territory or defend their nests, other birds will haze raptors too (like ruby throated hummingbirds), Hawks usualy dont retaliate unless its "worth" spending their energy on it.