Why do elasmobranchs attack humans?

Sharks do not actively hunt humans.  There are a number of theories as to why shark attacks occur.  Many happen because humans have done something to injure or corner the shark, which retaliates to defend itself.  Another theory is that sharks sometimes mistake us for a seal or other potential prey and yet another is that we actually unknowingly send communication to a shark via body language that is similar to that which sharks use amongst themselves.  When it comes to rays, it is common for people wading into the water to step on rays that are partially buried under the sand and mud.  Wounds from these stinging spines are generally not lethal, but medical attention should be sought as soon as possible after a sting to be sure to avoid infection.  To avoid being stung by a ray, it is important to shuffle your feet in the sand as you wade into the water to warn resting rays that you are nearby so that they can swim away before you step on them.