Shark facts and attacks

(WTNH) -- Critics are questioning a Ridgefield family's decision to take their 5-year-old daughter to swim with sharks, but how dangerous are sharks?

In 2011, there were 75 shark attacks worldwide, 29 of which occurred in the U.S. Officials say there was a downward trend of shark attacks in the U.S. while the number doubled between 2010 and 2011 worldwide. (Source: Livescience.com )

According to a study conducted by the Florida Museum of Natural History, there is a 1 in 3,748,067 chance of dying from a shark attack, as compared to dying from heart disease, which is a 1 in 5 chance, or in a car crash 1 in 84.

Nurse sharks are generally, are harmless to humans, but will bite defensively if bothered by divers. (Source: National Geographic )

Lemon sharks are a small threat to humans, they rarely attack when unprovoked. There have been no fatal attacks by this species. (Source: Florida Museum of Natural History )

Caribbean Reef sharks are not considered a threat to humans. However, like most sharks, they can become aggressive if they feel threatened. (Source: marinebio.org )

Sharks species that pose the biggest threat to humans:
1. "Great" white shark
2. Tiger shark
3. Bull shark
4. Sand tiger shark
5. Requiem shark

*Source: Florida Museum of Natural History