Dangerous animals and insects
Marine life: Sea urchins and jellyfish shouldbe avoided. And never sit, stand or touch any of the coral (unless it's sand, do not stand). It kills it and it takes decades to grow. Plus there is "fire coral" that you may not be familiar with and it has a certain sting.
Insects: Just wear repelleant, as they (mosquitos and sand flies) can be brutal to visitors (dunno why they leave locals alone and bite the tourists, but they do! When I first moved here I got eaten alive...a couple weeks later...nothing! Go figure).
Mammals: Nothing to avoid. If an iguana or mongoose doesn't want to be bothered, it will run away. You won't get near it. However, some iguanas are so tame that they beg for food. Throw the food to them instead of trying to have them eat it out of your hand. They have very bad aim and might get your finger. Doesn't hurt much, but it can bleed.
Look over our section on fauna:
in the 10 years I lived on St. Thomas I only saw one centipede, down at the stadium. It was about 2 feet long and had pincers the size of your thumb and index finger. One of the Frenchies selling fish ran over and chopped its head off with a machete. BTW, centipedes bite is deadly.