BRAZILIAN CRAB SPIDER (Epicadus heterogaster)
Crab spiders or Thomisidae family of the Araneae order. They are called crab spiders because they resemble crabs, with two front pairs of legs angled outward and bodies that are flattened and often angular. Also, like crabs, Thomisidae can move sideways or backward.
Crab spiders do not build webs to trap prey, but are hunters and ambushers. Some species sit on or among flowers, bark, fruit or leaves where they grab visiting insects. Individuals of some species, such as Misumena vatia, are able to change color to match the flower on which they are sitting. Other species, with their flattened bodies, hunt in the crevices of tree trunks or under loose bark. In each case, crab spiders use their powerful front legs to grab and hold onto prey while paralyzing it with a venomous bite.
They are harmless to humans.
Fact Source: http://en.wikipedia.org/wiki/Crab_spider
Other photos you may like:
Brazilian Wandering Spider (one to avoid)
Crab Spider that looks like an Ant
Not to be confused with the Moulting Giant Spider Crab