How does the frogs vestigial thumb survival?

Frogs have their way of avoiding the predators like camouflage, squirting the poisonous liquid out of their system and through their vestigial thumbs. This organ helps them by avoiding predation by stealth which makes them quiet and silent in moving so that predators won't notice them readily. 

Wetlands form where water and land meet. a lake with a wetland fringe can fill in with decayed plant and animal material to become a wet meadow. a pond can fill in to become a bog or fen. sediment can fill in a river marsh to become a swamp.flooding of coastal lowlands from rising sea levels has created broad coastal marshes that are protected from wave action by barrier islands or reefs. coastal wetlands also form when rivers deposit sediment as they reach the ocean. plants then take root and hold the soil firm against the forces of tides and waves.