Identical twins occur when one egg is released and is fertilized by one sperm, and the pre-embryo later splits into two two eggs are released and are fertilized by the same sperm two eggs are released and are fertilized by two different sperm one egg is released and is fertilized by one sperm, and the fetus later splits into two

Answerone egg is released and is fertilized by one sperm,and the embryo later splits into two

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.