For fertilization to occur in angiosperms, pollen has to be transferred to the stigma of a flower: a process known as pollination. Gymnosperm pollination involves the transfer of pollen from a male cone to a female cone. After fertilization, the zygote divides to form the embryo and the fertilized ovule forms the seed. Pollination occurs when pollen grains from the anther land on a stigma. Fertilization occurs when one of the sperm cells fuses with the egg inside of an ovule. After fertilization occurs, each ovule develops into a seed. Pollination refers to the transfer of pollen from an anther to stigma. Fertilization can only occur AFTER pollination and refers to the joining of sperm and egg inside the ovary. Without pollinators, the human race and all of Earth's terrestrial ecosystems would not survive. Animals that assist plants in their reproduction as pollinators include species of bats, butterflies, moths, flies, birds, beetles, ants, and bees.