What is a Pollinator?
A pollinator is an animal that causes plants to make fruit or seeds. They do this by moving pollen from one part of the flower of a plant to another part. This pollen then fertilizes the plant. Only fertilized plants can make fruit and/or seeds, and without them, the plants cannot reproduce.
In order to pollinate a plant, the pollinator must touch parts of the flower of the plant. Because of this, animals like bees, hummingbirds and some kinds of butterflies are the best pollinators, because they get their food from the flower of the plant and so brush up against parts of the flower. Other insects such as spiders and flies or wasps may use the flower for a hiding place, or may occassionally scavenge from the flower. These animals can also be pollinators, but they aren't as efficient as bees at their tasks.
Some kinds of plants, such as soybeans do not require pollinators at all, and some can be pollinated by wind in the ecodome blowing on the plants. But others, such as raspberries or alfalfa won't reproduce or grow fruit without pollination, and many fruit and vegetable plants, such as strawberries reproduce more slowly and produce less fruit without pollinators around.