Birds eat mosquitoes that carry the zika virus. Bats pollinate plants such as bananas, peaches, and agave. Iodine supplements are extracted from marine algae. Roots of vegetation trap and hold soil on the banks of rivers. Fungi, bacteria, and deep-sea organisms produce anticancer and anti-biotic chemicals. Fungi distribute nutrients in tropical rainforests through a network of fibers called hyphae. Ocean algae perform photosynthesis. Wetland plants function as natural sponges that trap and slowly release water. Nitrogen-fixing bacteria and nitrifying bacteria are the only source of nitrogen for wild plants and food crops. Decomposition breaks apart dead bodies. A spider eats about 2,000 insects each year. Kelp, a type of marine algae, is used as a thickening agent to produce ice cream, jelly, salad dressing, and toothpaste.