Plankton (singular plankter) are a diverse group of organisms that live in the water column of large bodies of water and that cannot swim against a current. They provide a crucial source of food to many large aquatic organisms, such as fish and whales.lankton are primarily divided into broad functional (or trophic level) groups: 1  Phytoplankton (from Greek phyton, or plant), autotrophic, prokaryotic or eukaryotic algae that live near the water surface where there is sufficient light to support photosynthesis.
Tree swallows breed between May and September. They raise one brood per year. Tree swallows usually nest solitarily. However, they may nest near other tree swallows if nest cavities are close together. Tree swallows build their nests in late April or early May. Their nests are usually built in holes in dead or live trees or in hollow stumps. The female builds the nest using grasses, mosses, rootlets, and aquatic plants.
When aquatic insects hatch, Barn Swallows may join other swallow species in mixed foraging flocks. You can find the adaptable Barn Swallow feeding in open habitats from fields, parks, and roadway edges to marshes, meadows, ponds, and coastal waters. Their nests are often easy to spot under the eaves or inside of sheds, barns, bridges and other structures.