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.
Barn Swallow. Glistening cobalt blue above and tawny below, Barn Swallows dart gracefully over fields, barnyards, and open water in search of flying insect prey. Look for the long, deeply forked tail that streams out behind this agile flyer and sets it apart from all other North American swallows. Barn Swallows often cruise low, flying just a few inches above the ground or water. True to their name, they build their cup-shaped mud nests almost exclusively on human-made structures.