Source: The San Tan Valley, AZ weather data displayed above is derived from the NOAA (National Oceanic and Atmospheric). Air quality and pollution data is derived from the EPA (United States Environmental Protection Agency).
A hydra is a small multicellular organism in the genus of the same name. These tiny animals are found in fresh water all over the world, and they have a number of distinctive traits that make them interesting to scientists.
Hydra &mdash; Classifications. Scientists aim to describe a single 'tree of life' that reflects the evolutionary relationships of living things. However, evolutionary relationships are a matter of ongoing discovery, and there are different opinions about how living things should be grouped and named. EOL reflects these differences by supporting several different scientific 'classifications'. Some species have been named more than once.