Residential central air conditioning is rated by a Seasonal Energy Efficiency Ratio or SEER system. Since 2006, units sold in the US must have a SEER of at least 13. Air conditioning systems marked with an Energy Star meet strict US government energy-efficiency guidelines. Additional costs:
Earthworm. An earthworm is one of the animals that are classified in the Annelida phylum. Like many other animals, the earthworm has a closed circulatory system. A closed circulatory system means that the blood is confined to blood vessels and its blood recirculates so it gets maximum use. The worm uses its bodies suface area to absorb oxygen from the soil instead for using lungs or gills.
1 They have a circulatory system and a digestive system. 2  Flatworms, roundworms, and segmented worms are all invertebrates. 3  Some species of each type of worm are free-living, meaning they are not dependent on another organism for food. 4  Segmented worms are the most complex animals of these three invertebrates. Students will then continue with their Internet research to compare flatworms, roundworms, and segmented worms by completing the Worm Comparison worksheet. 2  They should use their research to find more information in order to describe how these three types of worms are similar and how they are different.