Macrobdella Decora
The Macrobdella Decora is more commonly known as the Freshwater Leech, it can be found in many different areas such as lakes, ponds, rivers and other aquatic regions. This organism is more commonly found on land than in water, roughly 20% of this species live in water instead of land. The Macrobella Decora are mostly either black or brown in color and can be used for medicine. In addition, it is also believed that this organsim may have possibly evolved from a flatworm.
The Macrobdella Decora has an open circulatory system that does not have any blood vessels at all whatsoever. In order to survive, this organism gets blood to flow through its body cavities through its heart pumping. However due to a lack of vessels, the blood in this organism circulates at a very slow speed. In addition to this, the direct contact that is involved between the organism's cells and nearby salt water allows an exchange of nutrients to help it survive.