<P> The earthworm has a dual circulatory system in which both the coelomic fluid and a closed circulatory system carry the food , waste , and respiratory gases . The closed circulatory system has five main blood vessels : the dorsal ( top ) vessel , which runs above the digestive tract ; the ventral ( bottom ) vessel , which runs below the digestive tract ; the subneural vessel , which runs below the ventral nerve cord ; and two lateroneural vessels on either side of the nerve cord . The dorsal vessel moves the blood forward , while the other four longitudinal vessels carry the blood rearward . In segments seven through eleven , a pair of aortic arches rings the coelom and acts as hearts , pumping the blood to the ventral vessel that acts as the aorta . The blood consists of ameboid cells and hemoglobin dissolved in the plasma . The second circulatory system derives from the cells of the digestive system that line the coelom . As the digestive cells become full , they release non-living cells of fat into the fluid - filled coelom , where they float freely but can pass through the walls separating each segment , moving food to other parts and assist in wound healing . </P>
<P> The earthworm has a dual circulatory system in which both the coelomic fluid and a closed circulatory system carry the food , waste , and respiratory gases . The closed circulatory system has five main blood vessels : the dorsal ( top ) vessel , which runs above the digestive tract ; the ventral ( bottom ) vessel , which runs below the digestive tract ; the subneural vessel , which runs below the ventral nerve cord ; and two lateroneural vessels on either side of the nerve cord . The dorsal vessel moves the blood forward , while the other four longitudinal vessels carry the blood rearward . In segments seven through eleven , a pair of aortic arches rings the coelom and acts as hearts , pumping the blood to the ventral vessel that acts as the aorta . The blood consists of ameboid cells and hemoglobin dissolved in the plasma . The second circulatory system derives from the cells of the digestive system that line the coelom . As the digestive cells become full , they release non-living cells of fat into the fluid - filled coelom , where they float freely but can pass through the walls separating each segment , moving food to other parts and assist in wound healing . </P>
what are the hearts of a worm called
what are the hearts of a worm called
a pair of aortic arches rings the coelom
a pair of aortic arches rings the coelom