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The Monarch Butterfly is known for its orange and black pattern. The North American Monarch is most popular for its annual migration from the United States to Canada. Their cardiovascular system is an open system in which hemolymph is the body fluid. The dorsal vessel, which is closed, runs from the end of the body all the way to the head. The heart is located all the way in the abdomen and the aorta is from the thorax to the head. As the hemolymph travels from the abdomen, or heart, it passes through openings called ostia in which hemolymph is released and pumped through the wings and through the antennae and legs.