Annelida
The annelids include earthworms, polychaete worms, and leeches. All members of the group are to some extent segmented, in other words, made up of segments that are formed by subdivisions that partially transect the body cavity. The internal organs of annelids are well developed. They include a closed, segmentally-arranged circulatory system. Members of the Phylum Annelida can be found throughout the world, in marine, freshwater, and terrestrial environments. Ecologically, they range from passive filter feeders to voracious and active predators
Earthworms- They are the main contributors to enriching and improving soil for plants, animals and even humans. Earthworms are also called night crawlers because they burrow down in the ground during the day and come above ground at night to feed. The earthworm has a closed circulatory system. An earthworm
circulates blood exclusively through vessels. There are three main vessels that supply the blood to organs within the earthworm.
Giant Tube Worms- They are located at the bottom of the Pacific ocean. Because the tube worm has a closed cardiovascular system, blood never leaves the network of blood vessels that continues to supply blood with oxygen from the lungs. The primary oxygen carrying protein that Giant Tube Worms use is hemoglobin.
Leeches- Leeches are known for being "blood suckers" and marine organisms. Unlike other
annelids, the leech has done away with bristles. Leeches can circulate gases and foods through coelomic fluids. Leeches have an open circulatory system. In an open circulatory system ,the blood flows at a very low velocity and at low pressure due to absence of smooth muscles.
Earthworms- They are the main contributors to enriching and improving soil for plants, animals and even humans. Earthworms are also called night crawlers because they burrow down in the ground during the day and come above ground at night to feed. The earthworm has a closed circulatory system. An earthworm
circulates blood exclusively through vessels. There are three main vessels that supply the blood to organs within the earthworm.
Giant Tube Worms- They are located at the bottom of the Pacific ocean. Because the tube worm has a closed cardiovascular system, blood never leaves the network of blood vessels that continues to supply blood with oxygen from the lungs. The primary oxygen carrying protein that Giant Tube Worms use is hemoglobin.
Leeches- Leeches are known for being "blood suckers" and marine organisms. Unlike other
annelids, the leech has done away with bristles. Leeches can circulate gases and foods through coelomic fluids. Leeches have an open circulatory system. In an open circulatory system ,the blood flows at a very low velocity and at low pressure due to absence of smooth muscles.