ANNELIDA OVERVIEW
The Annelids consist of earthworms, polychaete worms, and leeches. They are made up of segments that are formed by parts that transect the body cavity. The body wall of annelids is made up of circular and longitudinal muscle fibers. Chitonous hair-like structures, called setae that project from their cuticle. The internal organs of annelids include a close, segmentally-arranged circulatory system. The internal organs are also well developed. The digestive system includes the mouth and anus, which is a complete tube. The nervous system includes cephalic ganglia that run the length of the animal. Annelids have well developed eyes. Annelids can either be monoecious or dioecious. Some sexually reproduce while others may or may not have larva present. Anneldia can be found in many places, including freshwater, marine, and terrestrial places. THey can be filter feeders to active predators.
LEECHES
Leeches are worms that have suckers on each end. They can range in size from half an inch to ten inches long. Usually brown or black in color, they feed on decaying plant material. They also can feed on the blood/tissue of other animals. Leeches can suck blood in two ways. They use a proboscis to puncture your skin. They can also use their jaws and many teeth. Their homes usually involve water, and they find you by detecting skin oils, blood, and heat. Leeches are helpful in taking blood away from the organism. They are hermaprhodites, which means they have both female and male reproductive organs. They reproduce by reciprocal fertilization. Their bodies are flattened and are sometimes filled with spots/stripes. Leeches hide while resting, and they are nocturnal as well. This helps them to avoid predators and locate resting prey. Leeches breathe through their body wall, whereby aquatic leeches move to the surface when in water with a low oxygen levels. The body surface also contains a number of sensory organs, and together with those on the head they can detect changes in light intensity, temperature, and vibration. Leeches are also equipped with chemical receptors on their head to provide them with a sense of smell. Plus, they have eyes, sometimes only one pair but often several pairs.
citation : http://www.flyingdusun.com/004_Features/036_leeches.htm
citation : http://www.flyingdusun.com/004_Features/036_leeches.htm
EarthWORMS
Earthworms breathe in the same way as their aquatic ancestors. They don't have lungs, but instead breathe through the skin. In order for gas exchange to take place this way, the outermost layers of an earthworm are thin and must be kept moist. Mucous is excreted onto the skin to keep it moist. It is also wet by body fluid which is excreted through 'dorsal pores' located along the dorsal (back) midline in the grooves between the segments. This need for moisture restricts their activities to a burrowing life in damp soil. They emerge only at night when the evaporating potential of the air is low, and retreat deep underground during hot, dry weather. Light-sensitive tissues near the worm's head enable it to detect light, so they can avoid venturing out by day.
citation : http://www.wormdigest.org/content/view/209/17/
citation : http://www.wormdigest.org/content/view/209/17/
rag-worms
Ragworms are part of the family of polychaete worms. They breathe through their skin like earthworms, because they do not have lungs. They can be an active predator that pursues an assortment of small ocean creatures and sifting through mud for food.