The Earthworm.

Phylum: Annelids

INTEGUMENTARY

The earthworm's integumentary system is similar to Human's respiratory system. It uses diffusion/osmosis to rid of carbon dioxide, and take in oxygen.

Texture : The earthworm's texture is always moist with mucus. this mucus assists with diffusion, as well as movement. Deep into the skin, there are "bristles" called Setae, giving the worm a "sticky" texture. Setae also anchor the worm's body to assist in movement.

MUSCULAR/MOVEMENT

Muscles : The Earthworm had both circular and longitudinal muscles. These muscles contract, and expand. The "expanding" movement, is caused by it's circular muscles on each segment, relaxing. making the worm thin and long. To make the worm contract and become shorter, is the second layer of muscle located from the head to tail, is underneath the circular muscles. This muscle pulls itself together, making the worm short and stiff.

Movement : This organism constantly contracts and expands to move around. On each segment, tiny bristles "Setae" help hold it down to assist in movement. Synchronizing the contractions, average worms can move up to 185 feet per hour.

DIGESTIVE SYSTEM

This organism consumes soil. Bacteria is located in the soil, therefore making it a variety of decomposed organisms/items. The Earthworm will consume soil, and release "Castings". Castings are full of nutrients that plants may use. Making Earthworms a farmer's best friend, and a vital organism to have in a food chain. (For predators like birds may consume these organisms.

Earthworms have a full digestive system. They have a mouth to eat, a pharynx and esophagus to transport the soil toward the crop. The esophagus contains calciferous glands to help break down the food. It is stored into the crop, awaiting the gizzard. The gizzard will also break down nutrients then transport them into the intestines. The intestines release fluids to assist with digestion. (This explains why our Worm was filled with dirt. For I had accidentally made an incision into the intestine while opening the Integumentary system.) Attached to the intestine are blood vessels. This way the nutrients are transported to where they are needed.

RESPIRATORY SYSTEM

The Earthworm does not have specific respiratory organs. Instead, it uses diffusion to take in oxygen, and get rid of carbon dioxide. This is also one of the reasons why this organism has to be constantly moist. (Ever wonder why there are dried earthworms on the pavement?) This is also why they live underground to prevent drying out. Studies have shown that Earthworms usually come out during the evening, because it is much cooler.

CIRCULATORY SYSTEM

Having a closed circulatory system, blood is constantly circulating. This organism has three major vessels. There is the Aortic Arches (Hearts) located in the top mid section near the head. The Dorsal Blood Vessels located on the dorsal/top side. The Ventral Blood Vessels are located on the underside/ventral side of the worm. The Ventral vessels are to transport blood to the back of the Earthworm's body, whereas Dorsal vessels are to transport blood to the front of the body. These vessels supply blood to organs.

biology.unm.edu

Advantages: Being a decomposer, this organism is much needed for an environment. Built for underground living, it's mucus covering allows for easier movement, and it feeds on dirt! Therefore, i don't think it struggles to find food. This mucus covered, skeleton-lacking annelid can squeeze into many places where organisms that have a skeleton, cannot fit.

Disadvantages:  Lacking a skeletal system, this organism may find trouble when it comes to lifting heavy objects. It is also a disadvantage because it may be easier to kill, since there is no skeleton to support. It must always stay moist, because if it dries out, the earthworm cannot use diffusion to breathe.