Worms do many of the things humans do to survive. They breathe, move around, reproduce, and eat. Worms have the epidermis; which is like our skin, a layer of nerve tissue, which acts like our sense of touch. Instead of having just one heart, they have five hearts.
These hearts regulate blood flow and produce a pulse, just like ours. They have a dorsal and a ventral vessel branching off the hearts, which transports the blood, rich with oxygen and nutrients through the body. The digestive system is similar; we both have a mouth, stomach, and intestines.
What are the differences between your organ systems with those of the earthworm?
- Transports blood and oxygen through the body
- Heart main component of the system
- The heart is the muscle used to pump blood.
- Closed system
- Circulates blood through vessels
- Vessels are aortic arches, dorsal blood vessels, ventral aortic vessels, functions
- Like the human heart, there are 5 of them, pumps blood into dorsal and ventral blood vessels.
- The dorsal vessel carries blood to the front of the worm’s body.
- The ventral vessel carries blood to the back of the worm’s body.
- No bones of skeleton; invertebrate.
- Entire internal skeletal of the body
- Consist of all bones, tissue, cartilage, ligaments, and tendons in the body.
- The brain is connected to the ventral nerve cord, which runs the length of the body
- Segment ganglion branches off each central nerve
- Segment ganglion must be well coordinated with each other.
- Consists of two parts; central and peripheral nervous system.
Problem Statement: What is the anatomy of an earthworm?
Worms are invertebrates; they do not have a backbone. They have long bodies that are divided into similar segments. They have a tongue-like lobe above the mouth called the prostomium.
The prostomium is a sensory device. They don’t have eyes nose, or ears.
They depend on their prostomium and sensory receptors in their skin to feel their way through soil. The first body segment is called the peristomium; it contains the mouth.
Adult worms have a distinct swelling called the clitellum, its located about one third of the way down the earthworm.
The clitellum is only found in adult worms, younger worms don’t have one. The tubercular pubertatis are glandular swelling located on both sides of the clitellum. The genital tumescence is areas of modified skin. These are openings through which follicles of genital setae open. The shorter part to one side of the clitellum is the anterior, or head of the worm. This end is more pointed than the posterior end. The periproct is the last part of the earthworm.
- Dissecting pins
- Paper towel
- Dissection tray
- Preserved earthworm
By cutting the earthworm we will know how its internal organs work and how they are compared to human’s internal organs.
Lay the worm on your hands. Start your dissection about an inch posterior to the clitellum. Insert the scissors by the side and cut in a straight line all the way up through the mouth. Using the forceps and dissection pins, carefully pull apart the two flaps of skin and pin them flat on the tray.
Like a human, a worm consumes food through one end and excretes waste through the other, extracting the nutrients it needs as the food passes through the alimentary canal. A worm’s alimentary canal, like a human’s, has several parts.
Specialized sensory cells in the mouth, called the buccal cavity, detect chemicals the worm needs such as sucrose and saline.
Earthworms have five hearts with valves and chambers. These organs perform the same basic function of keeping the worm’s blood flowing as it distributes oxygen and nutrients throughout the body.
Humans have arteries to carry freshly enriched blood away from the heart, and veins that return the depleted blood to be refreshed; earthworms have ventral and dorsal vessels that perform the same basic functions. As a human, an earthworm’s blood is red.
Explain why the crop and gizzard are important parts of the digestive system of the earthworm. – As an earthworm worms its way through dirt, soil enters its body through the mouth. This dirt is pulled to the gizzard by the crop. Since worms don’t have teeth and can’t chew their food, the muscular gizzard helps break it down into smaller pieces (birds do this too).
Without the crop, the food couldn’t get to the gizzard. And without the gizzard, the worm could not digest its food or push food into the intestines, since it would be too rough or hard. In this way, all the organs in the worm’s digestive system work together to help it eat and survive.
In conclusion, we can say that the earthworm dissection let us know the differences and similarities between humans and worm and help us to understand natural comportment of the internal organs of this kind of animal.