This kingdom captures a staggering variety of life—from the smallest coral polyp to the largest elephant. Although animal body shapes and life histories vary, there are a few defining characteristics. Animals are heterotrophs, meaning they gain energy from eating other organisms, and have developed from single-celled ancestors to highly diversified and coordinated multicellular forms.
Unlike plant and fungi cells that have rigid cell walls, animal cells are bound by more flexible combinations of proteins. Most animals have cells organized into tissues and are able to move within their environment.
They are soft, slimy tube-shaped organisms without a skeleton or limbs. Earthworms are decomposers that add air and disperse nutrients in the soil as they burrow. As decomposers, they consume dead organic material such as leaves and roots.
After consuming the material, they break it down and excrete it as nutrients. The soft, flexible body of the earthworm is divided into segments, which allows it to easily move through the soil to find food. A common earthworm L. The internal walls separate the segments and are lined with circular and longitudinal muscles. Circular muscles are wrapped around the circumference of each segment Longitudinal muscles extend down the length of each segment.
The muscles create a soft barrier between segments, allowing the segments to be controlled independently. As the earthworm burrows, it squeezes into tightly packed soil. This creates a high-pressure environment that could damage the worm. However, the fluid inside the segments helps prevent damage to the earthworm.
Fluid cannot change volume because the molecules in the fluid are very close together. To move forward, circular muscles in the front of the body contract.
Contracting those muscles makes the segments thinner and longer, allowing the worm to reach forward. The earthworm also relies on anchors, called setae, which are short stiff hairs that can hold onto the soil. Reproduction Mature earthworms have a clitellum or a saddle. The size, shape, colour and position of the clitellum varies between species.
The clitellum means the earthworm is an adult and is ready to mate and lay eggs. Earthworms reproduce by forming a small egg sac — called a cocoon — at the clitellum. Adaptation is an evolutionary process whereby an organism becomes increasingly well suited to living in a particular habitat.
Natural selection results in helpful traits becoming more common in a In this activity, students use observation to explore earthworm anatomy and the nature of science.
By the end of this activity, students should be able to: identify various physical When you look at the world around you, how do you categorise or group what you see? One of the broadest groupings is 'living' and 'non-living'. This may sound simple, but it is sometimes Add to collection. Then do the journaling project at the end.
Seeing : Earthworms have no eyes, but they do have light receptors and can tell when they are in the dark, or in the light. Why is being able to detect light so important to a worm? Hearing : Earthworms have no ears, but their bodies can sense the vibrations of animals moving nearby. Thinking and feeling : Worms have a brain that connects with nerves from their skin and muscles. Their nerves can detect light, vibrations, and even some tastes, and the muscles of their bodies make movements in response.
Breathing : Worms breathe air in and carbon dioxide out, just like us, but they don't have lungs. They can't breathe through their mouth, and certainly can't breathe through their nose because they don't even have one! They breathe through their skin. Air dissolves on the mucus of their skin, so they MUST stay moist to breathe. If worms dry out, they suffocate. As fresh air is taken in through the skin, oxygen is drawn into the worm's circulatory system, and the worm's hearts pump the oxygenated blood to the head area.
The movements of the worm's body make the blood flow back to the back end of the body, and the hearts pump the blood forward again. Carbon dioxide dissolves out of the blood back to the skin. This fluid helps maintain the worm's shape , even when under the pressure of the soil underground.
For an earthworm to actually press itself through the soil, they must combine several of these elements at one time. Earthworm motion involves utilizing each segment's muscles individually. The worm expands part of its body, using a combination of hydrostatic pressure and its setae to hold that section in place against the soil.
Then, it tightens and lengthens the muscles of the next section to force itself forward through the soil. It can also use the opposite to push itself backward if necessary.
To further help the earthworm move through the soil safely, they have a hardened, slightly pointed area on their head. This helps the worm force its head through the earth and open even the smallest cracks in the soil. The tunnels that earthworms create don't just serve them either! This helps plant roots absorb additional nutrients. In addition to soil aeration, earthworms also leave behind droppings in the soil that they dig through.
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