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How is a worms body divided?
Earthworm structure The body is divided into segments, and furrows on the surface of the body mark the division between each segment. All segments, except the first, have eight retractable bristles which help the earthworm to grip surfaces as it moves.
Which plan is present in roundworm?
Roundworms (nematodes) are bilaterally symmetrical, worm-like organisms that are surrounded by a strong, flexible noncellular layer called a cuticle. Their body plan is simple. The cuticle is secreted by and covers a layer of epidermal cells.
How do segmented worms feed?
Most segmented worms like the earthworm, feed on dead organic matter. Leeches (Figure below), however, can live in fresh water and suck blood from their animal host. You may have noticed many earthworms in soil. Earthworms support terrestrial ecosystems both as prey and by aerating and enriching soil.
How do roundworms feed?
Diet/Feeding Nematodes feed on organic matter, both dead and alive such as small animals including other worms, or on diatoms, algae, fungi and bacteria. Some eat plants by piercing the stem or root and sucking out the contents.
Why are earthworms beneficial to humans?
But it’s an intriguing example of how earthworms can help humans. As they move through the soil, earthworms loosen and mix it up, helping to aerate and drain it. This brings nutrients to the surface, making the soil more fertile, and helps prevent flooding and erosion.
Which is the most complex animal with a worm body plan?
Segmented worms (phylum Annelida) are the most complex animals with worm-like body plans. A study of worms can illuminate a possible history of how some organ systems and body features evolved. Worms are invertebrate animals with bilateral symmetry. Worms have a definite anterior (head) end and a posterior (tail) end.
What kind of body plan does a flatworm have?
The flatworm’s bilateral body plan has a head with a brain and stereo eyes that enable it to actively hunt. Its mouth and pharynx are in the center of its underside. With no circulatory system, the gut distributes food to all parts of the body.
What makes up the body of an annelid worm?
Figure 17-1 Annelid body plan. The annelid body typically has an anterior prostomium, a segmented body, and a terminal portion bearing the anus ( pygidium ). The prostomium and pygidium are not considered metameres, but anterior segments often fuse with the prostomium to make up the head.
What kind of body does a roundworm have?
Roundworms are characterized by a simple worm-like structure with a lack of features such as cilia or a well-defined head. They have an internal body cavity, called a pseudocoelom, which looks like a tube within a tube and runs the whole length of their bodies.