Flatworm Research Paper
I. Platyhelmithes Kayla Smith A. Structure and Function of Flatworms Period 2 1. Flatworms are the simplest animals with bilateral symmetry. 2. The tissues in bilaterally symmetrical animals develop from three germ layers: Ectoderm, Mesoderm, and Endoderm. 3. In flatworms, the layers are pressed against one another to form a solid body. 4. Because flatworms do not have a hollow body cavity between the endoderm and mesoderm, they are acoelomates. 5. The acoelomate body plan gives flatworms the thin, dorsoventrally flattened bodies for which they are named. 6. This body shape ensures that no cell in a flatworm is far from the animal’s external
…show more content…
However, the most familiar turbellarian is the freshwater planarian Dugesia. 3. Planarians have a spade-shaped anterior end and a tapered posterior end. 4. They move through the water by swimming with a wave-like motion of their body. 5. Over solid surfaces, planarians glide on a layer of mucus that they secrete, propelled by the Cilia that cover their bodies. Digestions and Excretion in Planarians Planarians feed by scavenging for bits of decaying plant or animal matter.
They also prey on smaller organisms, such as protozoa.
Food is ingested through a muscular tube called the pharynx, which the planarian extends from the middle of it’s body.
The pharynx leads to the highly branched gastro vascular cavity.
Cells lining the cavity secrete digestive enzymes and absorb nutrients and small pieces of food.
The nutrients then diffuse to other body cells.
Organisms that live in fresh water must deal with the water that constantly enters their bodies by osmosis.
Planarians eliminate excess water through a network of excretory tubules that run the length of the body.
Each tubule is connected to several flame cells, which are so names because they enclose tufts of beating cilia that resemble flickering candle …show more content…
Two clusters of nerve cells at the anterior end, the cerebral ganglia, serve as a simple brain.
The receive information from sensory cells and transmit signals to the muscles along a ladder like arrangement of nerves.
A planarians nervous system gives it the ability to learn.
For example, a planarian normally moves away from light, but it can be trained to remain still when illuminated.
Planarians sense the intensity and direction of light with two cup-shaped eyespots located near the cerebral ganglia.
Other sensory cells respond to touch, water currents, and chemicals in the environment.
These cells are distributed over the body, but are most concentrated at the anterior end. Reproduction in Planarians Because planarians are free-living and motile, they can encounter and mate with other individuals of the same species.
Planarians are hermaphrodites- they have both male sex organs (testes) and female sex organs (ovaries).
When two planarians reproduce sexually, they simultaneously fertilize each other.
Their eggs are laid in protective capsules that stick to rocks or debris and hatch in two or three
However, the most familiar turbellarian is the freshwater planarian Dugesia. 3. Planarians have a spade-shaped anterior end and a tapered posterior end. 4. They move through the water by swimming with a wave-like motion of their body. 5. Over solid surfaces, planarians glide on a layer of mucus that they secrete, propelled by the Cilia that cover their bodies. Digestions and Excretion in Planarians Planarians feed by scavenging for bits of decaying plant or animal matter.
They also prey on smaller organisms, such as protozoa.
Food is ingested through a muscular tube called the pharynx, which the planarian extends from the middle of it’s body.
The pharynx leads to the highly branched gastro vascular cavity.
Cells lining the cavity secrete digestive enzymes and absorb nutrients and small pieces of food.
The nutrients then diffuse to other body cells.
Organisms that live in fresh water must deal with the water that constantly enters their bodies by osmosis.
Planarians eliminate excess water through a network of excretory tubules that run the length of the body.
Each tubule is connected to several flame cells, which are so names because they enclose tufts of beating cilia that resemble flickering candle …show more content…
Two clusters of nerve cells at the anterior end, the cerebral ganglia, serve as a simple brain.
The receive information from sensory cells and transmit signals to the muscles along a ladder like arrangement of nerves.
A planarians nervous system gives it the ability to learn.
For example, a planarian normally moves away from light, but it can be trained to remain still when illuminated.
Planarians sense the intensity and direction of light with two cup-shaped eyespots located near the cerebral ganglia.
Other sensory cells respond to touch, water currents, and chemicals in the environment.
These cells are distributed over the body, but are most concentrated at the anterior end. Reproduction in Planarians Because planarians are free-living and motile, they can encounter and mate with other individuals of the same species.
Planarians are hermaphrodites- they have both male sex organs (testes) and female sex organs (ovaries).
When two planarians reproduce sexually, they simultaneously fertilize each other.
Their eggs are laid in protective capsules that stick to rocks or debris and hatch in two or three