Are flatworms bilateral or radial?
The phylum Platyhelminthes, the flatworms, shows bilateral symmetry. In bilateral symmetry, you create two matching halves by drawing a line from the anterior (head) end of the organism to the posterior (tail) end.
What type of symmetry do flatworms have?
Flatworms’ bodies are bilaterally symmetrical and they have a defined head and tail region. They have a central nervous system containing a brain and a nerve cord. Clusters of light-sensitive cells on either side of their head make up what are called eyespots.
Are flatworms bilateral symmetry?
B140: Flatworms. Flatworms and nearly all other animals from here on are bilaterally symmetrical (right and left halves are mirror images). The front end of such animals usually forms a distinct head. However, flatworms still have a single all-purpose cavity with only one opening.
Are Planaria radial or bilateral symmetry?
Planarians have three tissue layers (shown above) and are bilaterally symmetrical. Bilaterally symmetrical objects can be divided into identical right and left halves, like a shovel. Flatworms can move in several ways. For example, using cilia on its ventral surface, the planarian slides about in search of food.
Why do flatworms have bilateral symmetry?
Flatworms have no true body cavity, but they do have bilateral symmetry. Due to the lack of a body cavity, flatworms are known as acoelomates. Flatworms have an incomplete digestive system. This means that the digestive tract has only one opening.
Do flatworms have tentacles?
Some flatworms have tiny tentacles over their heads. Most of the commonly seen flatworms only have pseudotentacles on their heads, a pair of tiny ear-like structures made out of folded edges of their bodies. They are not real tentacles like those of a snail.
Do flatworms have a circulatory system?
Flatworms have no circulatory system. Animals without a circulatory system have limited abilities to deliver oxygen and nutrients to their body cells because of the way that molecules behave.
What are 3 characteristics of flatworms?
Distinguishing features
| Attribute | Cnidarians and Ctenophores | Platyhelminthes (flatworms) |
|---|---|---|
| Bilateral symmetry | No | Yes |
| Number of main cell layers | Two, with jelly-like layer between them | Three |
| Distinct brain | No | Yes |
| Specialized digestive system | No | Yes |
Are flatworms decomposers?
Since most flatworms are parasitic in nature, they are mostly responsible for sickness or disease. However, some free-living flatworms do help the environment by acting as decomposers.
Are flatworms bilaterally symmetrical and have a clearly defined head?
These worms are bilaterally symmetrical, meaning that their two sides reflect each other. They usually have a recognizable head, which houses gravity and light-receptive organs, and eye spots.
Are flatworms segmented?
The body is not segmented; spongy connective tissue (mesenchyme) constitutes the so-called parenchyma and fills the space between organs. Flatworms are generally hermaphroditic—functional reproductive organs of both sexes occurring in one individual.
Do flatworms have a complete digestive system?
Physiological Processes of Flatworms Most flatworms have a gastrovascular cavity rather than a complete digestive system; in such animals, the “mouth” is also used to expel waste materials from the digestive system. Some species also have an anal opening.