Symmetry of ctenophores is generally

Options

A. Bilateral
B. Radial
C. Biradial
D. Absent

Answer

**Step-by-Step Solution:**

1. **Understanding Symmetry in Animals**: Symmetry in animals can be classified into three main types: asymmetrical, radially symmetrical, and bilaterally symmetrical.

2. **Defining Asymmetrical Animals**: Asymmetrical animals cannot be divided into two equal halves by any plane. An example of this type is found in some sponges (Porifera).

3. **Defining Radial Symmetry**: Radially symmetrical animals can be divided into two equal halves by multiple planes passing through the center. An example of this is a spherical object, which can be cut in many ways through its center.

4. **Defining Bilateral Symmetry**: Bilaterally symmetrical animals can be divided into two equal halves by a single plane. This type of symmetry is common in organisms like humans and most animals.

5. **Introducing Ctenophores**: Ctenophores, also known as sea walnuts or sea jellies, exhibit characteristics of both radial and bilateral symmetry.

6. **Analyzing Ctenophore Structure**: Ctenophores have a generally spherical shape, which suggests radial symmetry. However, they also possess two ciliated tentacles that affect their symmetry.

7. **Determining the Type of Symmetry in Ctenophores**: While they can be considered radially symmetrical due to their overall shape, the presence of the two tentacles means they can also be divided into two equal halves by a single plane.

8. **Conclusion on Ctenophore Symmetry**: Therefore, ctenophores exhibit a type of symmetry known as biradial symmetry, which incorporates elements of both radial and bilateral symmetry.

9. **Final Answer**: The symmetry of ctenophores is generally biradial.

---