The member of this phylum are terrestrial or aquatic having an organ system level organisation bilaterally symmetrical, triploblastic , segmented and eucoelomate animals ?

Options

A. Mollusca
B. Arthropoda
C. Platyhelminthes
D. Echinodermata

Answer

To solve the question regarding the phylum that includes terrestrial or aquatic animals with specific characteristics, we will analyze each option provided based on the given traits:

1. **Understanding the Characteristics**:
- **Terrestrial or Aquatic**: The organisms can live on land or in water.
- **Organ System Level of Organization**: This means that their body is organized into cells, tissues, organs, and organ systems.
- **Bilaterally Symmetrical**: If you draw a line down the middle of the organism, both halves will be mirror images.
- **Triploblastic**: The organisms have three germ layers: ectoderm, mesoderm, and endoderm.
- **Segmented**: The body is divided into segments.
- **Eucoelomate**: They possess a true coelom, which is a body cavity lined by mesoderm.

2. **Analyzing the Options**:
- **A. Mollusca**: Mollusks are primarily soft-bodied and may not exhibit segmentation. They are not typically classified as segmented or eucoelomate in the same way as other phyla.
- **B. Arthropoda**: Members of this phylum are indeed segmented, bilaterally symmetrical, triploblastic, eucoelomate, and can be found in both terrestrial and aquatic environments. They also have an organ system level of organization.
- **C. Platyhelminthes**: Flatworms are not segmented and are typically acoelomate (lacking a true coelom).
- **D. Echinodermata**: While echinoderms are coelomate, they are not bilaterally symmetrical as adults; they exhibit radial symmetry.

3. **Conclusion**:
Based on the analysis of the characteristics and the options provided, the correct answer is **B. Arthropoda**. This phylum includes organisms like insects, arachnids, and crustaceans, which fit all the criteria mentioned in the question.