Earthworm Dissection Quiz

Explanation
Earthworms belong to the Phylum Annelida. This phylum includes segmented worms, and earthworms are a well-known example of this group. They have a long, cylindrical body with numerous segments, each containing muscles and bristles called setae. Earthworms play a crucial role in soil health and nutrient cycling. They burrow through the soil, improving its structure and allowing air and water to penetrate. They also consume organic matter, breaking it down and releasing nutrients back into the soil. Their presence is an indicator of healthy soil ecosystems.

Explanation
A coelom is a fluid-filled body cavity surrounded by the mesoderm. This cavity is present in many animals, including humans, and serves various functions such as providing a space for organs to develop and move independently, acting as a hydrostatic skeleton, and enabling efficient circulation of nutrients and waste products. The mesoderm, one of the germ layers in embryonic development, gives rise to various structures including muscles, bones, and connective tissues. Therefore, the correct answer is "A fluid-filled body cavity surrounded by the mesoderm."

Explanation
This question is asking about the number of classes in a specific phylum. The correct answer is 3. This means that the phylum in question is divided into three distinct classes.

Explanation
Earthworms belong to the class Oligochaeta, which is a class of segmented worms. These worms have a cylindrical body with numerous segments and bristles called setae. Earthworms are known for their important role in soil fertility as they help to break down organic matter and improve the soil structure. They also play a vital role in the ecosystem as a food source for many animals. Therefore, it is true that earthworms belong to the class Oligochaeta.