Question

Annelid anatomy can be described as "a tube within a tube." Explain.

Short answer

Annelids are referred to as 'a tube within a tube' because they have an outer tube, the body wall, and an inner tube called the digestive tract.

Step-by-step solution

Annelids

Annelids can be found both in the water and on land. They might be parasitic or free-living. Annelids have unique segments or metameres on their bodies. They have longitudinal and circular muscles that let them move around.

Earthworms and blood-sucking leech are some examples of annelids.

Body plan of annelid

The alimentary canal of annelids runs throughout the body's length and is considered the inner tube. Its body wall is like an outer tube. The coelom separates the inner and the outer tubes.

Body plan is like 'a tube within a tube'

The body plan of annelids is considered as 'a tube within a tube.’ This is because it has a superficial blanket of cuticle, epidermis, muscles, and an interior covering of the alimentary canal in the coelomic cavity.