Question

What is morphology of earthworm?

Answer 1

Morphology of earthworms.Earthworms have long cylindrical body.the body is divided into more than hundred short segments which are similar.The dorsal surface of the body is marked by a dark median mid dorsal line along the longitudinal axis of the body.

Answer 2

Answer:

The external features (morphology) of earthworm :

• Earthworms have long, narrow, cylindrical body.
• Their body is divided into short and similar segments.
• These similar segments are known as metameres. They are about 100 to 120 in number.

• These metameres divide body both externally and internally, such type of segmentation is called metameric segmentation or metamerism.
• These segments are separated from each other by distinct ring-like grooves or annuli.

• The dorsal surface of their body is recognised by a dark median/mid-dorsal line, which is in fact a dorsal blood vessel beneath the skin.
• Their ventral surface can be recognised by the presence of genital apertures (pores).

• The earthworms do not possess a distinct head nor any specialised sense organs-like eyes or ears.
• So, the anterior end of these worms consist of mouth and the prostomium.

• Mouth is a crescentric aperture at the anterior end of first segment. This segment is known as peristomium (or buccal segment).

• The dorsal edge of peristomium projects forward above the mouth, as a small fleshy lobe called prostomium which serves as covering for the mouth. It is used as a muscular probe in burrowing. It is also sensory in function.

• Other external features of earthworm include – presence of clitellum, setae and various apertures