Form 4: 6.1 Hydrostatic Skeleton

The earthworm moves on land with the aid of _______

Tick TWO types of muscles on the walls of the earthworm's body

• Vertical muscle

• Circular muscle

• Longitudinal muscle

• Horizontal muscle

The diagram shows the movement of an earthworm. What happens to the body of the earthworm when the longitudinal muscles contract and circular muscles relax?

• The segments of the body will shorten and thicken

• The segment of the body will become longer and thinner

What happens to the longitudinal muscles when circular muscles relax

• Contract

• Relax

The antagonistic (opposing) action of the circular muscles and longitudinal muscles exerts a ___________ pressure on the fluid in the earthworm body. Fill in the blank.

The diagram shows a close up image of chaetaes of an earthworm. What happens to the chaetaes if the segments of the body become thicker and shorten?

• Grip on the land

• Lose grip from the land