Topic 7 Muscular System: Invertebrate Locomotion

Question 1

• Flatworms: contain longitudinal and circular bi-layered muscles that contract against the hydrostatic skeleton. Contraction causes the hydrostatic skeleton to flow longitudinally, lengthening the animal

Answer 1

1. Hydrostatic skeletons

Question 2

• Advance by action of muscles on hydrostatic skeletons
• Bristles in the lower part of each segment, known as setae, anchor worms in the earth while muscles push ahead
• Worms also use peristalsis of longitudinal and circular muscles to worm

Answer 2

2. Annelids (segmented worms)