Annelida

Question 1

Advantages of coleom

Answer 1

gut with muscle: (overall increase in feeding and digestive efficiency)
grinding ability (feeding on complex foods)
peristalsis (food can be moved independently of body)
compartments for specific digestive functions (grinding, storage, moisture extraction)
Gut environment can be controlled: nerves, hormones
Allows feeding on plant material (colonisation of land)
Space for additional digestive organs which make digestion for efficient

Question 1

What are the greatest ‘achievements’ of the annelids?

Answer 1

-coelomate condiditon: efficient feeding, including herbivory

-efficient locomotion: crawling, burrowing

-terrestrial existence (earthworms)

-ectoparasitism (leeches)

Question 2

What are/were the major selective pressures in the evolution of the annelids?

Answer 2

predators (selective advantages of locomotion, burrowing, living on land)

competitors (living on land: vacant space)

plants available for food: coelomate condition & thus efficient digestion (especially for herbivory)