PRESENTED BY:

HINA AMIR

Class Clitellata• Include earthworms and leaches.

Symplesiomorphic Characters:

1. Clitellum for cocoon formation.

2. Few or no setae.

3. Monoecious

Subclass Oligochaeta

• 3,000 species• Aquatic as well as terrestrial.• Include earthworms.

External Structure

• Few Setae.• Prostomium having small lobe.• Clitellum.• Cuticle.

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Locomotion

• Antagonism of circular and longitudinal muscles.

• Burrowing ……..Coelomic hydrostatic pressure.

Feeding and digestive system

• Scavenger .• Depend on fallen and decaying vegetation. Digestive system:• Tubular and straight.• Mouth Pharynx crop gizzard calciferous

gland Anus• Typhlosole.

Gaseous exchange and Circulation• Respire through body wall. CIRCULATION• The blood system is a closed system.• Blood…..head to the tail in the ventral vessel tail to the head….. in the dorsal vessel• Photoreceptors are present

Nervous system

–Dorsal brain–Pair of nerves on sides of esophagus–Paired ventral nerve cords with paired

ganglia in each segment–Transverse nerves connect ganglia in

each segment

Excretion: Metanephridia

Reproduction:

• Monoecious. Sexual reproduction• Through copulation….. cocoon formation.

Asexual reproduction• Transverse division• Regeneration of parts