1. Annelids

2. Phylum Annelida Class Aelosomata Class Polychaeta Class Clitellata
Marine worms
Subclass Errantia
Subclass Sedentaria
Subclass
Oligochaeta
Subclass
Hirudinae
earthworms
Leeches

3. Annelids Class Polychaeta marine worms segmented Class Clitellata
Subclass Oligochaeta
earthworms
Subclass Hirudinea
Leeches

4. Characteristics Segmentation (metameric body plan) Eucoelomate
15,000 species
Closed circulatory system, but no heart
Hydrostatic skeleton
Excretion- protonephridia, metanephridia, diffusion or gills
Simple gut
Respiration- diffusion or gills
Central nervous system- brain and nerve cord
Reproduction- asexual or sexual (many gonochoric)
Sensory system of tactile organs, taste buds, statocysts, photoreceptor cells, and eyes with lenses.

5. Subclass Oligochaeta Lack parapodia and have few setae
Lack the distinctive head region of polychaetes and have no eyes.
Scavengers that consume soil that contains organic matter
The ingested soil moves into a storage chamber called the crop, then to an area called the gizzard, where grinding action breaks down the soil particles. Undigested material passes out the anus in a form called castings, which are prized as soil fertilizer.

6. Each segment is also known as a metamere
Metamerism (segmentation)
Each segment is also known as a metamere
Each metamere has a parapodia with numerous setae
parapod
chaetae

7. Body Cavities Eucoelomate- body cavity completely lined with mesoderm
gut
Eucoelomate- body cavity completely lined with mesoderm
Ectoderm
Endoderm

8. Earthworm Phylum Annelida
Hydrostatic Skeleton
Earthworm Phylum Annelida

9. Closed Versus Open Circulatory Systems

10. Closed Circulatory System

11. Nervous System and Behavior
A mass of ganglia (neural masses) forms an anterior brain that is usually dorsal to the pharynx.
They have either a pair of ventral nerve cords (primitive) or a single ventral nerve cord that runs the length of the body.
Each segment has a swelling of the nerve cord called a segmental ganglion.
Sensory receptors include: chemoreceptors, touch receptors, photoreceptors, statocysts and vibration receptors.
Behaviors vary depending on class/life style.

12. Oligochaete Nervous System

13. Digestive System Esophagus Gizzard Pharynx Crop Intestine Mouth
Buccal cavity
Intestine
Mouth

14. Reproductive System Seminal vesicle Sperm duct Seminal receptacle
Ovary
Testes
Egg funnel
and oviduct
Seminal receptacle
Sperm duct

15. Oligochaete Reproduction

16. Oligochaete Excretory System

17. Subclass Hirudinea Leeches
Most live in fresh bodies of water, but some live among moist vegetation.
Suckers found on both ends
Unlike other annelids, its segments are not separated internally
Leeches lack both setae and parapodia
Most are predators or scavengers. Very few are parasites.
They secrete anticoagulants, hirudin, to keep blood from clotting and anesthetic that prevents the host from feeling their presence.

18. Subclass Hirudinea

19. Hirudo medicinalis

20. Class Polychaeta Largest group of annelids Primarily marine
Most segments include a pair of paddle–like parapodia
Well-developed head with eyes and other sensory structures

21. Class Polychaeta Subclass Sedentaria Fan worms, Christmas-tree worms
Spaghetti worms
Chaetopterus
lugworms
Subclass Errantia
Sand worms,
Scale worms
Fire worms
palolo worms

22. featherduster worms
Subclass Sedentaria

23. Lugworm
Subclass Sedentaria

24. Chaeopteris
Subclass Sedentaria

25. Spaghetti worm Lanice conchilega Subclass Sedentaria
Ancient Hawaiians called spaghetti worms kauna'oa or kio and used them as medicine (for what ailment is not clear).
Patients either drank an infusion of cooked tentacles daily for several weeks or sucked the body fluid from a live worm through a bamboo tube
Lanice conchilega
Hawaii has 11 species
5 are endemic
Subclass Sedentaria

26. Christmas tree worms
Spirobranchus giganteus
Subclass Sedentaria

27. Scale worm
Subclass Errantia

28. Fire worm
Eurythoe complanata
Subclass Errantia

29. The pharynx is everted by contraction of body wall muscles.

30. Parapodia- movement and respiration

31. Polychaete Trochophore Larvae

32. Polychaete Larvae (setiger)