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3 Major Classes in Phylum Annelida . Class Oligochaeta: the earthwormsClass Hirudinea : The leechesClass Polycheata: The marine worms. . . . Annelida Taxonomy. Phylum Annelida (an-nel-i-da)Class Polychaeta (poly-key-ta)Nereis, Aphrodita, Chaetopterus, Arenicola, AmphitriteClass Oligochaeta (ol-e-go-key-ta)Lumbricus, TubifexClass Hirudinea (hi-ru-din-e-a)Hirudo, leech.
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1. Phylum AnnelidaAnnelus = “ Little Ring” The Segmented Worms
2. 3 Major Classes in Phylum Annelida
3. Annelida Taxonomy Phylum Annelida (an-nel-i-da)
Class Polychaeta (poly-key-ta)
Nereis, Aphrodita, Chaetopterus, Arenicola, Amphitrite
Class Oligochaeta (ol-e-go-key-ta)
Lumbricus, Tubifex
Class Hirudinea (hi-ru-din-e-a)
Hirudo, leech
4. Nereis (clam worm)
5. Aphrodite (sea mouse)
6. Other Polychaetes
7. Hirudo (leech)
8. Lumbricus
9. Identifying Characteristics of the Annelids Have a TRUE COELOM (body cavity which allows them to have true organ systems and muscular layers)
Possess complex digestive & circulatory systems as well as defined nervous and excretory systems
No developed respiratory system as they exchange O2 and CO2 via moist epidermis
Are segmented into a sequence of compartments by septa. Segments are marked by rings called annuli
Reproduce sexually and some asexually by regeneration and fission
Are hermaphroditic with cross fertilization
Are found in terrestrial, freshwater and marine environments
Can range in size from less than 1 mm to over 3 meters (the seep tube worm)
10. Example: The Earthworm- Digestive system is a one way tube including a mouth and anus with specialization of digestive organs (esophagus, crop, gizzard, and intestines)- Closed circulatory system with blood contained in blood vessels. Presence of a primitive heart and hemoglobin in the blood to carry O2
- Excretory system includes nephridia (primitive kidneys) which eliminate waste from the blood
- Nervous system includes cephalization with a primitive brain and ventral nerve cord. No defined sensory organs
11. Earthworm Reproduction Although earthworms are hermaphroditic (produce both eggs and sperm) they must still copulate in order to mix their gametes
Earthworms are also capable of re-growing amputated segments of their bodies
12. Ecological Importance of Annelids Form the base of many food chains
House parasites such as Protozoa, Platyhelminthes and Nematodes
Aerate & mix the soil and are constructive to mineralization and nutrient uptake by vegetation
Certain species mix the surface and mineral soil by traveling between the two
13. Biological Roles include:
acting as composters and helping to create dead organic matter into fertile soil
Chemical Roles include:
helping to cycle nutrients and minerals through the soil through their casts (worm poop!) Increase the levels of nitrogen, phosphates and potash
Physical Roles include:
burrowing and keeping the soil structure open (aerating the soil and providing a path for drainage)
14. Random Annelid Facts In the New Zealand Maori culture NOKE is an earthworm dish sold as a delicacy
Lumbriculus and Aulophorus (species of annelids) are known to reproduce by the penis breaking into fragments and then forming whole new worms!