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ZOO 115 Invertebrate Zoology

ZOO 115 Invertebrate Zoology. Phylum Annelida Class Clitellata Subclass Oligochaeta. http://www.ahc.gov.au/publications/pnh/images/ea10597.jpg. Subclass Oligochaeta - General Characteristics. > 3500 species Most terrestrial or freshwater but about 200 marine species Includes earthworms

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ZOO 115 Invertebrate Zoology

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  1. ZOO 115 Invertebrate Zoology Phylum Annelida Class Clitellata Subclass Oligochaeta

  2. http://www.ahc.gov.au/publications/pnh/images/ea10597.jpg Subclass Oligochaeta - General Characteristics • > 3500 species • Most terrestrial or freshwater but about 200 marine species • Includes earthworms • 3m Australian earthworm

  3. Retractor muscle http://www.infovisual.info/02/img_en/007%20Internal%20anatomy%20earthworm%20cross.jpg Protractor muscle Subclass Oligochaeta - General Characteristics • They have few chaetae • Usually simple with typically four bundles per segment. • retractable

  4. http://www.howe.k12.ok.us/~jimaskew/botzo/wormx.gif Subclass Oligochaeta - external anatomy

  5. Subclass Oligochaeta - locomotion • Like Polychaetes - have septae separating segments into compartments making peristalsis more efficient. • Musculature similar to Polychaetes • During dry seasons and winters, earthworms burrow deeper (up to 3m) • Become dormant (diapause) and dehydrated

  6. Brain Ventral Nerve Cord Subclass Oligochaeta - Nervous system Chemosensory tubercles - form three rings on each segment - more concentrated in prostomium Mechanoreceptors on each segment - more concentrated in prostomium Photoreceptors on each segment - more concentrated in prostomium

  7. Segmental nerves - attach to longitudinal muscles Brain Contains 5 giant axons Ventral Nerve Cord Subclass Oligochaeta - Nervous system How do you think this animal responds to a sudden stimulus?

  8. http://www.miramar.sdccd.net/programs/biol/earthworm/ Subclass Oligochaeta - Feeding and Digestion • Muscular pharynx • Suction • Adhesion in some aquatic sp. • Pharyngeal glands - digestion • Scavengers • Deposit feeders

  9. Crop • Only in Earthworms • Used for storage • Gizzard • Chiton lined • Muscular • Grinding • Intestine http://www.emc.maricopa.edu/faculty/farabee/BIOBK/BioBookDiversity_8.html • Typhosole • - fold in intestine to increase surface area http://www.miramar.sdccd.net/programs/biol/earthworm/ http://www.emc.maricopa.edu/faculty/farabee/BIOBK/BioBookDiversity_8.html Subclass Oligochaeta - Feeding and Digestion

  10. Contractile Dorsal blood vessel http://www.backyardnature.net/pix/earthwm1.gif Blood Flow Subclass Oligochaeta - Circulatory system • Similar to other Annelids • Many have multiple hearts

  11. emc.maricopa.edu/faculty/farabee/BIOBK/BioBookDiversity_8.htmlemc.maricopa.edu/faculty/farabee/BIOBK/BioBookDiversity_8.html Subclass Oligochaeta - Excretion • Metanephridia • Usually one pair per segment

  12. Subclass Oligochaeta - Respiration • Mostly by diffusion through the body wall • A few species have gills • Aquatic tolerate low oxygen

  13. http://www.backyardnature.net/pix/earthwm1.gif Subclass Oligochaeta - Respiration • Calciferous glands • Secrete Calcium Carbonate • Function not entirely known. • Thought to play a role in CO2 removal

  14. Male reproductive organs Female reproductive organs Clitellum http://images.encarta.msn.com/xrefmedia/aencmed/targets/illus/ilt/T013733A.gif Subclass Oligochaeta - Reproduction • Sexual • Hermaphrodites • Copulation • Breed continuously • Genital Chaetae hold the worms together • In common earthworms, the gonopores don’t line up and the sperm have to swim • Asexual - common in aquatic species

  15. Clitellum http://images.encarta.msn.com/xrefmedia/aencmed/targets/illus/ilt/T013733A.gif Subclass Oligochaeta - Reproduction • Clitellum • Often most pronounced during mating period • Creates mucus for copulation • Works in conjunction with special muscles to create slippery furrows for swimming sperm in earthworms • Creates a cocoon for the eggs • Direct Development • 12 weeks to hatch • Can live several years

  16. Burrowing aerates the soil to provide air and water for plants Reduces runoff and surface evaporation of water Encourage growth of other organisms that have a detrimental effect on Nematodes Earthworms importance to Agriculture

  17. Digestion of organic material Per acre per year on cultivated land, 16,000 pounds (7200 kg) of soil pass through earthworm guts and are deposited atop the soil -- 30,000 pounds Fecal material (castings) Rich in nutrients. High in Nitrogen, Magnesium, Phosphorus, Calcium, Potash Neutralizes pH. Earthworms importance to Agriculture

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