Annelids.pptx
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Earthworms are segmented invertebrates that reproduce both asexually through regeneration and fragmentation, and sexually. They are hermaphroditic, containing both male and female organs, and fertilize their eggs internally before depositing them in cocoons. The cocoons hatch after 2-3 weeks to release 4 worms on average. Earthworms have a nervous system segmented along their body, with ganglia at each segment controlling that region, and various sensory receptors along their skin. They are scavengers that feed on dead organic matter in soil and pass nutrients through their digestive systems.
Annelids.pptx
- 1. Ex. Earthworms Segmented Invertebrates
- 2. Asexual: regeneration/fragmentation Fragmentation is a self-produced, mechanical breaking of the organism into two or more pieces, followed by regenerative growth of missing parts in each fragment.
- 3. Hermaphroditic: contain both female and male organs, produces both sperm & eggs exchange of sperm occurs between two worms Mature sperm and egg cells are deposited in cocoons produced by the clitellum ova (eggs) are fertilized by the sperm cells within the cocoon The cocoon slips off the worm and is deposited in or on the soil. The eggs hatch after about 3 weeks. http://edis.ifas.ufl.edu/IN047
- 4. Eggs hatch within 2-3 weeks if conditions are favorable An average of 4 worms are produced from each cocoon Worms can reproduce after 12 months
- 5. The nervous system of the earthworm is "segmented" just like the rest of the body. No true "brain" , but cerebral ganglia (dense bundles of nerves) are located at the anterior (head) end If these cerebral ganglia are removed, the earthworm will move continuously. Each segment has a ganglion which controls only that segment Earthworms have touch, light, vibration and chemical receptors all along the entire body surface.
- 6. Most earthworms are scavengers that feed on dead organic matter. nourishment is extracted from soil or leaves as they pass through the gut (digestive sys) Note: does not require highly developed sense organs (such as eyes, which would be of little use underground) or food-catching structures http://www.austmus.gov.au/factSheets/earthworms.htm
- 7. urea (a nitrogenous waste product) is excreted through long tubules called nephridia Part of these wastes are picked up from body tissues and the blood The urea is expelled through the pores of the nephridia Earthworms leave a trail of this expelled urea called casings which are full of nutrients
- 8. Circulation occurs through a series of closed vessels. The two main vessels, pumping structures, are the dorsal and ventral blood vessels. Although some say that they have 5 hearts, they are not true hearts. Capillary beds branch off the main vessels to pick up or release nutrients and, oxygen
- 9. 1st Food particles taken in by heterotrophs are broken down by digestive enzymes into smaller building blocks usually by hydrolysis reactions (breaking apart by H2O). Carbohydrates glucose Proteins amino acids Fats fatty acids, glycerol Nucleic acids nucleotides (n-base, sugar, phosphate)
- 10. 2nd These building blocks are then synthesized into the large molecules needed by the cell usually through dehydration reactions (linking together by the removal of H2O). Glucose + glucose carbohydrates Amino acid + amino acid proteins Fatty acids + glycerol fats, lipids Nucleotide + nucleotide nucleic acids
- 11. Moist skin is the respiratory organ of the earthworm Oxygen and carbon dioxide simply diffuse through the skin.