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Phylum Annelida

Phylum Annelida. Segmented Worms Earthworm. Characteristics of Annelids. Earthworms are the most highly developed worms. They are divided into segments or parts. They are found in salt and fresh water as well as in the soil. Characteristics of Annelids.

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Phylum Annelida

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  1. Phylum Annelida Segmented Worms Earthworm

  2. Characteristics of Annelids • Earthworms are the most highly developed worms. • They are divided into segments or parts. • They are found in salt and fresh water as well as in the soil.

  3. Characteristics of Annelids • Earthworms are helpful to man as bait for fishing and more importantly, because they loosen the soil for roots to grow. • There are 2700 species of earthworms.  • A earthworm is generally earthtones such as brown, tan, etc. It can be up to eight feet in length!

  4. Body Cavity • Coelomate

  5. Muscular-Skeletal • A earthworm does not have a skeleton. It has bristles on each segment called setae that help the earthworm move. • Rear Anchor→ Elongation → Front Anchor→ Pull

  6. Muscular-Skeletal • The earthworm has two sets of muscles; one that makes it long and thin and one that makes it shorter and fatter.

  7. Digestion • A earthworm has a digestive system. It eats dirt, digesting the plant and animal matter in the dirt and then eliminates the rest. - mouth takes in food • a pharynx throat of earthworm, • A esophagus to pass food to crop • a crop to store the food in, • a gizzard that grinds the food down, • intestines for the food to pass through and take out nutrients • an anus for the food to come out.

  8. Digestion (cont.)

  9. Virtual Worm – Digestion • worm systems

  10. Nervous System • A earthworm has a nervous system with a simple brain and ventral nerve cord.

  11. Circulation • A earthworm has blood and blood vessels with multiple (5) hearts.

  12. Respiration • A earthworm has no respiratory organ. It takes in oxygen directly through its skin and gives off carbon dioxide. Its skin is always moist.

  13. Reproduction • A earthworm has both sperm and eggs within its body and reproduces sexually. However, the eggs must be fertilized by the sperm of another worm.

  14. Reproduction (cont.) • Earthworms are hermaphrodites with complex male and female reproductive organs present in each individual, but they cross fertilize.  • Two earthworms mate by attaching at their clitella and exchanging sperm, and then they separate. 

  15. Reproduction (cont.) • The received sperm are temporarily stored in sperm receptacles while the clitellum secretes a mucous cocoon.  • The cocoon slides along the worm, picking up the eggs which are produced in ovaries and then the stored sperm from special reproductive pores and then slips off the worm's head. • The embryos develop within the cocoon.

  16. Mating of 2 Earthworms

  17. Reproduction

  18. Excretion • A earthworm's wastes help to fertilize the soil. It gets rid of its wastes through tubes called nephridia that lead to pores that allow the wastes out.

  19. Symmetry • A earthworm has bilateral symmetry.

  20. Helpful Earthworms! • Did you know that Earthworms are a gardeners best friend? • Earthworms… • Break up/aerate soil • Helps water flow in soil • Worm feces contain bacteria that help return N to soil

  21. Parasitic Annelids???? Yep…you guessed it… LEECHES!

  22. Fun with Leeches! • Leech Facts: • There are 650 known species of leeches. • The largest leech discovered measured 18 inches. • The leech has 32 brains - 31 more than a human. • Not all leeches are bloodsuckers. Many are predators which eat earthworms, etc. • The bite of a leech is painless, due to its own anaesthetic. • The Hirudo leech injects an anti-coagulant serum into the victim to prevent the blood clotting.

  23. More leech facts • The leech will gorge itself until it has had its fill and then just fall off. • The leech will gorge itself up to five times its body weight. • The first leech was used in medicine about 1000 B.C., probably in ancient India. • The nearest relatives of leeches are earthworms. • Leeches can bite through a hippo's hide!

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