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Phylum Annelida

Phylum Annelida. Segmented worms. Introduction to Phylum Annelida. Phylum Annelida is composed of segmented worms. Worms having a body divided into many sections. The name Annelida actually means “little rings”. Introduction to Annelida. Marine Fireworm. Leech. Earthworm.

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Phylum Annelida

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  1. Phylum Annelida Segmented worms

  2. Introduction to Phylum Annelida Phylum Annelida is composed of segmented worms. Worms having a body divided into many sections. The name Annelida actually means “little rings”

  3. Introduction to Annelida Marine Fireworm Leech Earthworm The 9,000+ species of annelids include earthworms, leeches, and a variety of marine worms.

  4. Introduction to Annelida About two-thirds of all annelids are marine organisms. Others are found in fresh water, and some are terrestrial.

  5. Introduction to Annelida Flatworm Roundworms Earthworms Annelids and Nematodes evolved around the same time from platyhelminthes and were the first animals to have a true coelom.

  6. Introduction to Annelida Formed entirely within the mesoderm, this kind of body cavity results in complex organs.

  7. Introduction to Annelida Coelomate animals are found at the top of the phylogenetic tree of animals. All are considered complex animals, but realize some are more advanced than others.

  8. Introduction to Annelida • Annelids were the first animals on Earth to have a body divided into segments. • Segmentation enables two main things: • Greater range of motion – the body is flexible • Improved body functions, or more specialization

  9. Introduction to Annelida Mollusks are not segmented animals, but all other coelomate animals are. Zoologists say that segmentation underlies the body plan of all higher coelomate animals.

  10. Introduction to Annelida Another innovation that appeared during annelid evolution was paired appendages Many of the marine annelids have a pair of fleshy lobes, called parapodia, that project from each segment

  11. Introduction to Annelida These appendages function as swimming paddles and sites of oxygen exchange. Many zoologists believe that parapodia are the beginnings of legs.

  12. Introduction to Annelida All the organ systems are present in annelids. The organs are suspended in the coelom by sheets of tissue

  13. Introduction to Annelida Another feature of annelids is the short bristles called setae on the body segments of most annelids. These tiny structures act as anchors and gripping devices. The number of setae on the bodies of annelids or the absence of setae is a characteristic used to divide the phylum into classes

  14. Setae

  15. Classes of Annelids • The three main classes of Annelids are: • Class Polychaeta • Mostly marine forms with many bristles and usually brightly colored. • Chris Tree is an example

  16. Classes of Annelids • Class Oligochaeta • Mostly freshwater or terrestrial forms with few bristles. • Earthworms are examples

  17. Classes of Annelids • Class Hirudinea • No bristles • Leeches are examples

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