1 / 16

Phylum Annelida

Phylum Annelida. Leech. The Segmented Worms. Nereis. Earthworm. Are There Many Kinds of Annelids??. 15,000 species of annelids can be divided into three major groups. Polychaeta. Oligocheata. Hirudinea. What Are Annelids? General Characteristics. Bilateral symmetry

mccrays
Download Presentation

Phylum Annelida

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Phylum Annelida Leech The Segmented Worms Nereis Earthworm

  2. Are There Many Kinds of Annelids?? • 15,000 species of annelids can be divided into three major groups Polychaeta Oligocheata Hirudinea

  3. What Are Annelids?General Characteristics • Bilateral symmetry • Definate anterior / posterior ends • Distinguishable dorsal / ventral side • True tissue / organ level of organization • Segmented bodies • The distinguishing feature of all annelids • Annelida = “little rings” • Range in size • < 1mm up to 3 meters!! • Eg. giant Australian earthworm

  4. The Internal Structure of Annelids • Complete digestive tract • Several specialized regions • Circulatory system • Closed vessels • Blood containing hemoglobin • Nervous system • Brain-like structure • Reproductive structures • Ovaries and testes

  5. All Annelids AreCoelomates . . . • They have a true body cavity • Coelom is lined with mesoderm cell layer • “Tube-within-a-tube” body plan • Outside tube • Body wall • Inside tube • Digestive tract

  6. Annelids are the simplest animals to have a true coelom!

  7. What happens to the “stuff” annelids eat?!? • Specialized regions aid in digesting the organic matter in soils ingested • CROP • Temporarily stores food • GIZZARD • Thick walled organ which grinds food

  8. Nereis . . . The Hunter Tentacles • Marine Sandworm • Found at tide level • Carnivorous • Feeds on small animals • Distinct anterior segment • Prostomium • 2 short tentacles + 2 palps • 2 pairs of small eyes • Peristomium • 4 pairs of tentacles surrounding mouth Figure 32-14, Pg. 698 Palps

  9. How does the pharynx work?? • The pharynx is extended out of the mouth • Pointed claw-like jaws capture prey • Pharynx pulls food back through mouth • Food moves into intestine where digestion begins Pharynx Jaw

  10. These Guys Can Move! Parapodia • Nereis have structures allowing them to swim AND creep over sand • Parapodia • Paddle-like extensions • Setae • Bristle-like structures Setae

  11. Reproduction in Annelids • Oligochaeta & Hurudinea • Hermaphrodites • Cross-fertilization • Internal fertilization • Polycheata • Separate sexes • External fertilization • Gametes are released through excretory organs • Free-swimming larva

  12. Earthworms Create a Cocoon! Clitellum : sperm are stored temporarily until a mucus cocoon is created to protect the fertilized eggs!

  13. Leeches: the ecto-parasite! • Feed on the blood of their prey • Hirudin • Enzyme which prevents blood clotting • The jaws break through the host’s skin • Blade-like jaws make incision

  14. Two Evolutionary Innovations • The presence of a true coelom • Provides support • Acts as a hydrostatic skeleton • Room for organ development • Advancements in locomotion • Not the dance!!!! . . . Motility!!! • Segmentation of the body • Specialization of body regions • Feeding and sensory input, motility • Modification of various segments for different functions

  15. Worms today. . . Mollusks tomorrow! Until then . . . Be kind to your neighborly annelid . . . You may depend on one someday!

More Related