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Chapter 33

Chapter 33. Sponges Cnidarians Ctenophores. Objectives. Describe: the basic body plan of a sponge Describe: the process of filter feeding in sponges Contrast: the process of sexual and asexual reproduction in sponges. Sponge Sessile Choanocyte Ostium Osculum Spongin. Spicule

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Chapter 33

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  1. Chapter 33 Sponges Cnidarians Ctenophores

  2. Objectives • Describe: the basic body plan of a sponge • Describe: the process of filter feeding in sponges • Contrast: the process of sexual and asexual reproduction in sponges

  3. Sponge Sessile Choanocyte Ostium Osculum Spongin Spicule Filter feeding Amoebocyte Gemmule Regeneration Hermaphrodite Vocabulary

  4. Porifera Comes from the Latin word meaning “pore-bearer” Sponge an aquatic invertebrate of the phylum Porifera that attaches to stones or plants and that has a porous structure and a tough, elastic skeleton Vocabulary

  5. Sessile describes an organism that remains attached to a surface for its entire life and does not move Choanocyte any of the flagellate cells that line the cavities of a sponge Vocabulary

  6. Ostium one of the small openings in a sponge’s body through which water enters Osculum an opening in a sponge's body through which water exits Vocabulary

  7. Spongin a fibrous protein that contains sulfur and composes the fibers of the skeleton of some sponges Spicule a needle of silica or calcium carbonate in the skeleton of some sponges Vocabulary

  8. Filter Feeding in an aquatic animal, a method of feeding in which the animal traps organic material that is floating in the surrounding water Amoebocyte in sponges and other invertebrates, an amoeba-like cell that moves through the body fluids, removes wastes, and participates in other processes Vocabulary

  9. Gemmule an asexual reproductive structure produced by some freshwater sponges Regeneration The re-growth of missing tissues or organs Amoebocyte

  10. Hermaphrodite an organism that has both male and female reproductive organs Vocabulary

  11. Body Plan of Sponges • The phylum Porifera is made up of sponges. • Sponges are sessile invertebrates that have no true tissues or organs. The simplest sponges are shaped like hollow cylinders.

  12. Body Plan of Sponges • The body wall of a sponge is composed of two layers of cells that are separated by a jellylike substance called mesohyl. • Choanocytes in the interior layer draw water through the ostia that penetrate the body wall. The water leaves through the osculum. • The body is supported by a skeleton made of spongin, spicules, or both.

  13. Sponge Structure

  14. Feeding and Digestion in Sponges • Sponges feed by filtering small organisms and organic matter out of the water that passes through their body. This is called filter feeding. • Nutrients are distributed through the body by amoebocytes, cells which crawl about within the body wall.

  15. Sponge Reproduction • Sponges can reproduce both asexually and sexually. • They reproduce asexually through: • producing buds or gemmules • regeneration of missing parts

  16. Sponge Reproduction • They reproduce sexually through the joining of egg and sperm. • Most sponges are hermaphrodites, which can produce both eggs and sperm.

  17. Sponge Reproduction

  18. Cnidaria and Ctenophora • Cnidaria (nie-DER-ee-uh) • Ctenophora (tee-NAHF-uhr-uh)

  19. Examples of Cnidarians • Freshwater Hydra • Stinging Jellyfish • Flowerlike Coral

  20. Body Plan of Cnidarians • Animals in the phylum Cnidaria are radially symmetrical aquatic invertebrates that are more complex than the sponges. • They have tissues and a few simple organs.

  21. Body Plan of Cnidarians • The cnidairan body is either a sessile polyp or a swimming medusa. • Some cnidarians alternate between both types during their life cycles.

  22. Body Plan of Cnidarians • The body of a cnidarian consists of two cell layers: • an outer epidermis • an inner gastrodermis • The layers are separated by the mesoglea.

  23. Body Plan of Cnidarians • The gastrovascular cavity has a single opening (the mouth) surrounded by tentacles.

  24. Feeding and defense in Cnidarians • Cnidarians have cells called cnidocytes. • Each cnidocyte contains a nematocyst. • When a cnidocyte is stimulated, its nematocyst ejects a filament that can paralyze or ensnare prey.

  25. Nervous System in Cnidarians • The cnidarian nervous system is a diffuse web of interconnected nerve cells called a nerve net.

  26. Classes of Cnidaria • Class Hydrozoa • This class includes Obelia, man-o-war, and the hydra. • Hydrozoans may live as polyps, medusae, or mixed colonies. • Pic. Of Portugese Man-o-war.

  27. Reproduction of Obelia

  28. Classes of Cnidaria • Class Cubozoa • This class includes box jellies. • Cubozoans spend most of their lives as medusae. • Pic. of Box Jellyfish

  29. Classes of Cnidaria • Class Scyphozoa • This class includes jellyfish. • Scyphozoans spend most of their lives as medusae.

  30. Reproduction in Aurelia

  31. Classes of Cnidaria • Class Anthozoa • This class includes sea anemones and corals. • Anthozoans live only as polyps. • Brain Coral

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