Chapter 8 Lower Invertebrates

1. Chapter 8 Lower Invertebrates

2. What Are Animals? • Animals: • are multicellular • have eukaryotic cells without cell walls • cannot produce their own food, depend on other organisms for nutrients • can actively move • invertebrates = animals that lack a vertebral column (backbone) • vertebrates – animals with a vertebral column • majority of animals in sea are invertebrates

3. Body Structure • Dorsal – Top • Ventral – Bottom/belly • Anterior – Head • Posterior - Tail

4. Body Symmetry • Asymmetry – No symmetry • Radial – Arrangement of body parts around a central axis - Top & bottom, No front, back, or right & left sides – Allows for organism to take in stimuli from all sides

5. Bilateral symmetry – 2 similar halves on either side of a central plane • Adaptation for movement

6. Cephalization • Concentration of sensory & brain structures in the Anterior region No-cephalization

7. Sponges • Phylum Porifera • Basic characteristics: • Simple • Asymmetric • Sessile: Permanently attached to a solid surface • Have many shapes, sizes and colors • Shape often determined by shape of bottom sediments, material on which they are growing and local water currents

8. Sponges have specialized Cells but NOTissues • Most primitive animals on Earth

9. Sponge Structure and Function • Body is built around a system of water canals • Ostia: Tiny holes or pores through which water enters the sponge’s body • Spongocoel: Spacious cavity in the sponge into which water flows • Osculum: Large opening through which water exits from the spongocoel

10. Sponge Structure and Function • Lacking tissues, sponges have specialized cells • Collar cells (Choanocytes) use their flagella to provide force for moving water through the sponge’s body • Amoebocytes: Cells that resemble amoebas, and can move through sponge body • Transport materials

11. Sponge Structure and Function • Structural materials • Spicules: Skeletal elements that give support to a sponge’s body, produced by specialized cells and composed of calcium carbonate, silica or spongin • Spongin: A protein that forms flexible fibers

12. Sponge Structure and Function • Sponge size and body form • Size is limited by water circulation • Asconoid: Simplest form; tubular and always small, found in clusters • Syconoid: Sponges that exhibit the first stages of body-wall folding • Leuconoid: Sponges with the highest degree of folding, which have many chambers lined with collar cells

13. Osculum Ostia Choanocyte Spicules Amoebocyte

14. Sponge Structure and Function • Nutrition and digestion • Sponges are suspension feeders – feed on material suspended in seawater • Sponges are also referred to as Filter Feeders – they filter food from the water • Large particles are engulfed and digested by pinocytes and archaeocytes • Collar cells trap ~ 80% of food which consists of small particles (0.1 to 1.0 micrometers in size) • Sponges are one of the few animals that can capture such small sized particles

15. Sponge Structure and Function • Reproduction in sponges • Asexual reproduction • Budding: Group of cells on the outer surface of the sponge develops and grows into a tiny new sponge, which drops off and establishes itself • Fragmentation: Production of a new sponge from pieces that are broken off by physical processes, e.g., waves, storms, predators • Sexual reproduction • Most sponges are Hermaphrodites • Larval stage is called a planktonic Amphiblastula

16. Ecological Roles of Sponges • Competition • Compete aggressively with corals and bryozoans for attachment space • Predator-prey relationships • Few species eat sponges • Spicules are like needles • Some produce chemical deterrents • A few species of bony fish and molluscs and sea turtles (especially the hawksbill) will eat sponges

17. Ecological Roles of Sponges • Symbiotic relationships • Sponges are Mutualistic or Commensalistic hosts to many organisms • e.g. symbiotic cyanobacteria • Many organisms (shrimp, fish) live within the canals or spongocoel, for protection and to take advantage of water flow

18. Ecological Roles of Sponges • Sponges and nutrient cycling • Boring sponges (family Clionidae) recycle calcium as they burrow into coral and mollusc shells

19. http://www.youtube.com/watch?v=8ueKlShb9Ls Sponge Dye in the Ocean

20. Kingdom: Animalia Phylum: Cnidaria Jellyfish, Anemone, Corals

21. Cnidarians: Animals with Stinging Cells • Phylum Cnidaria • Include jellyfish, hydroids, corals and sea anemones • Named for their Cnidocytes—Stinging cells • Cnidocytes are used to capture prey and protect the animal

22. Organization of the Cnidarian Body • Often exhibit 2 body plans within their life cycles: • Polyp: Benthic form characterized by a cylindrical body with an opening at 1 end, i.e., the mouth which is surrounded by tentacles • Medusa: A free-floating stage (jellyfish)

23. Stinging Cells • Cnida: Stinging organelle within a cnidocyte, which may function in locomotion, prey capture, or defense • Nematocysts: Spearing type cnida, which are discharged when the cnidocill—a bristle-like trigger—contacts another object

24. Stinging Cells • Stinging cells also triggered by certain chemical substances released by prey • Dangerous species • Box jellyfish (can kill within 3-20 minutes)

25. Kingdom: AnimaliaPhylum: Cnidaria Class: Hydrozoa “water animals”

26. Types of Cnidarians • Hydrozoans (class Hydrozoa) • Mostly colonial • Colonial forms contain 2 types of polyp: • Gastrozooid = Feeding polyp • Gonangium = Reproductive polyp • Hydrozoans known as hydrocorals secrete a calcareous skeleton, e.g., fire coral • Some produce floating colonies • e.g. Portuguese man-of-war

27. http://www.youtube.com/watch?v=xTgLTbXJrfM&list=PL355D512277EFFA06&index=23http://www.youtube.com/watch?v=xTgLTbXJrfM&list=PL355D512277EFFA06&index=23 Portuguese Man of War

28. Colonyof medusae and polyps Gas-filled float: Tentacles measure up to 65ft Preys mostly on small fish-poison can be painful and even fatal to humans Ex: Physalia Portuguese man-of-war

29. Phylum: Cnidaria Class: Scyphozoa “cup animals” True Jellyfish

30. Cup animals Jellyfish Medusais the dominant form of the life cycle Pulsating motions of the cup propel the jellyfish through the water Some nematocysts cause severe pain and even death to humans Phylum: CnidariaClass: Scyphozoa

31. Types of Cnidarians • Jellyfish • Scyphozoans—True jellyfish (class Scyphozoa) • Considered members of the plankton • Medusa is predominant life stage • Photoreceptors: Sense organs that can determine whether it is dark or light • Box jellyfish (class Cubozoa) • Box-shaped bells • Relatively strong swimmers • Tropical • Voracious predators, primarily of fish

32. Phylum: Cnidaria Class: Anthozoa “flower animals” Sea Anemone & Coral

33. Types of Cnidarians • Anthozoans (class Anthozoa) • Include sea anemones, corals and gorgonians • Sea anemones • Benthic, all adults are sessile • Though sessile, many can change locations

34. Phylum: CnidariaClass: Anthozoa • “Flower Animals” • Polyp form dominant • Sea Anemone 1. Attach themselves to rocks and other submerged objects 2. Feed on fishes and other animals

35. Corals 1. Small polyps live in colonies 2. calcium carbonate skeleton 3. 30 degrees N or S of the equator 4. Shallow depths in warm, clear water 5. Zooxanthellae

36. Types of Cnidarians • Anthozoans (class Anthozoa) • Coral animals • Polyps that secrete a hard or soft skeleton • Hard, stony corals • Form reefs along with coralline red algae and calcified green algae

37. Types of Cnidarians • Anthozoans (class Anthozoa) • Soft corals • Polyps that form plant-like colonies

38. Nutrition and Digestion • Gastrovascular cavity: Central cavity where cnidarians digest their prey • Waste products forced back out mouth • Many hydrozoans and anthozoans are suspension feeders • Jellyfish and box jellyfish are carnivorous, eat fish and larger invertebrates • Sea anemones generally feed on invertebrates, some large species feed on fish, shallow water species have symbiotic algae

39. Reproduction • Scyphozoans • in adult jellyfish and box jellyfish, sexes generally separate • medusae (sexual stage) release gametes into the water column for fertilization • planula larvae settle, grow into polyps, and reproduce medusa-like buds asexually • immature buds are released into the water column to grow into mature medusae

40. Ecological Relationships of Cnidarians • Predator-prey relationships • Cnidarians are predators • Sea turtles, some fish and molluscs prey on hydrozoans and jellyfish

41. Ecological Relationships of Cnidarians • Symbiotic relationships • Portuguese man-of-war and man-of-war fish • Reef-forming corals and zooxanthellae • Algae provide food and oxygen to coral through photosynthesis • Coral provides nutrients and carbon dioxide to algae through respiration • Sea anemones... • and Clownfish • and the Hermit crab

42. Phylum: Ctenophora Comb jellies

43. Ctenophores • Phylum Ctenophora • Planktonic, nearly transparent • Ctenophore structure • Named for 8 rows of comb plates which the animal uses for locomotion • Are composed of large cilia • Exhibit radial symmetry • Lack stinging cells – Adhesive cells (sticky) • Bioluminescent

44. Comb jelly - eight comb likerows of cilia Move through water by beating their cilia Colloblasts-secrete a sticky substance that binds to their prey Apical organ-senses orientation in the water Most hermaphroditic Bioluminescence-production of light Occur in large swarms near the surface of the ocean Phylum: Ctenophora

45. http://www.youtube.com/watch?v=39qe0EajbIA&list=PL355D512277EFFA06&index=106http://www.youtube.com/watch?v=39qe0EajbIA&list=PL355D512277EFFA06&index=106 Neon Killers

46. The Evolution Of Bilateral Symmetry • Bilateral symmetry • Body parts arranged such that only one plane through the mid-line divides animal into similar right and left halves • Allowed for streamline body shape increasing mobility • Favored concentration of sense organs at one end of animal (Cephalization)

47. Flatworms • Have flattened, bilaterally symmetrical bodies with a definite head and posterior end

48. Flatworms • Types of Flatworm • Turbellarians are mostly pelagic, and are invertebrates living between sediment particles • Turbellarians have sensory receptors in head region to detect light, chemicals, movement and help maintain balance • Flukes usually have complex life cycles • Tapeworms live in the host’s digestive tract

49. Flatworms • Ecological role of flatworms • Turbellarians: • Turbellarians funnel nutrients to higher trophic levels • Prey for higher-level consumers • Parasitic flatworms: • Can regulate population size by lowering fitness of host

50. Ribbon Worms • Phylum Nemertea • Most are benthic • Resemble flatworms but are longer with thicker bodies • Sexes are separate, fertilization external • Carnivorous – Feed on annelids and crustaceans • Capture prey with proboscis (tube extending from mouth)