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Chapter 33 The ANIMALS

Chapter 33 The ANIMALS. This is the big chapter…. Overview: Life Without a Backbone. Invertebrates are animals that lack a backbone They account for 95% of known animal species. Fig. 33-2. Cladogram of the animals…. Calcarea and Silicea. ANCESTRAL PROTIST. Cnidaria. Lophotrochozoa.

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Chapter 33 The ANIMALS

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  1. Chapter 33 The ANIMALS This is the big chapter…

  2. Overview: Life Without a Backbone • Invertebrates are animals that lack a backbone • They account for 95% of known animal species

  3. Fig. 33-2 Cladogram of the animals… Calcarea and Silicea ANCESTRAL PROTIST Cnidaria Lophotrochozoa Common ancestor of all animals Eumetazoa Ecdysozoa Bilateria Deuterostomia

  4. Fig. 33-3-1 Placozoa (1 species) Calcarea and Silicea (5,500 species) 0.5 mm A sponge Cnidaria (10,000 species) A placozoan (LM) Ctenophora (100 species) A jelly Acoela (400 species) A ctenophore, or comb jelly 1.5 mm Acoel flatworms (LM) LOPHOTROCHOZOANS Rotifera (1,800 species) Platyhelminthes (20,000 species) A marine flatworm A rotifer (LM) Ectoprocta (4,500 species) Brachiopoda (335 species) Ectoprocts A brachiopod

  5. Fig. 33-3-2 Cycliophora (1 species) Acanthocephala (1,100 species) 100 µm An acanthocephalan (LM) A cycliophoran (colorized SEM) Nemertea (900 species) Mollusca (93,000 species) An octopus Annelida (16,500 species) A ribbon worm A marine annelid ECDYSOZOA Loricifera (10 species) Priapula (16 species) 50 µm A loriciferan (LM) A priapulan

  6. Fig. 33-3-3 Tardigrada (800 species) Onychophora (110 species) 100 µm Tardigrades (colorized SEM) An onychophoran Nematoda (25,000 species) Arthropoda (1,000,000 species) A roundworm A scorpion (an arachnid) DEUTEROSTOMIA Hemichordata (85 species) An acorn worm Echinodermata (7,000 species) Chordata (52,000 species) A sea urchin A tunicate

  7. Fig. 33-3a A Sponge A sponge

  8. Fig. 33-3b A Cnidarian A jelly

  9. Fig. 33-3d A Ctenophore… A ctenophore, or comb jelly

  10. Fig. 33-3e Flatworms 1.5 mm Acoel flatworms )

  11. Fig. 33-3f Marine Flatworm… A marine flatworm

  12. Fig. 33-3g A Rotifer (in pond water) A rotifer (LM)

  13. Fig. 33-3h Ectoprocts Ectoprocts

  14. Fig. 33-3i Brachiopods A brachiopod

  15. Fig. 33-3l Ribbon Worm… (Yikes) A ribbon worm

  16. Fig. 33-3m Octo-mom (a mollusk) An octopus

  17. Fig. 33-3n Marine Annelid (earthworm cousin) A marine annelid

  18. Fig. 33-3q Tardigrades (water bears) 100 µm Tardigrades (colorized SEM)

  19. Fig. 33-3r These are thought to be the living Fossil of the ancestor to the arthropods An onychophoran

  20. Fig. 33-3s Roundworm… Nematoda A roundworm

  21. Fig. 33-3t The itsy bitsy spider? A scorpion (an arachnid)

  22. Fig. 33-3v Echinoderm… Sea urchin (related to sea stars..) A sea urchin

  23. Fig. 33-3w Tunicate (sea squirt)… ancestor to all chordates A tunicate

  24. Concept 33.1: Sponges are basal animals that lack true tissues • Sponges are sedentary animals from the phyla Calcarea and Silicea • They live in both fresh and marine waters • Sponges lack true tissues and organs

  25. Porifera details… • Sponges are suspension feeders, capturing food particles suspended in the water that pass through their body • Choanocytes, flagellated collar cells, generate a water current through the sponge and ingest suspended food • Water is drawn through pores into a cavity called the spongocoel, and out through an opening called the osculum

  26. Fig. 33-4 Food particles in mucus Flagellum Choanocyte Collar Choanocyte Osculum Azure vase sponge (Callyspongia plicifera) Spongocoel Phagocytosis of food particles Amoebocyte Pore Spicules Epidermis Water flow Amoebocytes Mesohyl

  27. Sponges consist of a noncellularmesohillayer between two cell layers • Amoebocytesare found in the mesohyl and play roles in digestion and structure • Most sponges are hermaphrodites: Each individual functions as both male and female

  28. Concept 33.2: Cnidarians are an ancient phylum of eumetazoans • All animals except sponges and a few other groups belong to the cladeEumetazoa, animals with true tissues • Phylum Cnidaria is one of the oldest groups in this clade

  29. Fig. 33-UN2 Calcarea and Silicea Cnidaria Lophotrochozoa Ecdysozoa Deuterostomia

  30. Cnidarians have diversified into a wide range of both sessile and motile forms including jellies, corals, and hydras • They exhibit a relatively simple diploblastic, radial body plan • The basic body plan of a cnidarian is a sac with a central digestive compartment, the gastrovascular cavity • A single opening functions as mouth and anus • There are two variations on the body plan: the sessile polyp and motile medusa

  31. Fig. 33-5 Polyp Medusa Mouth/anus Tentacle Polyp Medusa Gastrovascular cavity Gastrodermis Mesoglea Body stalk Epidermis Tentacle Mouth/anus

  32. Cnidarians are carnivores that use tentacles to capture prey • The tentacles are armed with cnidocytes, unique cells that function in defense and capture of prey • Nematocysts are specialized organelles within cnidocytes that eject a stinging thread

  33. Fig. 33-6 Tentacle Cuticle of prey Thread Nematocyst “Trigger” Thread discharges Thread (coiled) Cnidocyte

  34. Table 33-1

  35. Fig. 33-7 (d) Sea anemone (class Anthozoa) (b) Jellies (class Scyphozoa) (c) Sea wasp (class Cubozoa) (a) Colonial polyps (class Hydrozoa)

  36. Hydrozoans • Most hydrozoans alternate between polyp and medusa forms

  37. Fig. 33-8-3 Reproductive polyp Feeding polyp Medusa bud MEIOSIS Gonad Medusa Egg Sperm SEXUAL REPRODUCTION ASEXUAL REPRODUCTION (BUDDING) Portion of a colony of polyps FERTILIZATION Zygote Developing polyp 1 mm Planula (larva) Key Mature polyp Haploid (n) Diploid (2n)

  38. Scyphozoans • In the class Scyphozoa, jellies (medusae) are the prevalent form of the life cycle

  39. Anthozoans • Class Anthozoa includes the corals and sea anemones, which occur only as polyps • Corals are colonial anthozoans • Hard corals secrete Calcium Carbonate skeletons from the base. • Build “reefs” in shallow tropical seas. • Have mutualistic relations with algae living inside tissue. (Zooxanthellae) • -Paradox of the coral reef…?

  40. Flatworms • Members of phylum Platyhelminthes live in marine, freshwater, and damp terrestrial habitats • Although flatworms undergo triploblastic development, they are acoelomates • They are flattened dorsoventrally and have a gastrovascular cavity • Gas exchange takes place across the surface, and protonephridia regulate the osmotic balance

  41. Flatworms are divided into four classes: • Turbellaria (mostly free-living flatworms) • Monogenea (monogeneans) • Trematoda (trematodes, or flukes) • Cestoda (tapeworms)

  42. Table 33-2

  43. Planarians have light-sensitive eyespots and centralized nerve nets • The planarian nervous system is more complex and centralized than the nerve nets of cnidarians • Planarians are hermaphrodites and can reproduce sexually, or asexually through fission

  44. Fig. 33-10 Pharynx Gastrovascular cavity Mouth Eyespots Ganglia Ventral nerve cords

  45. Monogeneans and Trematodes • Monogeneans and trematodes live as parasites in or on other animals • They parasitize a wide range of hosts, and most have complex life cycles with alternating sexual and asexual stages • Trematodes that parasitize humans spend part of their lives in snail hosts • Most monogeneans are parasites of fish

  46. Fig. 33-11 Male Female Human host 1 mm Motile larva Ciliated larva Snail host

  47. Tapeworms • Tapeworms are parasites of vertebrates and lack a digestive system • Tapeworms absorb nutrients from the host’s intestine • Fertilized eggs, produced by sexual reproduction, leave the host’s body in feces

  48. Fig. 33-12 200 µm Proglottids with reproductive structures Hooks Sucker Scolex

  49. Brachiopods superficially resemble clams and other hinge-shelled molluscs, but the two halves of the shell are dorsal and ventral rather than lateral as in clams

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