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Chapter 28

Chapter 28. An Introduction to Animal Diversity. Characteristics of Most Animals. 1. multicellular eukaryotes 2. cell specialization (cells  tissues  organs) 3. heterotrophs 4. locomotion (sometime in lifecycle) 5. nervous + muscle systems (stimuli) 6. sexual reproduction

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Chapter 28

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  1. Chapter 28 An Introduction to Animal Diversity

  2. Characteristics of Most Animals • 1. multicellular eukaryotes • 2. cell specialization • (cells  tissues  organs) • 3. heterotrophs • 4. locomotion (sometime in lifecycle) • 5. nervous + muscle systems (stimuli) • 6. sexual reproduction • (large, nonmotile eggs; flagellated sperm)

  3. Marine Environments • Advantages • Buoyancy – support • Temperature – stable • Fluid + salt balance easily maintained • Challenges • Water movement/currents • Adapt: • Strong swimmer – squid, fish, mammals • Sessile • Burrow in sand/silt • Small body size  plankton (food supply around as tossed)

  4. Other environments - problems • Fresh water • Water hypotonic to animal fluids  • Osmoregulation - pump out water, keep salts (ATP) • Less constant • Less food • Oxygen and temp. vary • Turbidity + water volume change

  5. Land • Desiccation • Adapt: body covering; respiratory surface deep within animal • Reproduction (desiccation) • Adapt: internal fertilization; shells on eggs; embryo in mom • Temperature extremes

  6. Body Symmetry • 2 types • Radial • wheel or cylinder form • Spokes from central axis • Cnidarians – jellyfish, sea anemones • Echinoderms – sea stars • Bilateral • Right and left halves – mirror images

  7. Fig. 32-7 (a) Radial symmetry (b) Bilateral symmetry

  8. Types of Body Cavities • Coelom = fluid-filled space between body wall and digestive tube • Acoelomate • No body cavity • Pseudocoelomate • Body cavity, not lined with mesoderm • Coelomate • Body cavity completely lined

  9. Fig. 32-2-3 Blastocoel Endoderm Cleavage Cleavage Blastula Ectoderm Archenteron Eight-cell stage Zygote Gastrulation Gastrula Blastocoel Blastopore Cross section of blastula

  10. Fig. 32-8 Coelom Body covering (from ectoderm) Tissue layer lining coelom and suspending internal organs (from mesoderm) Digestive tract (from endoderm) (a) Coelomate Body covering (from ectoderm) Pseudocoelom Muscle layer (from mesoderm) Digestive tract (from endoderm) (b) Pseudocoelomate Body covering (from ectoderm) Tissue- filled region (from mesoderm) Wall of digestive cavity (from endoderm) (c) Acoelomate

  11. 2 Main Groups of Coelomates • Protostomes • “first, the mouth” • Mollusks, annelids, arthropods • Deuterostomes • “second, the mouth” • Echinoderms, chordates

  12. Protostomes Spiral Deuterostomes radial Protostomes vs. DeuterostomesCleavage

  13. Fig. 32-9a Deuterostome development (examples: echinoderms, chordates) Protostome development (examples: molluscs, annelids) (a) Cleavage Eight-cell stage Eight-cell stage Spiral and determinate Radial and indeterminate

  14. Protostomes “determinate” cleavage Fixed early Can only become certain cell types Deuterostomes “indeterminate” cleavage Can adapt to become another cell type Protostomes vs. DeuterostomesDevelopmental Fate of the Embryo

  15. Fig. 32-9b Protostome development (examples: molluscs, annelids) Deuterostome development (examples: echinoderms, chordates) (b) Coelom formation Coelom Key Ectoderm Archenteron Mesoderm Endoderm Coelom Blastopore Mesoderm Blastopore Mesoderm Solid masses of mesoderm split and form coelom. Folds of archenteron form coelom.

  16. Protostomes Develops into the mouth Deuterostomes Develops into the anus Later, 2nd opening makes mouth Protostomes vs. DeuterostomesBlastopore = (opening from outside to gut)

  17. Fig. 32-9c Protostome development (examples: molluscs, annelids) Deuterostome development (examples: echinoderms, chordates) (c) Fate of the blastopore Anus Mouth Key Ectoderm Digestive tube Mesoderm Endoderm Anus Mouth Mouth develops from blastopore. Anus develops from blastopore.

  18. Sponges – Phylum Porifera • “to have pores” • Bodies – tiny holes • Marine

  19. Fig. 33-3a A sponge

  20. 3 main classes of sponges • Calcarea • Chalky, calcium carbonate spikes (spicules) • Hexactinellida (glass sponges) • 6-rayed spicules with silica • Demospongiae • Variable • Fibrous protein = spongin • Silica • OR spongin + silica

  21. 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

  22. Sponge Anatomy • Spongocoel • Central cavity – water flows • Ostia • Tiny pores, water enters • Osculum • Open end, water exits • Epidermal cells • Outer layer, line canals

  23. Sponge Anatomy • Canals • SA – food capture • Porocytes • Tube like cells – form pores • Regulate diameter by contracting • Collar cells

  24. Sponge Anatomy • Collar cells • Inner layer • Create water current, bring food and water to cells, carries away waste and CO2 • Trap and phagocytize food • Tiny collar at base of flagellum

  25. Sponge Anatomy • Mesohyl • Gelatin-like layer • Between inner and outer layers of sponge body • Amoebocytes • In mesohyl • Digestion, food transport, secrete spicules

  26. Sponge Feeding • Suspension feeders • Trap + eat whatever food the water brings • Water circulates in body • Food trapped on sticky collars of choanocytes • Food digested in collar or amoeboid cell • Undigested – out to water through osculum

  27. Gas exchange/Excretion • Diffusion – in/out of individual cells

  28. Response to Stimuli • No special nerve cells – can’t react as a whole • Individual cells can respond

  29. Reproduction of sponges • Asexual • Fragment or bud • Sexual • Hermaphrodite – egg + sperm • Some amoeboid cells become sperm, some eggs • Eggs/sperm made at different times  cross fertilize • Sperm released into water, taken in by other sponges of same species • Fertilization and early dev. In mesohyl • Embryo moves to spongocoel, leaves with water • Swims, attaches to solid object  sessile

  30. Cnidarians – Phylum Cnidaria • marine • Solitary • colonies

  31. Fig. 33-3b A jelly

  32. 3 classes of Cnidarians: • Hydrozoa • Hydras, hydroids • Polyp dominant • Scyphozoa • Jellyfish • Medusa dominant • Anthozoa • Sea anemones, corals • No medusa

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

  34. Body of Cnidarians • Radial symmetry • Hollow sac w/ mouth + surrounding tentacles at 1 end • Mouth leads to GV cavity (digestive) • Mouth – ingests food, expels waste

  35. Epidermis • Protective covering • Gastrodermis • Lines gut, digestive • Mesoglea • Gelatinous, acellular • Separates epidermis + gastrodermis

  36. 2 body shapes of Cnidarians • Polyp • Dorsal mouth w/ tentacles • Hydra • Medusa • Mouth on lower oral surface • Jellyfish

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

  38. Response in Cnidarians • Nerve nets • Nerve cells that connect sensory cells in body wall to contractile + gland cells • Cells contacted, entire body responds – crunches in

  39. Feeding in Cnidarians (hydra) • Paralyze prey with Nematocysts • Nematocysts • Stinging cells (“thread capsules”) • In cnidocytes • Stimulated – release coiled, hollow thread • Sticky OR long and coil around prey OR barbs/spines • Prey pushed into mouth • GV cavity – digestion • Body motion helps circulate contents

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

  41. Gas exchange/Excretion • Diffusion • No cell far from surface

  42. Reproduction in Cnidarians • Asexual • Budding – good conditions • Colony – buds remain on parent • Sexual • Fall or stagnant water • Become males and females • Female – ovary – single egg • Male – testis - sperm • Zygote – may become covered with shell for winter

  43. 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)

  44. Comb Jellies – Phylum Ctenophora • Marine • Luminescent • 8 rows cilia (comb) • 2 tentacles – no nematocysts – adhesive glue cells • Radial symmetry • 2 cells layers w/ mesoglea • Mouth – food in; 2 anal pores – waste out (other end)

  45. Fig. 33-3d A ctenophore, or comb jelly

  46. Flatworms – Phylum Platyhelminthes • Flat, elongated, acoelomate • Bilateral symmetry • Cephalization • “head” at anterior – moves forward; eyespots • 3 germ layers – • ectoderm, mesoderm, endoderm • Muscular pharynx • Takes in food – 1 opening mouth

  47. Flatworms cont. • Nervous system • Simple brain = 2 mass nerve tissue = ganglia – connect to 2 nerve cords • Protonephridia • Osmoregulation, waste disposal • Complex reproductive organs • No organs for circulation, gas exchange • Diffusion through body wall

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