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 Zygote Cleavage Eight-cell stage Cleavage Blastula Cross section of blastula Blastocoel Gastrulation Blastopore Gastrula Archenteron Ectoderm Endoderm Blastocoel

10. Fig. 32-8 Coelom Body covering (from ectoderm) Digestive tract (from endoderm) Tissue layer lining coelom and suspending internal organs (from mesoderm) (a) Coelomate Body covering (from ectoderm) Pseudocoelom Digestive tract (from endoderm) Muscle layer (from mesoderm) (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 vs. Deuterostomes Cleavage Protostomes –Spiral Deuterostomes –radial

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

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

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

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

17. Fig. 32-9c Anus Protostome development (examples: molluscs, annelids) Deuterostome development (examples: echinoderms, chordates) Anus Mouth Digestive tube (c) Fate of the blastopore Key Ectoderm Mesoderm Endoderm 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 Azure vase sponge (Callyspongia plicifera) Spongocoel Osculum Pore Epidermis Water flow Mesohyl Choanocyte Flagellum Collar Food particles in mucus Choanocyte Amoebocyte Phagocytosis of food particles Spicules Amoebocytes

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 (a) Colonial polyps (class Hydrozoa) (b) Jellies (class Scyphozoa) Sea wasp (class Cubozoa) (d) Sea anemone (class Anthozoa) (c)

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 Polyp Mouth/anus Body stalk Tentacle Gastrovascular cavity Gastrodermis Mesoglea Epidermis Tentacle Mouth/anus Medusa

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

40. 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

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

43. Gas exchange/Excretion Diffusion –No cell far from surface

44. 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

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

46. 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)

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

49. 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

50. 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

51. Fig. 33-3e Acoel flatworms (LM) 1.5 mm

52. Fig. 33-3f A marine flatworm

53. 3 classes of Flatworms 1. Turbellaria –Free-living –Planarians – pond Crossed eyes Auricles (“ears”) – locate food Carnivore – mouth, pharynx, GV cavity Reproduction –asexual – splits in 2 –Sexual – hermaphrodite – cross-fertilization

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

55. 2. Trematoda + Monogenea –Flukes – blood + liver –Parasites –Hooks, suckers – attach to host –Complex reproduction

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

57. 3. Cestoda –Intestinal parasite –Tapeworm – long, flat, ribbon-like –Suckers, hooks on scolex (head) –Body – proglottids (segments) Each proglottid – male and female organs (100,000 eggs) –No mouth/digestive sys. – diffusion –Lacks sense organs

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