1. INTRODUCTION TO ANIMAL DIVERSITY Chapter 32 Our Kingdom We are Animals

2. Animals Are  Species-rich  Morphologically diverse lineage of multicellular organisms on the tree of life   Distinguished by two traits   they eat   they move   The largest and most abundant predators, herbivores, and detritivores

3. Animals Are Multicellular, heterotrophic eukaryotes Heterotrophs ingest food find food by tunneling, swimming, filtering, crawling, creeping, slithering, walking, running, or flying. Dominant in both aquatic and terrestrial habitats Dominant consumers in both aquatic and terrestrial habitats Animal cells lack cell walls Animal cells lack cell walls Distinguished by two tissues Nervous tissue and muscle tissue Nervous tissue and muscle tissue Most animals reproduce sexually with the diploid stage usually dominating the life cycle

4. Methods in the Study of Animals Analyzing Comparative Morphology Analyzing Comparative Morphology The Evolution of Tissues The Evolution of Tissues Symmetry and Cephalization Symmetry and Cephalization Evolution of a Body Cavity Evolution of a Body Cavity The Protostome and Deuterostome Patterns of Development The Protostome and Deuterostome Patterns of Development The Tube-within-a-Tube Design The Tube-within-a-Tube Design A Phylogeny of Animals Based on Morphology A Phylogeny of Animals Based on Morphology Using the Fossil Record Using the Fossil Record Evaluating Molecular Phylogenies Evaluating Molecular Phylogenies

5. Themes in the Diversification of Animals Suspension (Filter) Feeding Suspension (Filter) Feeding Deposit Feeding Deposit Feeding Herbivory Herbivory Predation Predation Parasitism Parasitism Feeding Movement Feeding Movement Types of Limbs: Unjointed and Jointed Types of Limbs: Unjointed and Jointed Are All Animal Appendages Homologous? Are All Animal Appendages Homologous? Reproduction and Life Cycles Reproduction and Life Cycles

6. Key Lineages of Animals Choanoflagellates (Collar Flagellates) Porifera (Sponges) Cnidaria (Jellyfish, Corals, Anemones, Hydroids, Sea Fans) Ctenophora (Comb Jellies) Acoelomorpha

7. Monophyletic and Very Diverse The animals are a monophyletic group Animals are very diverse 34 major animal phyla are recognized 34 major animal phyla are recognized

10. Analyzing Comparative Morphology Most morphological diversity in animals is based on differences in mouths and limbs differences in mouths and limbs

14. Basic Architecture Four features define an animal's body plan 1. the number of tissue types in embryos 2. the type of body symmetry 3. the presence or absence of a fluid-filled cavity 4. the way in which the earliest events of embryo development proceed

15. The Evolution of Tissues All animals other than sponges have tissues tightly integrated structural and functional units of cells. Diploblasts embryos have two types of tissues or germ layers Ectoderm Endoderm Triploblasts embryos have three types of tissues embryos have three types of tissues Ectoderm Ectoderm Endoderm Endoderm Mesoderm Mesoderm germ layers develop into distinct adult tissues germ layers develop into distinct adult tissues

19. Symmetry and Cephalization A basic feature of a multicellular body is the presence or absence of a plane of symmetry radial symmetry radial symmetry at least two planes of symmetry. at least two planes of symmetry. bilateral symmetry bilateral symmetry a single plane of symmetry a single plane of symmetry face their environment in one direction. face their environment in one direction.

21. Cephalization Bilateral symmetry allowed Evolution of a head, or anterior region, where structures for feeding, sensing the environment, and processing information are concentrated Evolution of a head, or anterior region, where structures for feeding, sensing the environment, and processing information are concentrated

22. Evolution of a Body Cavity Animals may or may not have an internal, fluid-filled body cavity coelom coelom forms from within the mesoderm forms from within the mesoderm lined with cells from the mesoderm lined with cells from the mesoderm

24. Advantages of a Coelom Creates a medium for circulation Makes space for internal organs A hydrostatic skeleton fluid-filled chamber allows movement even without fins or limbs.

27. The Protostome and Deuterostome Patterns of Development Coelomates are bilaterally symmetric Coelomates are bilaterally symmetric except echinoderms except echinoderms three embryonic tissue layers three embryonic tissue layers Bilatera protostomes arthropods, mollusks, and segmented worms arthropods, mollusks, and segmented worms deuterostomes vertebrates and echinoderms vertebrates and echinoderms

28. Differences in Early Development Three events in early development differ in protostomes and deuterostomes Cleavage Cleavage Gastrulation Gastrulation coelom formation coelom formation

30. Cleavage Rapid series of mitotic divisions Spiral cleavage mitotic spindles of dividing cells orient at an angle to the main axis of the cells mitotic spindles of dividing cells orient at an angle to the main axis of the cells resulting in a helical arrangement resulting in a helical arrangement Radial cleavage Radial cleavage mitotic spindles of dividing cells orient parallel or perpendicular to the main axis of the cells mitotic spindles of dividing cells orient parallel or perpendicular to the main axis of the cells resulting in a pattern of cells stacked directly on top of each other resulting in a pattern of cells stacked directly on top of each other

33. The Tube-within-a-Tube Design The basic animal body plan is a tube-within-a-tube design in which the outer tube forms the body wall and the inner tube forms the gut

35. Ancestor? The animal kingdom all developed from a common ancestor ( monophyletic) probable during the Precambrian era. The animal kingdom all developed from a common ancestor ( monophyletic) probable during the Precambrian era. Probably a colonial choanoflagelate that lived about700 million years ago. Modern choanoflagellates are tiny, have a stalk and live in ponds and lakes) Probably a colonial choanoflagelate that lived about700 million years ago. Modern choanoflagellates are tiny, have a stalk and live in ponds and lakes) A hypothesis of animal origin from flagellated protists says that the colony of cells in the protist evolved into a sphere and then differenciated and especialized creating two layers of cells. A hypothesis of animal origin from flagellated protists says that the colony of cells in the protist evolved into a sphere and then differenciated and especialized creating two layers of cells.

36. The common ancestor of living animals May have lived 1.2 billion–800 million years ago May have lived 1.2 billion–800 million years ago May have resembled modern choanoflagellates, protists that are the closest living relatives of animals May have resembled modern choanoflagellates, protists that are the closest living relatives of animals Figure 32.3 Single cell Stalk

37. closest living relatives of animals a colonial, flagellated protist a colonial, flagellated protist Figure 32.4 Colonial protist, an aggregate of identical cells Hollow sphere of unspecialized cells (shown in cross section) Beginning of cell specialization Infolding Gastrula-like “protoanimal” Somatic cells Digestive cavity Reproductive cells

38. A Phylogeny of Animals Based on Morphology The phylogenetic tree indicates that a group of protists called the choanoflagellates are the closest living relatives of animals and that the Porifera (sponges) are the most ancient animal phylum.

39. Phylogeny Based on Morphology

40. Radially symmetric phyla are placed on the tree next because their tubelike body plans are relatively simple. Among the bilaterally symmetric phyla, the acoelomates and pseudocoelomates appeared first, followed by the coelomates.

41. Two major events occurred after the coelomates split into the protostomes and deuterostomes radial symmetry evolved radial symmetry evolved segmentation evolved independently in both lineages of coelomates. segmentation evolved independently in both lineages of coelomates.

42. Using the Fossil Record Most major groups of animals appear in the fossil record starting about 580 million years ago The fossil record is generally consistent with the morphological phylogeny.

45. (a) (b) Neoproterozoic Era (1 Billion–524 Million Years Ago) Early members of the animal fossil record are known as the Ediacaran fauna( first fossils of animals about 575 mya). Simple radial forms and segmented bodies with legs. Early members of the animal fossil record are known as the Ediacaran fauna( first fossils of animals about 575 mya). Simple radial forms and segmented bodies with legs. Figure 32.5a, b

47. Paleozoic Era (542–251 Million Years Ago) The Cambrian explosion marks the earliest fossil appearance of many major groups of living animals The Cambrian explosion marks the earliest fossil appearance of many major groups of living animals Is described by several current hypotheses such as predator- prey relationships, oxygen increase and evolution of the hox genes Is described by several current hypotheses such as predator- prey relationships, oxygen increase and evolution of the hox genes Figure 32.6

48. Mesozoic Era (251–65.5 Million Years Ago) During the Mesozoic era During the Mesozoic era Dinosaurs were the dominant terrestrial vertebrates Dinosaurs were the dominant terrestrial vertebrates Coral reefs emerged, becoming important marine ecological niches for other organisms Coral reefs emerged, becoming important marine ecological niches for other organisms The first mammals appeared (tiny, nocturnal insect eaters The first mammals appeared (tiny, nocturnal insect eaters

49. Cenozoic Era (65.5 Million Years Ago to the Present) The beginning of this era The beginning of this era Followed mass extinctions of both terrestrial and marine animals Followed mass extinctions of both terrestrial and marine animals Modern mammal orders and insects Modern mammal orders and insects diversified during the Cenozoic Also flowering plants appeared Also flowering plants appeared

50. Evaluating Molecular Phylogenies The phylogenetic tree based on genes for ribosomal RNA and several proteins

52. Points of Agreement All animals share a common ancestor All animals share a common ancestor Sponges are basal animals (branch from the base of tree, no tissues) Sponges are basal animals (branch from the base of tree, no tissues) Eumetazoa is a clade of animals with true tissues Eumetazoa is a clade of animals with true tissues Most animal phyla belong to the clade Bilateria Most animal phyla belong to the clade Bilateria Vertebrates belong to the clade Deuterostomia Vertebrates belong to the clade Deuterostomia

53. Disagreement over the Bilaterians The morphology-based tree The morphology-based tree Divides the bilaterians into two clades: deuterostomes and protostomes Divides the bilaterians into two clades: deuterostomes and protostomes In contrast, recent molecular studies In contrast, recent molecular studies assign two sister taxa to the protostomes rather than one: the ecdysozoans and the lophotrochozoans assign two sister taxa to the protostomes rather than one: the ecdysozoans and the lophotrochozoans

54. Important Observations Emerge From the Data 1. 1. The most ancient triploblasts lacked a coelom; 2. 2. The major event in the evolution of the Bilateria was the split between protostomes and deuterostomes 3. 3. Segmentation evolved independently in the annelids and the arthropods; and 4. 4. Pseudocoeloms arose from coeloms twice in evolutionary history

55. Phylogenetic trees are best described as 1. true and inerrant statements about evolutionary relationships. 2. hypothetical portrayals of evolutionary relationships. 3. the most accurate possible representations of genetic relationships among taxa. 4. theories of evolution. 5. the closest things to absolute certainty that modern systematists can produce.

56. Themes in the Diversification of Animals Within the phylum basic features of the body plan do not vary from species to species basic features of the body plan do not vary from species to species Diversity arose mostly because of the evolution of innovative methods for feeding and moving mostly because of the evolution of innovative methods for feeding and moving

57. Feeding The feeding tactics observed in animals can be broken into five general types: 1. suspension feeding 2. deposit feeding 3. herbivory 4. predation 5. Parasitism   Many animals undergo a metamorphosis  a change in form during development  allows juveniles and adults to exploit different sources of food

58. Suspension (Filter) Feeding Suspension feeders, or filter feeders, capture food by filtering out particles suspended in water or air This method is found in a wide variety of animal groups and has evolved many times independently

62. Deposit Feeding Deposit feeders eat their way through a substrate Food soil-dwelling bacteria, protists, fungi, and archaea soil-dwelling bacteria, protists, fungi, and archaea —the dead and partially decomposed remains of organisms detritus—the dead and partially decomposed remains of organisms Depending on food herbivores (plant eaters), parasites, detritivores (detritus eaters), or predators herbivores (plant eaters), parasites, detritivores (detritus eaters), or predators

64. Herbivory Herbivores animals that digest algae or plant tissues animals that digest algae or plant tissues complex mouths with structures that make biting and chewing or sucking possible complex mouths with structures that make biting and chewing or sucking possible

69. Predation Sit-and-wait predators rarely move at all until prey is captured stalkers pursue their prey

72. Parasitism Parasites are much smaller than their victims and often harvest nutrients without causing death Endoparasites live inside their hosts live inside their hosts often wormlike in shape often wormlike in shape can be extremely simple morphologically can be extremely simple morphologically Ectoparasites live outside their hosts live outside their hosts usually have grasping mouthparts usually have grasping mouthparts pierce the host’s exterior and suck the nutrient-rich fluids inside pierce the host’s exterior and suck the nutrient-rich fluids inside

75. Movement Many animals are sit-and-wait predators, and some are sessile throughout their adult lives. But the vast majority of animals move under their own power either as juveniles or as adults.

76. Function of Movement three functions in adult animals: 1. Finding food 2. finding mates 3. escaping from predators.

77. Limbs A major innovation in animals made highly controlled, rapid movement possible made highly controlled, rapid movement possible Two types Unjointed Unjointed saclike Jointed move when muscles that are attached to a skeleton contract or relax

82. Homologous vs Non-Homologous Biologists have argued that at least a few of the same genes are involved in the development of all appendages observed in animals Hypothesis is that all animal appendages have some degree of genetic homology that they are all derived from appendages that were present in a common ancestor. This hypothesis is controversial, however, and research continues

84. Reproduction and Life Cycles At least some species in most animal phyla can reproduce asexually (via mitosis), as well as sexually (via meiosis). Sexual reproduction can occur with internal or external fertilization

87. Development Eggs or embryos may be retained in the female’s body during development viviparous May be laid outside the body oviparous Female retains eggs inside her body during early development embryos are nourished by yolk inside the egg and not by nutrients transferred directly from the mother embryos are nourished by yolk inside the egg and not by nutrients transferred directly from the mother ovoviviparous Vast majority of animals are oviparous

90. Development After a sperm fertilizes an egg After a sperm fertilizes an egg The zygote undergoes cleavage, leading to the formation of a blastula The zygote undergoes cleavage, leading to the formation of a blastula The blastula undergoes gastrulation The blastula undergoes gastrulation Resulting in the formation of embryonic tissue layers and a gastrula Resulting in the formation of embryonic tissue layers and a gastrula

91. Zygote Cleavage Eight-cell stage Cleavage Blastula Cross section of blastula Blastocoel Gastrula Gastrulation Endoderm Ectoderm Blastopore. Early embryonic development in animals Early embryonic development in animals Figure 32.2 In most animals, cleavage results in the formation of a multicellular stage called a blastula. The blastula of many animals is a hollow ball of cells. 3 The endoderm of the archenteron de- velops into the tissue lining the animal’s digestive tract. 6 The blind pouch formed by gastru- lation, called the archenteron, opens to the outside via the blastopore. 5 Most animals also undergo gastrulation, a rearrangement of the embryo in which one end of the embryo folds inward, expands, and eventually fills the blastocoel, producing layers of embryonic tissues: the ectoderm (outer layer) and the endoderm (inner layer). 4 Only one cleavage stage–the eight-cell embryo–is shown here. 2 The zygote of an animal undergoes a succession of mitotic cell divisions called cleavage. 1

92. Metamorphosis The change from juvenile to adult body type Larva juvenile individual juvenile individual looks substantially different from the adult looks substantially different from the adult Nymph juvenile individual juvenile individual looks like a miniature adult looks like a miniature adult

94. Pupation When a larva has grown sufficiently, it secretes a protective case and is now known as a pupa

96. Into an Adult During pupation, the pupa’s body is completely remodeled into a new, adult form

98. Holometabolous Complete metamorphosis two-step process two-step process from larva to pupa to adult from larva to pupa to adult involving dramatic changes in morphology and habitat use involving dramatic changes in morphology and habitat use

100. Hemimetabolou Incomplete metamorphosis One-step process of sexual maturation. Limited morphological difference between juvenile and adult

102. Marine Animals Complete metamorphosis extremely common in marine animals most cnidarians have two distinct body types during their life cycle a largely sessile form called a a largely sessile form called a polyp alternates with a free-floating stage called a alternates with a free-floating stage called a medusa