biology bo101

1. 1 Biology BO101/BO106/BO111 An Introduction to Animal Diversity Dr. Colin Lawton

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3. 3 Animal Characteristics Plants � autotrophs (generate organic material through photosynthesis); cells have cell walls Fungi � heterotrophs (feed by absorption); cells have cell walls ANIMALS multicellular, heterotrophic eukaryotes ingest food, digest internally cells lack cell walls specialized cells (nerves and muscles)

4. 4 Animal Kingdom 1.3 million living (extant) species of animals have been identified 99% of all animal species are extinct The common ancestor of living animals may have lived between 675 and 875 million years ago This ancestor may have resembled modern choanoflagellates, protists that are the closest living relatives of animals

5. 5 Figure 32.3 Three lines of evidence that choanoflagellates are closely related to animalsFigure 32.3 Three lines of evidence that choanoflagellates are closely related to animals

6. 6 Body Plans Zoologists sometimes categorize animals according to a body plan, a set of morphological and developmental traits Animals can be categorized according to the symmetry of their bodies, or lack of it Some animals have radial symmetry Others have bilateral symmetry Some animals lack symmetry

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8. 8 Symmetry Radially symmetrical animals have A dorsal (top) side and a ventral (bottom) side Bilaterally symmetrical animals have: A dorsal (top) side and a ventral (bottom) side A right and left side Anterior (head) and posterior (tail) ends Cephalization, the development of a head

9. 9 Tissues Animal body plans also vary according to the organization of the animal�s tissues Tissues are collections of specialized cells isolated from other tissues by membranous layers During development, three germ layers give rise to the tissues and organs of the animal embryo

10. 10 Germ Layers Ectoderm is the germ layer covering the embryo�s surface Endoderm is the innermost germ layer and lines the developing digestive tube Diploblastic animals have ectoderm and endoderm Triploblastic animals also have an intervening mesoderm layer; these include all bilaterians

11. 11 Diploblastic

12. 12 Body Cavity Most triploblastic animals possess a body cavity A true body cavity is called a coelom and is derived from mesoderm Coelomates are animals that possess a true coelom

13. 13 Triploblastic Acoelomate

14. 14 Triploblastic Coelomate

15. 15 Early Development

16. 16 Development Based on early development, many animals can be categorized as having protostome development or deuterostome development

17. 17 Cleavage In protostome development, cleavage is spiral and determinate In deuterostome development, cleavage is radial and indeterminate Indeterminate cleavage makes possible identical twins, and embryonic stem cells

18. 18 Coelom Formation

19. 19 Fate of the Blastopore

20. 20 You should be able to: List the characteristics that combine to define animals Understand and differentiate between the following terms: radial and bilateral symmetry diploblastic and triploblastic acoelomate, pseudocoelomate, and coelomate zygote, blastula, gastrula spiral/determinate and radial/indeterminate cleavage Compare the developmental differences between protostomes and deuterostomes

21. 21 Biology BO101/BO111 Invertebrate animals Dr. Colin Lawton

22. 22 Invertebrate Animals Invertebrates are animals that lack a backbone They account for 95% of known animal species Divided into about 35 Phyla Occupy every possible habitat, showing immense diversity

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24. 24 Phyla Calcarea and Silicea - Sponges Sponges lack true tissues and organs Sponges are sedentary suspension feeders They live in both fresh and marine waters 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

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26. 26 Sponges Sponges consist of a noncellular mesohyl layer between two cell layers Amoebocytes are found in the mesohyl and play roles in digestion and structure Most sponges are hermaphrodites: Each individual functions as both male and female

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28. 28 Phylum Cnidaria All animals except sponges belong to the clade Eumetazoa, animals with true tissues Phylum Cnidaria is one of the oldest groups 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

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30. 30 Cnidarian 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 Cnidarians are carnivores that use tentacles armed with cnidocytes to capture prey

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33. 33 Phylum Platyhelminthes Flatworms 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

34. 34 Flatworms include free living form (e.g. Planarians)� and parasitic forms such as flukes and tapeworms

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37. 37 Phylum Mollusca Phylum Mollusca includes snails and slugs, oysters and clams, and octopuses and squids Most molluscs are marine, though some inhabit fresh water and some are terrestrial Molluscs are soft-bodied animals, but most are protected by a hard shell All molluscs have a similar body plan with three main parts: Muscular foot, Visceral mass, Mantle

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39. 39 Molluscs There are 4 major classes � are gastropods The most distinctive characteristic of gastropods is torsion, which causes the animal�s anus and mantle to end up above its head

40. 40 Bivalves Molluscs of class Bivalvia include many species of clams, oysters, mussels, and scallops They have a shell divided into two halves

41. 41 Cephalopods Class Cephalopoda includes squids and octopuses, carnivores with beak-like jaws surrounded by tentacles of their modified foot Most octopuses creep along the sea floor in search of prey

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43. 43 Phylum Annelida Annelids have bodies composed of a series of fused rings They include earthworms, polychaetes and leeches

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46. 46 Phylum Arthropoda 75% of all known animals are arthropods The arthropod body plan consists of a segmented body, hard exoskeleton, and jointed appendages Their appendages have evolved for many different functions The body of an arthropod is completely covered by an exoskeleton known as the cuticle When an arthropod grows, it molts its exoskeleton

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48. 48 Arthropods Arthropods have an open circulatory system in which fluid called hemolymph is circulated into the spaces surrounding the tissues and organs A variety of organs specialized for gas exchange have evolved in arthropods There are four main lineages: Cheliceriforms (scorpions, ticks, mites, and spiders) Myriapods (centipedes and millipedes) Hexapods (insects and relatives) Crustaceans (crabs, lobsters, shrimps, barnacles, and many others)

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51. 51 Subphylum Hexapoda There are more insect species than all other forms of life combined They live in almost every terrestrial habitat and in fresh water The internal anatomy of an insect includes several complex organ systems Flight is one key to the great success of insects An animal that can fly can escape predators, find food, and disperse to new habitats very quickly

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55. 55 Biology BO101/BO106/BO111 Deuterostomes Dr. Colin Lawton

56. 56 Animal Kingdom Tuesday�s lectures: Animal characteristics Animal diversity � body plans Radial and bilateral symmetry Diploblastic and triploblastic Acoelomate and coelomate Developmental differences Invertebrate groups�

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59. 59 Phylum Echinodermata Sea stars and most other echinoderms are slow-moving or sessile marine animals A thin epidermis covers an endoskeleton of hard calcareous plates Echinoderms have a unique water vascular system; a network of hydraulic canals branching into tube feet that function in locomotion, feeding, and gas exchange Males and females are usually separate

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62. 62 Phylum Chordata Phylum Chordata consists of two subphyla of invertebrates as well as hagfishes and all vertebrates Chordates share many features of embryonic development with echinoderms The animals called vertebrates get their name from vertebrae, the bones that make up the backbone There are about 52,000 species of vertebrates Vertebrates have great disparity, a wide range of differences within the group

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64. 64 Chordate characteristics Four key characters of chordates: Notochord; Dorsal, hollow nerve cord; Pharyngeal slits or clefts; Muscular, post-anal tail

65. 65 Notochord The notochord is a longitudinal, flexible rod between the digestive tube and nerve cord It provides skeletal support throughout most of the length of a chordate In most vertebrates, a more complex, jointed skeleton develops, and the adult retains only remnants of the embryonic notochord

66. 66 Nerve cord and pharyngeal gill slits The nerve cord of a chordate embryo develops from a plate of ectoderm that rolls into a tube dorsal to the notochord The nerve cord develops into the central nervous system: the brain and the spinal cord Functions of pharyngeal slits: Suspension-feeding structures in many invertebrate chordates Gas exchange in vertebrates (except vertebrates with limbs) Develop into parts of the ear, head, and neck in tetrapods

67. 67 Muscular, Post-anal tail Chordates have a tail posterior to the anus In many species, the tail is greatly reduced during embryonic development The tail contains skeletal elements and muscles It provides propelling force in many aquatic species

68. 68 Lancelets Marine suspension feeders that retain the chordate body plan as adults

69. 69 Tunicates They are marine suspension feeders commonly called sea squirts As an adult, a tunicate draws in water through an incurrent siphon, filtering food particles Tunicates most resemble chordates during their larval stage, which may last only a few minutes

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71. 71 Craniates and Vertebrates Craniates are chordates with distinct heads Hagfishes have a cartilaginous skull and axial rod of cartilage derived from the notochord, but lack jaws and vertebrae Lampreys are jawless vertebrates inhabiting various marine and freshwater habitats They have cartilaginous segments surrounding the notochord and arching partly over the nerve cord

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73. 73 Evolution of the jaw Today, jawed vertebrates, or gnathostomes, outnumber jawless vertebrates The jaws evolved from the pharyngeal slits

74. 74 Chondrichthyans Chondrichthyans (Chondrichthyes) have a skeleton composed primarily of cartilage The largest and most diverse group of chondrichthyans includes the sharks, rays, and skates

75. 75 Fishes Fish can be divided into ray-finned fish and lobe-finned fish Most of the familiar fish belong to ray-finned fish Coelacanths and lungfish have lobe-fins, which have muscular pelvic and pectoral fins

76. 76 Limbs One of the most significant events in vertebrate history was when the fins of some lobe-fins evolved into the limbs and feet of tetrapods

77. 77 Amphibians Amphibians are represented by about 6,150 species of organisms in three orders They include salamanders, frogs and a legless form called the caecilians

78. 78 Amniotes Amniotes are tetrapods that have a terrestrially adapted egg. Their living members are the reptiles, including birds, and mammals

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