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  • Figure 33.3 Exploring: Invertebrate Diversity
  • Figure 33.3 Exploring: Invertebrate Diversity
  • Figure 33.3 Exploring: Invertebrate Diversity
  • Figure 33.3 Exploring: Invertebrate Diversity
  • Figure 33.UN01 In-text figure, p. 670
  • Figure 33.4 Anatomy of a sponge.
  • Figure 33.4 Anatomy of a sponge.
  • Figure 33.4 Anatomy of a sponge.
  • Figure 33.4 Anatomy of a sponge.
  • Figure 33.UN02 In-text figure, p. 671
  • Figure 33.5 Polyp and medusa forms of cnidarians.
  • Figure 33.6 A cnidocyte of a hydra.
  • Figure 33.7 Cnidarians.
  • Figure 33.8 The life cycle of the hydrozoan Obelia .
  • Figure 33.8 The life cycle of the hydrozoan Obelia .
  • Figure 33.8 The life cycle of the hydrozoan Obelia .
  • Figure 33.UN03 In-text figure, p. 674
  • Figure 33.9 A free-living marine flatworm.
  • Figure 33.10 Anatomy of a planarian.
  • Figure 33.11 The life cycle of a blood fluke ( Schistosoma mansoni ), a trematode.
  • Figure 33.12 Anatomy of a tapeworm.
  • Figure 33.13 A rotifer.
  • Figure 33.14 Lophophorates.
  • Figure 33.15 The basic body plan of a mollusc.
  • Figure 33.16 A chiton.
  • Figure 33.17 Gastropods.
  • Figure 33.17 Gastropods.
  • Figure 33.17 Gastropods.
  • Figure 33.18 The results of torsion in a gastropod.
  • Figure 33.19 A bivalve.
  • Figure 33.20 Anatomy of a clam.
  • Figure 33.21 Cephalopods.
  • Figure 33.22 Impact: Molluscs: The Silent Extinction
  • Figure 33.22 Impact: Molluscs: The Silent Extinction
  • Figure 33.22 Impact: Molluscs: The Silent Extinction
  • Figure 33.23 A polychaete.
  • Figure 33.24 Anatomy of an earthworm, an oligochaete.
  • Figure 33.24 Anatomy of an earthworm, an oligochaete.
  • Figure 33.25 A leech.
  • Figure 33.UN04 In-text figure, p. 683
  • Figure 33.26 A free-living nematode (colorized SEM).
  • Figure 33.27 Juveniles of the parasitic nematode Trichinella spiralis encysted in human muscle tissue (LM).
  • Figure 33.28 A trilobite fossil.
  • Figure 33.29 Inquiry: Did the arthropod body plan result from new Hox genes?
  • Figure 33.30 External anatomy of an arthropod.
  • Figure 33.31 Horseshoe crabs ( Limulus polyphemus ).
  • Figure 33.32 Arachnids.
  • Figure 33.33 Anatomy of a spider.
  • Figure 33.34 Myriapods.
  • Figure 33.35 Anatomy of a grasshopper, an insect.
  • Figure 33.36 Ladybird beetle in flight.
  • Figure 33.37 Complete metamorphosis of a butterfly.
  • Figure 33.38 Exploring: Insect Diversity
  • Figure 33.39 Crustaceans.
  • Figure 33.39 Crustaceans.
  • Figure 33.39 Crustaceans.
  • Figure 33.UN05 In-text figure, p. 692
  • Figure 33.40 Anatomy of a sea star, an echinoderm.
  • Figure 33.41 A sea daisy (clade Asteroidea).
  • Figure 33.42 A brittle star (clade Ophiuroidea).
  • Figure 33.43 A sea urchin (clade Echinoidea).
  • Figure 33.44 A feather star (clade Crinoidea).
  • Figure 33.45 A sea cucumber (clade Holothuroidea).
  • Figure 33.UN06 Summary figure, all Concepts
  • Figure 33.UN06a Summary figure, all Concepts (top)
  • Figure 33.UN06b Summary figure, all Concepts (bottom)
  • Figure 33.UN09 Test Your Understanding, question 8
  • Figure 33.UN10 Appendix A: answer for Test Your Understanding, question 7
  • 33 lecture presentation

    1. 1. Chapter 33 Invertebrates
    2. 2. Review:
    3. 3. Gastrulation
    4. 4. Symmetry
    5. 5. Overview: Life Without a Backbone • Invertebrates are animals that lack a backbone • They account for 95% of known animal species • They are morphologically diverse – For example, the Christmas tree worm (Spirobranchus giganteus) has tentacles for gas exchange and feeding
    6. 6. Figure 33.3a Porifera (5,500 species) Placozoa (1 species) 0.5 mm A sponge Cnidaria (10,000 species) A placozoan (LM) Ctenophora (100 species) A jelly Acoela (400 species) 1.5 mm Acoel flatworms (LM) A ctenophore, or comb jelly
    7. 7. Figure 33.3bi An octopus
    8. 8. Figure 33.3c Loricifera (10 species) Priapula (16 species) Onychophora (110 species) 50 µm A loriciferan (LM) A priapulan An onychophoran Nematoda Tardigrada Arthropoda (25,000 species) (800 species) (1,000,000 species) 100 µm A roundworm (colored SEM) Tardigrades A scorpion (an arachnid) Ecdysozoa (colorized SEM)
    9. 9. Figure 33.3d Hemichordata Chordata (85 species) (52,000 species) A tunicate Echinodermata (7,000 species) An acorn worm Deuterostomia A sea urchin
    10. 10. Sponges are basal animals that lack truetissues • Animals in the phylum Porifera are known informally as sponges • They are sedentary and live in marine waters or fresh water
    11. 11. Figure 33.UN01 Porifera Cnidaria Lophotrochozoa Ecdysozoa Deuterostomia
    12. 12. • Sponges are suspension feeders, capturing food particles suspended in the water that passes through their body• Water is drawn through pores into a cavity called the spongocoel and out through an opening called the osculum• Sponges lack true tissues and organs
    13. 13. Figure 33.4 Food particles in mucus Flagellum Choanocyte Azure vase sponge Choanocyte Collar (Callyspongia plicifera) Osculum Spongocoel Phagocytosis of food particles Amoebocyte Pore Spicules Epidermis Water flow Amoebocytes Mesohyl
    14. 14. Figure 33.4a Azure vase sponge (Callyspongia plicifera)
    15. 15. Figure 33.4b Choanocyte Osculum Spongocoel Pore Spicules Epidermis Water flow Amoebocytes Mesohyl
    16. 16. Figure 33.4c Food particles in mucus Flagellum Choanocyte Collar Phagocytosis of food particles Amoebocyte
    17. 17. • Choanocytes, flagellated collar cells, generate a water current through the sponge and ingest suspended food• Sponges consist of a gelatinous 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
    18. 18. Cnidarians are an ancient phylum ofeumetazoans • All animals except sponges and a few other groups belong to the clade Eumetazoa, animals with true tissues • Phylum Cnidaria is one of the oldest groups in this clade
    19. 19. Figure 33.UN02 Porifera Eumetazoa Cnidaria Lophotrochozoa Ecdysozoa Deuterostomia
    20. 20. • 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
    21. 21. • There are two variations on the body plan: the sessile polyp and motile medusa• A polyp adheres to the substrate by the aboral end of its body• A medusa has a bell-shaped body with its mouth on the underside• Medusae do not attach to the substate but move freely
    22. 22. Figure 33.5 Mouth/anus Tentacle Gastrovascular cavity Gastrodermis Mesoglea Body stalk Epidermis Tentacle Mouth/anus Polyp Medusa
    23. 23. • 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
    24. 24. Figure 33.6 Tentacle Cuticle of prey Thread Nematocyst “Trigger” Thread discharges Thread (coiled) Cnidocyte
    25. 25. • Phylum Cnidaria is divided into four major classes – Hydrozoa – Scyphozoa – Cubozoa – Anthozoa
    26. 26. Figure 33.7 (b) Scyphozoa (c) Cubozoa (d) Anthozoa (a) Hydrozoa
    27. 27. Hydrozoans • Most hydrozoans alternate between polyp and medusa forms • Hydra, a freshwater cnidarian, exists only in polyp form and reproduces asexually by budding
    28. 28. Figure 33.8-1 Reproductive Feeding polyp polyp Medusa bud Gonad Medusa Portion of a colony of polyps Key 1 mm Haploid (n) Diploid (2n)
    29. 29. Figure 33.8-2 Reproductive Feeding polyp polyp Medusa MEIOSIS bud Gonad Medusa Egg Sperm SEXUAL REPRODUCTION Portion of a colony FERTILIZATION of polyps Zygote Key 1 mm Haploid (n) Diploid (2n)
    30. 30. Figure 33.8-3 Reproductive Feeding polyp polyp Medusa MEIOSIS bud Gonad Medusa Egg Sperm SEXUAL ASEXUAL REPRODUCTION Portion REPRODUCTION of a (BUDDING) colony FERTILIZATION of polyps Zygote Developing Planula polyp (larva) Mature polyp Key 1 mm Haploid (n) Diploid (2n)
    31. 31. Scyphozoans • In the class Scyphozoa, jellies (medusae) are the prevalent form of the life cycle
    32. 32. Cubozoans • In the class Cubozoa, which includes box jellies and sea wasps, the medusa is box-shaped and has complex eyes • Cubozoans often have highly toxic cnidocytes
    33. 33. Anthozoans • Class Anthozoa includes the corals and sea anemones, and these cnidarians occur only as polyps • Corals often form symbioses with algae and secrete a hard external skeleton
    34. 34. Lophotrochozoans, a clade identified bymolecular data, have the widest range ofanimal body forms • Bilaterian animals have bilateral symmetry and triploblastic development • Most have a coelom and a digestive tract with two openings • The clade Bilateria contains Lophotrochozoa, Ecdysozoa, and Deuterostomia
    35. 35. Figure 33.UN03 Porifera Cnidaria Lophotrochozoa Bilateria Ecdysozoa Deuterostomia
    36. 36. • The clade Lophotrochozoa was identified by molecular data• Some develop a lophophore for feeding, others pass through a trochophore larval stage, and a few have neither feature• Lophotrochozoa includes the flatworms, rotifers, ectoprocts, brachiopods, molluscs, and annelids
    37. 37. 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 with one opening • Gas exchange takes place across the surface, and protonephridia regulate the osmotic balance
    38. 38. • Flatworms are divided into two lineages – Catenulida, or “chain worms,” reproduce asexually by budding – Rhabditophora are more diverse and include both free-living and parasitic species
    39. 39. Figure 33.9 5 mm
    40. 40. Free-Living Species • The best-known rhabditophorans are planarians • Planarians live in fresh water and prey on smaller animals • Planarians have light-sensitive eyespots and centralized nerve nets
    41. 41. • 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
    42. 42. Figure 33.10 Gastrovascular cavity Pharynx Gastrovascular cavity Mouth Eyespots Ventral nerve cords Ganglia
    43. 43. Parasitic Species • Parasitic rhabditophorans live in or on other animals • Two important groups of parasitic rhabditophorans are the trematodes and the tapeworms
    44. 44. Trematodes• Trematodes 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• They produce surface proteins that mimic their host and release molecules that manipulate the host’s immune system
    45. 45. Figure 33.11 Male Human host Female 1 mm Mature flukes Motile Ciliated larva larva Snail host
    46. 46. Tapeworms• Tapeworms are parasites of vertebrates and lack a digestive system• Tapeworms absorb nutrients from the host’s intestine
    47. 47. • The scolex contains suckers and hooks for attaching to the host• Proglottids are units that contain sex organs and form a ribbon behind the scolex• Fertilized eggs, produced by sexual reproduction, leave the host’s body in feces
    48. 48. Figure 33.12 100 µm Hooks Sucker Proglottids with reproductive structures Scolex
    49. 49. Rotifers • Rotifers, phylum Rotifera, are tiny animals that inhabit fresh water, the ocean, and damp soil • Rotifers are smaller than many protists but are truly multicellular and have specialized organ systems
    50. 50. Figure 33.13 Jaws Crown of cilia Anus Stomach 0.1 mm
    51. 51. • Rotifers have an alimentary canal, a digestive tube with a separate mouth and anus that lies within a fluid-filled pseudocoelom• Rotifers reproduce by parthenogenesis, in which females produce offspring from unfertilized eggs• Some species are unusual in that they lack males entirely
    52. 52. Lophophorates: Ectoprocts and Brachiopods • Lophophorates have a lophophore, a crown of ciliated tentacles around their mouth • Lophophorates have a true coelom • Lophophorates include two phyla: Ectoprocta and Brachiopoda
    53. 53. • Ectoprocts (also called bryozoans) are sessile colonial animals that superficially resemble plants• A hard exoskeleton encases the colony, and some species are reef builders
    54. 54. Figure 33.14 Lophophore Lophophore (b) Lampshell, a brachiopod (a) Ectoprocts, colonial lophophorates
    55. 55. • 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• Brachiopods are marine and attach to the seafloor by a stalk
    56. 56. Molluscs • Phylum Mollusca includes snails and slugs, oysters and clams, and octopuses and squids • Most molluscs are marine, though some inhabit fresh water and some snails and slugs are terrestrial • Molluscs are soft-bodied animals, but most are protected by a hard shell
    57. 57. • All molluscs have a similar body plan with three main parts – Muscular foot – Visceral mass – Mantle• Many molluscs also have a water-filled mantle cavity and feed using a rasplike radula
    58. 58. Figure 33.15 Nephridium Heart Visceral mass Digestive tract Coelom Intestine Gonads Mantle Mantle Stomach cavity Shell Mouth Radula Anus Gill Mouth Radula Foot Nerve Esophagus cords
    59. 59. • Most molluscs have separate sexes with gonads located in the visceral mass, but many snails are hermaphrodites• The life cycle of many molluscs includes a ciliated larval stage called a trochophore
    60. 60. • Four of the major classes of molluscs are – Polyplacophora (chitons) – Gastropoda (snails and slugs) – Bivalvia (clams, oysters, and other bivalves) – Cephalopoda (squids, octopuses, cuttlefish, and chambered nautiluses)
    61. 61. Chitons • Chitons are oval-shaped marine animals encased in an armor of eight dorsal plates • They use their foot like a suction cup to grip rock, and their radula to scrape algae off the rock surface
    62. 62. Figure 33.16
    63. 63. Gastropods • About three-quarters of all living species of molluscs are gastropods
    64. 64. Figure 33.17 (a) A land snail (b) A sea slug (nudibranch)
    65. 65. Figure 33.17a (a) A land snail
    66. 66. Figure 33.17b (b) A sea slug (nudibranch)
    67. 67. • Most gastropods are marine, but many are freshwater and terrestrial species• The most distinctive characteristic of gastropods is torsion, which causes the animal’s anus and mantle to end up above its head; torsion is different from the coiling of a shell• Most have a single, spiraled shell• Slugs lack a shell or have a reduced shell
    68. 68. Figure 33.18 Mantle Stomach Intestine cavity Anus Mouth
    69. 69. Bivalves • Bivalves are marine and include many species of clams, oysters, mussels, and scallops • They have a shell divided into two halves drawn together by adductor muscles • Some bivalves have eyes and sensory tentacles along the edge of their mantle
    70. 70. Figure 33.19
    71. 71. • The mantle cavity of a bivalve contains gills that are used for feeding as well as gas exchange
    72. 72. Figure 33.20 Coelom Hinge area Mantle Gut Heart Adductor muscle (one or two) Digestive gland Anus Mouth Excurrent siphon Shell Palp Water flow Foot Mantle Incurrent cavity Gonad Gill siphon
    73. 73. Cephalopods • Cephalopods are carnivores with beak-like jaws surrounded by tentacles of their modified foot • Most octopuses creep along the sea floor in search of prey
    74. 74. Figure 33.21 Squid Octopus Chambered nautilus
    75. 75. • Squids use their siphon to fire a jet of water, which allows them to swim very quickly
    76. 76. • One small group of shelled cephalopods, the nautiluses, survives today
    77. 77. • Cephalopods have a closed circulatory system, well-developed sense organs, and a complex brain• Shelled cephalopods called ammonites were common but went extinct at the end of the Cretaceous 65.5 million years ago
    78. 78. Protecting Freshwater and TerrestrialMolluscs • Molluscs are the animal group with the largest number of recent extinctions • The most threatened groups are – Freshwater bivalves, including pearl mussels – Terrestrial gastropods, including Pacific island land snails • These molluscs are threatened by habitat loss, pollution, and non-native species
    79. 79. Figure 33.22 Molluscs Other invertebrates Amphibians Insects Birds Fishes Mammals Reptiles (excluding An endangered Pacific Recorded extinctions of animal birds) island land snail, species (Data: International Union for Partula suturalis Conservation of Nature, 2008) Workers on a mound of pearl mussels killed to make buttons (ca. 1919)
    80. 80. Figure 33.22b Molluscs Other invertebrates Amphibians Insects Birds Fishes Mammals Reptiles (excluding Recorded extinctions of animal birds) species (Data: International Union for Conservation of Nature, 2008)
    81. 81. Figure 33.22c Workers on a mound of pearl mussels killed to make buttons (ca. 1919)
    82. 82. Annelids • Annelids have bodies composed of a series of fused rings • Annelids are coelomates • The phylum Annelida is divided into two groups – Polychaeta (polychaetes) – Oligochaeta (earthworms and their relatives, and leeches)
    83. 83. Polychaetes • Members of class Polychaetes have paddle-like parapodia that work as gills and aid in locomotion • Most polychaetes are marine
    84. 84. Figure 33.23 Parapodia
    85. 85. Oligochaetes • Oligochaetes (class Oligochaeta) are named for relatively sparse chaetae, bristles made of chitin
    86. 86. Earthworms• Earthworms eat through soil, extracting nutrients as the soil moves through the alimentary canal• Earthworms are hermaphrodites but cross-fertilize• Some reproduce asexually by fragmentation
    87. 87. Figure 33.24 Cuticle Coelom Epidermis Septum (partition Circular muscle between segments) Metanephridium Longitudinal muscle Anus Dorsal vessel Chaetae Intestine Skin Fused Ventral vessel nerve cords Nephrostome Metanephridium Clitellum Esophagus Crop Pharynx Intestine Giant Australian earthworm Cerebral Gizzard ganglia Ventral nerve cords Mouth Subpharyngeal Circulatory with segmental ganglia ganglion system vessels
    88. 88. Figure 33.24a Giant Australian earthworm
    89. 89. Leeches• Most species of leeches live in fresh water; some are marine or terrestrial• Leeches include predators of invertebrates, and parasites that suck blood• Leeches secrete a chemical called hirudin to prevent blood from coagulating
    90. 90. Figure 33.25
    91. 91. Ecdysozoans are the most species-richanimal group • Ecdysozoans are covered by a tough coat called a cuticle • The cuticle is shed or molted through a process called ecdysis • The two largest phyla are nematodes and arthropods
    92. 92. Figure 33.UN04 Porifera Cnidaria Lophotrochozoa Ecdysozoa Deuterostomia
    93. 93. Nematodes • Nematodes, or roundworms, are found in most aquatic habitats, in the soil, in moist tissues of plants, and in body fluids and tissues of animals • They have an alimentary canal, but lack a circulatory system • Reproduction in nematodes is usually sexual, by internal fertilization
    94. 94. Figure 33.26 25 µm
    95. 95. • Caenorhabditis elegans is a model organism in research• Some species of nematodes are important parasites of plants and animals• Thrichinella spiralis can be acquired by humans from undercooked pork
    96. 96. Figure 33.27 Encysted juveniles Muscle tissue 50 µm
    97. 97. Arthropods • Two out of every three known species of animals are arthropods • Members of the phylum Arthropoda are found in nearly all habitats of the biosphere
    98. 98. Arthropod Origins • The arthropod body plan consists of a segmented body, hard exoskeleton, and jointed appendages • This body plan dates to the Cambrian explosion (535–525 million years ago) • Early arthropods show little variation from segment to segment
    99. 99. Figure 33.28
    100. 100. • Arthropod evolution is characterized by a decrease in the number of segments and an increase in appendage specialization• These changes may have been caused by changes in Hox gene sequence or regulation
    101. 101. Figure 33.29 EXPERIMENT Other ecdysozoans Origin of Ubx and abd-A Hox genes? Arthropods Common ancestor Onychophorans RESULTS Ant = antenna J = jaws L1–L15 = body segments
    102. 102. General Characteristics of Arthropods • The appendages of some living arthropods are modified for functions such as walking, feeding, sensory reception, reproduction, and defense
    103. 103. Figure 33.30 Cephalothorax Abdomen Antennae Thorax Head (sensory reception) Swimming appen- dages (one pair per abdominal segment Walking legs Pincer Mouthparts (defense) (feeding)
    104. 104. • The body of an arthropod is completely covered by the cuticle, an exoskeleton made of layers of protein and the polysaccharide chitin• When an arthropod grows, it molts its exoskeleton
    105. 105. • Arthropods have eyes, olfactory receptors, and antennae that function in touch and smell• Arthropods have an open circulatory system in which hemolymph is circulated into the spaces surrounding the tissues and organs• A variety of organs specialized for gas exchange have evolved in arthropods
    106. 106. • Molecular evidence suggests that living arthropods consist of four major lineages that diverged early in the phylum’s evolution – Chelicerates (sea spiders, horseshoe crabs, scorpions, ticks, mites, and spiders) – Myriapods (centipedes and millipedes) – Hexapods (insects and relatives) – Crustaceans (crabs, lobsters, shrimps, barnacles, and many others)
    107. 107. Chelicerates • Chelicerates, subphylum Chelicerata, are named for clawlike feeding appendages called chelicerae • The earliest cheliceriforms were eurypterids (water scorpions) • Most marine cheliceriforms (including eurypterids) are extinct, but some species survive today, including horseshoe crabs
    108. 108. Figure 33.31
    109. 109. • Most modern cheliceriforms are arachnids, which include spiders, scorpions, ticks, and mites
    110. 110. Figure 33.32 50 µm Scorpion Dust mite Web-building spider
    111. 111. • Arachnids have an abdomen and a cephalothorax, which has six pairs of appendages: the chelicerae, the pedipalps, and four pairs of walking legs• Gas exchange in spiders occurs in respiratory organs called book lungs• Many spiders produce silk, a liquid protein, from specialized abdominal glands
    112. 112. Figure 33.33 Intestine Stomach Heart Brain Digestive gland Eyes Ovary Poison gland Anus Book lung Spinnerets Gonopore Chelicera Pedipalp (exit for eggs) Sperm Silk gland receptacle
    113. 113. Myriapods • Subphylum Myriapoda includes millipedes and centipedes • Myriapods are terrestrial, and have jaw-like mandibles • Millipedes eat decaying leaves and plant matter • Millipedes have many legs, with two pairs per trunk segment
    114. 114. Figure 33.34 (a) Millipede (b) Centipede
    115. 115. • Centipedes are carnivores• Centipedes have one pair of legs per trunk segment
    116. 116. Insects • Subphylum Hexapoda, insects and relatives, has more 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
    117. 117. Figure 33.35 Abdomen Thorax Head Compound eye Antennae Heart Dorsal artery Crop Cerebral Anus ganglion Vagina Malpighian tubules Ovary Tracheal tubes Nerve cords Mouthparts
    118. 118. • Insects diversified several times following the evolution of flight, adaptation to feeding on gymnosperms, and the expansion of angiosperms• Insect and plant diversity declined during the Cretaceous extinction, but has been increasing in the 65 million years since
    119. 119. • 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 much faster than organisms that can only crawl
    120. 120. Figure 33.36
    121. 121. • Many insects undergo metamorphosis during their development• In incomplete metamorphosis, the young, called nymphs, resemble adults but are smaller and go through a series of molts until they reach full size
    122. 122. • Insects with complete metamorphosis have larval stages known by such names as maggot, grub, or caterpillar• The larval stage looks entirely different from the adult stage
    123. 123. Figure 33.37 (a) Larva (caterpillar) (b) Pupa (c) Later-stage pupa (d) Emerging adult (e) Adult
    124. 124. • Most insects have separate males and females and reproduce sexually• Individuals find and recognize members of their own species by bright colors, sound, or odors• Some insects are beneficial as pollinators, while others are harmful as carriers of diseases, or pests of crops• Insects are classified into more than 30 orders
    125. 125. Figure 33.38 Archaeognatha (bristletails; 350 species) Thysanura (silverfish; 450 species) Winged insects (many orders) Complete metamorphosis Incomplete metamorphosis Coleoptera Hemiptera (beetles; 350,000 species) (85,000 species) Diptera (151,000 species) Orthoptera (13,000 species) Hymenoptera (125,000 species) Proboscis Lepidoptera (120,000 species)
    126. 126. Crustaceans • While arachnids and insects thrive on land, crustaceans, for the most part, have remained in marine and freshwater environments • Crustaceans, subphylum Crustacea, typically have branched appendages that are extensively specialized for feeding and locomotion • Small crustaceans exchange gases through the cuticle; larger crustaceans have gills
    127. 127. • Most crustaceans have separate males and females• Isopods include terrestrial, freshwater, and marine species – Pill bugs are a well known group of terrestrial isopods• Decapods are all relatively large crustaceans and include lobsters, crabs, crayfish, and shrimp
    128. 128. Figure 33.39 (a) Ghost crab (b) Krill (c) Barnacles
    129. 129. • Planktonic crustaceans include many species of copepods, which are among the most numerous of all animals
    130. 130. Figure 33.39b (b) Krill
    131. 131. • Barnacles are a group of mostly sessile crustaceans• They have a cuticle that is hardened into a shell
    132. 132. Figure 33.39c (c) Barnacles
    133. 133. Echinoderms and chordates aredeuterostomes • Echinoderms (phylum Echinodermata) include sea stars and sea urchins • Chordates (phylum Chordata) include the vertebrates • Echinoderms and chordates constitute the clade Deuterostomia
    134. 134. • Deuterostomes share developmental characteristics – Radial cleavage – Formation of the anus from the blastopore• However, some other animals also share these developmental characteristics• Deuterostomes are defined primarily by DNA similarities
    135. 135. Figure 33.UN05 Porifera Cnidaria Lophotrochozoa Ecdysozoa Deuterostomia
    136. 136. Echinoderms • 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 and feeding • Males and females are usually separate, and sexual reproduction is external
    137. 137. Figure 33.40 Short digestive tract Stomach Anus Spine Gills Central disk Madreporite Radial nerve Digestive glands Ring Gonads canal Ampulla Podium Radial canal Tube feet
    138. 138. • Most adult echinoderms have radial symmetry with multiples of five• Echinoderm larvae have bilateral symmetry
    139. 139. • Living echinoderms are divided into five classes – Asteroidea (sea stars and sea daisies) – Ophiuroidea (brittle stars) – Echinoidea (sea urchins and sand dollars) – Crinoidea (sea lilies and feather stars) – Holothuroidea (sea cucumbers)
    140. 140. Asteroidea: Sea Stars and Sea Daisies • Sea stars have multiple arms radiating from a central disk • The undersurface of each arm bears tube feet, which grip substrate with adhesive chemicals • Sea stars feed on bivalves by prying them open with their tube feet, everting their stomach, and digesting their prey externally with digestive enzymes • Sea stars can regrow lost arms
    141. 141. • Sea daisies were discovered in 1986, and only three species are known• Sea daisies live on submerged wood and absorb nutrients through a membrane that surrounds their body
    142. 142. Figure 33.41
    143. 143. Ophiuroidea: Brittle Stars • Brittle stars have a distinct central disk and long, flexible arms, which they use for movement • Some species are suspension feeders, while others are predators or scavengers
    144. 144. Figure 33.42
    145. 145. Echinoidea: Sea Urchins and Sand Dollars • Sea urchins and sand dollars have no arms but have five rows of tube feet • Their spines are used for locomotion and protection • Sea urchins feed on seaweed using a jaw-like structure on their underside
    146. 146. Figure 33.43
    147. 147. Crinoidea: Sea Lilies and Feather Stars • Sea lilies live attached to the substrate by a stalk • Feather stars can crawl using long, flexible arms • Both are suspension feeders
    148. 148. Figure 33.44
    149. 149. Holothuroidea: Sea Cucumbers • Sea cucumbers lack spines, have a very reduced endoskeleton, and do not look much like other echinoderms • Sea cucumbers have five rows of tube feet; some of these are developed as feeding tentacles
    150. 150. Figure 33.45
    151. 151. Chordates • Phylum Chordata consists of two subphyla of invertebrates as well as hagfishes and vertebrates • Chordates are bilaterally symmetrical coelomates with segmented bodies • Chordates share many features of embryonic development with echinoderms, but have evolved separately for at least 500 million years
    152. 152. Figure 33.UN06
    153. 153. Figure 33.UN06a
    154. 154. Figure 33.UN06b
    155. 155. Figure 33.UN09 100 Moth species A Moth capture 75 rate (%) 50 Moth species B 25 0 1 2 3 4 5 6 7 Time (nights)
    156. 156. Figure 33.UN10