BIOLOGY Chapter 27 Introduction to Animal Diversity
Fig. 32-1 An Overview of Animal Diversity Multicellular Nutrition mode: Heterotrophic (ingestion) Cell structure & specialization Tissues develop from embryonic layers Nervous & Muscle (unique) Lack cell walls Collagen structural protein Mostly sexual reproduction (2N)
Fig. 32-2-2 /Fig 27.4 Reproduction and Development Cleavage Cleavage Blastula Zygote Eight-cell stage Cross section of blastula Blastocoel
Fig. 32-2-3 /Fig 27.4 Reproduction and Development Blastocoel Cleavage Cleavage Blastula Endoderm Ectoderm Zygote Eight-cell stage Cross section of blastula Blastocoel Gastrulation Blastopore Gastrula Archenteron Larval stage metamorphosis juvenile (not sexually mature) paedomorphic Homeobox direct body structure formation (235 function genes) Homeodomain Transcriptional factors HOX genes regulates body form/pattern development
Figure 27.4
100 µm Fig. 32-6 /Fig 27.4 RESULTS Wikramanayake & Martindale (2003) Site of gastrulation β-catenin Site of gastrulation
Gastrula A ectoderm B blastocoel C archenteron D endoderm E blastopore Triploblastic vs diploblastic Video: Sea Urchin Embryonic Development (Time Lapse) Figure 27.9
Figure 27.6 The phylogenetic tree of animals is based on morphological, fossil, and genetic evidence.
Figure 27.7 The (a) sponge is asymmetrical. The (b) jellyfish and (c) anemone are radially symmetrical, and the (d) butterfly is bilaterally symmetrical. (credit a: modification of work by Andrew Turner; credit b: modification of work by Robert Freiburger; credit c: modification of work by Samuel Chow; credit d: modification of work by Cory Zanker)
Fig. 32-3 /Fig 27.12 Morphological & molecular evidence Collar cells ID DNA sequences & signaling/adhesion proteins Individual choanoflagellate Choanoflagellates OTHER EUKARYOTES Sponges Animals Other animals Collar cell (choanocyte)
Figure 32.4/Fig 27.5 Choanoflagellate Hydra Fruit fly CCD domain (only found in animals) Mouse In vertebrates, the genes have been duplicated into four clusters: Hox-A, Hox-B, Hox-C, and Hox- D. Genes within these clusters are expressed in certain body segments at certain stages of development
Figure 27.12 Cells of the protist choanoflagellate resemble sponge choanocyte cells. Beating of choanocyte flagella draws water through the sponge so that nutrients can be extracted and waste removed.
Fig. 32-7Figure 27.8 Animals can be characterized by body plans Morphological and Developmental traits Bilateral symmetry: Dorsal/ventral Anterior/posterior Cephalization (a) Radial symmetry (b) Bilateral symmetry
Figure 27.10 Body Cavities (a) Coelomate = true body cavity Coelom Digestive tract (from endoderm) Body covering (from ectoderm) Tissue layer lining coelom and suspending internal organs (from mesoderm) (b) Psuedocoelomate Digestive tract (from endoderm) Body covering (from ectoderm) Muscle layer (from mesoderm) (c) Acoelomate Body covering (from ectoderm) Wall of digestive cavity (from endoderm) Pseudocoelom Tissuefilled region (from mesoderm) Key Ectoderm Mesoderm Endoderm Most triploblastic animals possess a body cavity Coelom true body cavity (from mesoderm)
Body Cavities (a) Coelomate = true body cavity Coelom Body covering (from ectoderm) Key Digestive tract (from endoderm) Ectoderm Mesoderm Endoderm Tissue layer lining coelom and suspending internal organs (from mesoderm) Coelom functions: Cushions organs Hydrostatic skeleton Internal organs growth & develop Internal organs independent movement from outer body wall
Body Cavities (b) Pseudocoelomate = mesoderm & endoderm Body covering (from ectoderm) Pseudocoelom Muscle layer (from mesoderm) Key Digestive tract (from endoderm) Ectoderm Mesoderm Endoderm
Body Cavities (c) Acoelomate = lack body cavity Body covering (from ectoderm) Tissuefilled region (from mesoderm) Key Wall of digestive cavity (from endoderm) Ectoderm Mesoderm Endoderm
Figure 27.10 Triploblasts may be (a) acoelomates, (b) eucoelomates, or (c) pseudocoelomates. Acoelomates have no body cavity. Eucoelomates have a body cavity within the mesoderm, called a coelom, which is lined with mesoderm. Pseudocoelomates also have a body cavity, but it is sandwiched between the endoderm and mesoderm. (credit a: modification of work by Jan Derk; credit b: modification of work by NOAA; credit c: modification of work by USDA, ARS)
Fig. 32-9 /Fig 27.11 Protostome development (examples: molluscs, annelids) Eight-cell stage Deuterostome development (examples: echinoderm, chordates) Eight-cell stage (a) Cleavage Key Ectoderm Mesoderm Endoderm Spiral and determinate Mesoderm Radial and indeterminate Coelom Archenteron Coelom Blastopore Solid masses of mesoderm split and form coelom. Anus Blastopore Mesoderm Folds of archenteron form coelom. Mouth (b) Coelom formation (c) Fate of the blastopore Digestive tube Mouth Mouth develops from blastopore. Anus Anus develops from blastopore.
Fig. 32-9a Protostome development (examples: molluscs, annelids) Eight-cell stage Deuterostome development (examples: echinoderms, chordates) Eight-cell stage (a) Cleavage Spiral and determinate Radial and indeterminate Platyhelminthes Identical twins & embryonic stem cells
Fig. 32-9b /Fig 27.11 Protostome development (examples: molluscs, annelids) Deuterostome development (examples: echinoderms, chordates) Coelom Archenteron Coelom (b) Coelom formation Key Ectoderm Mesoderm Endoderm Mesoderm Blastopore Blastopore Mesoderm Solid masses of mesoderm split and form coelom. Folds of archenteron form coelom.
Fig. 32-9c /Fig 27.11 Protostome development (examples: molluscs, annelids) Deuterostome development (examples: echinoderms, chordates) Anus Digestive tube Mouth (c) Fate of the blastopore Key Ectoderm Mesoderm Endoderm Mouth Anus Mouth develops from blastopore. Anus develops from blastopore.
Fig. 32-9 /Fig 27.11 Protostome development (examples: molluscs, annelids) Eight-cell stage Deuterostome development (examples: echinoderm, chordates) Eight-cell stage (a) Cleavage Key Ectoderm Mesoderm Endoderm Spiral and determinate Mesoderm Radial and indeterminate Coelom Archenteron Coelom Blastopore Solid masses of mesoderm split and form coelom. Anus Blastopore Mesoderm Folds of archenteron form coelom. Mouth (b) Coelom formation (c) Fate of the blastopore Digestive tube Mouth Mouth develops from blastopore. Anus Anus develops from blastopore.
Figure 27.11 Eucoelomates: divided into two groups based on their early embryonic development Protostomes Deuterostomes
Figure 32.10 Views of animal phylogeny Porifera ANCESTRAL COLONIAL FLAGELLATE Metazoa Eumetazoa Bilateria Deuterostomia Protostomia Cnidaria Ctenophora Ectoprocta Brachiopoda Echinodermata Chordata Platyhelminthes Rotifera Mollusca Annelida Morphological & developmental data Arthropoda Nematoda
Figure 32.11 Views of animal phylogeny Porifera ANCESTRAL PROTIST Metazoa 770 million years ago Eumetazoa 680 million years ago Points of agreement: Common ancestor Sponge basal animal Eumetazoan true tissues Bilateria most animals Molecular data Bilateria 670 million years ago Ctenophora Cnidaria Acoela Hemichordata Echinodermata Chordata Platyhelminthes Rotifera combine morphological, molecular & fossil data Deuterostomia Lophotrochozoa Ecdysozoa Ectoprocta Brachiopoda Mollusca Annelida Nematoda Arthropoda
Fig. 32-13 100 µm Lophophore Apical tuft of cilia Mouth Anus (a) An ectoproct (b) Structure of a trochophore larva
The Diversification of Animals Five important points about the relationships among living animals are reflected in their phylogeny 1. All animals share a common ancestor 2. Sponges are basal animals 3. Eumetazoa ( true animals ) is a clade of animals with true tissues 4. Most animal phyla belong to the clade Bilateria 5. There are three major clades of bilaterian animals all of are invertebrates except Chordata
Figure 32/ /Fig 27.14 Era 535 525 mya: Cambrian explosion 565 mya: Ediacaran biota 365 mya: Early land animals Origin and diversification of dinosaurs Diversification of mammals Neoproterozoic Paleozoic Mesozoic Cenozoic 1,000 542 251 65.5 0 Millions of years ago (mya)
Fig. 32-4 /Fig 27.15 Neoproterozoic Era Ediacara 1.5 cm 0.4 cm Bore hole (a) Mawsonites spriggi (b) Spriggina floundersi 0.1 mm
Fig. 32-5/Fig 27.16 Paleozoic Era Cambrian explosion & Ediacaran decline pred-prey Increase O 2 HOX genes Hallucigenia fossil (530 mya)
Figure 27.17 fossil (a d) trilobites, extinct arthropods that appeared in the early Cambrian period, 525 million years ago, and disappeared from the fossil record during a mass extinction at the end of the Permian period, about 250 million years ago.
Table 25-1 Animal diversity increased Punctuated mass extinctions
Fig. 32-UN1 Common ancestor of all animals Sponges (basal animals) Ctenophora Cnidaria Eumetazoa Metazoa True tissues Bilateral summetry Three germ layers Acoela (basal bilaterians) Deuterostomia Lophotrochozoa Ecdysozoa Bilateria (most animals)