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Lecture 021. Animal Body Plans. Criteria for Evolutionary Development & Classification. Cellular organization Symmetry Coelom Digestive system Segmentation Cephalization. Kingdom Animalia. Symmetry Unorganized Radial Bilateral Cellular organization Tissues, organs, systems.
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Lecture 021 Animal Body Plans
Criteria for Evolutionary Development & Classification Cellular organization Symmetry Coelom Digestive system Segmentation Cephalization
Kingdom Animalia • Symmetry • Unorganized • Radial • Bilateral • Cellular organization • Tissues, organs, systems
Kingdom Animalia coelom digestive tube • Coelom • Body cavity or not • Digestive system • None, 1 or 2 openings, how
Kingdom Animalia • Segmentation • Repetition of body parts • Cephalization • Development of a “head end”
What to Remember Match with common name General characteristics Special evolutionary features General evolutionary location
Geologic Time Scale Millions of Years end of dinosaurs 1st dinosaur 1st reptiles 1st amphibians 1st land plants 1st fish 1st invertebrates
Ediacaran Fauna: distinctive group of fossils dating from and existing only during Precambrian time • 600 mya • Australia's Ediacara Hills • Environment: shallow seas • Description: soft bodies; worms, cnideria • May be an evolutionary dead end
Reconstruction of the sea floor during the Vendian times when the Ediacaran organisms thrived
Ediacaran Seas Sea pens Mostly cnidarians and worms
Ancient Seas at the During the Cambrian Radiation (540 MYBP) Burgess Shale
Ancient Seas at the During the Cambrian Radiation(540 MYBP) Drawings based on fossils collected from Burgess Shale in British Columbia, Canada
Burgess Shale Fauna(540 MYBP) Feeding tentacles Hallucigena spines Similar to a sea urchin An explosion of body plans
Burgess Shale Fauna(540 MYBP) Pikaia- earliest known chordate
Anomalocaris Burgess Shale Fauna(540-530 MYBP Opabinia Wiwaxia
Phylogentic Relationships of Animals Platyhelminthes Porifera Mollusca Chordata Arthropoda Annelida Cnideria Nematoda Echinodermata pseudocoelom segmentation acoelom Protostome: schizocoelem Deuterostomes: eucoelom radial symmetry bilateral symmetry no true tissues true tissue Ancestral Protist
Major Stages of Animal Development • gametogenesis • fertilization • cleavage • blastula • gastrulation • differentiation and morphogenesis
Hypothetical Scheme for the Origin of Multicellularity in Animals
Protostome vs Deuterostome Blastula • Protostome: blastopore becomes mouth • Deuterostome: blastopore becomes anus Blastopore
Some Examples of Animal Phyla • Phylum Cnidaria • sea anemones, corals, jellyfish, man-of-wars & hydroids • Phylum Mollusca • snails, slugs, chitons, clams, oysters, octopods & squids • Phylum Arthropoda • spiders, scorpions, crabs, shrimp, insects & centipedes • Phylum Echinodermata • sea stars, sea urchins, sea cucumbers & sea lilies • Phylum Chordata • sea squirts, fish, amphibian, reptiles, birds & mammals
Major Body Plan Characteristics of Animals • Symmetry • Primary Germ Layers • Gut Organization • Body Cavity • Segmentation • Skeletal Systems • Circulatory Systems • Appendages • Coloniality
Symmetry • Asymmetry • Radial Symmetry • Bilateral Symmetry
Symmetry Bilateral Symmetry Radial Symmetry
Radial Symmetry JellyfishPhylum Cnidaria
Pentamerous Radial Symmetry Sea StarsPhylum Echinodermata
Bilateral Symmetry SlugPhylum Mollusca
Bilateral Symmetry SquidPhylum Mollusca
Primary Germ Layers Mesoderm • None • Diploblastic • Triploblast gut Ectoderm Endoderm
Fates of the Primary Germ Layers • Ectoderm • hair, nails, epidermis, brain, nerves • Mesoderm • notochord (in chordates), dermis, blood vessels, heart, bones, cartilage, muscle • Endoderm • internal lining of the gut and respiratory pathways, liver, pancreas
Germ Layer Patterns Endoderm Diploblastic gut Ectoderm
Diploblastic- two germ layers Phylum Cnidaria
Germ Layer Patterns Mesoderm Triploblastic: 3 germ layers gut Ectoderm Endoderm acoelomate
Gut Organization • No Gut • Blind Sac Gut • Complete Gut
No Gut SpongesPhylum Porifera
No Gut SpongesPhylum Porifera
Blind Sac Gut Phylum Cnidaria
Body Cavities • Acoelomate • Eucoelomate • Pseudocoelomate
Body Cavities Mesoderm Acoelomate- lacks cavity between gut and outer body wall gut Ectoderm Endoderm
Body Cavities coelom Mesoderm Eucoelomate- body cavity completely lined with mesoderm gut Ectoderm Endoderm
Body Cavities pseudocoelom Mesoderm Pseudocoelomate: body cavity partially lined with mesoderm gut Endoderm Ectoderm
Advantages of aFluid-Filled Body Cavity • hydrostatic skeleton • greater freedom for internal organs • greater body size because of body fluid circulation