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1. Apply Concepts Design a “new” invertebrate. Create and illustration on which you point out its body plan features. Then show its place on the cladogram.

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Presentation on theme: "1. Apply Concepts Design a “new” invertebrate. Create and illustration on which you point out its body plan features. Then show its place on the cladogram."— Presentation transcript:

1 1. Apply Concepts Design a “new” invertebrate. Create and illustration on which you point out its body plan features. Then show its place on the cladogram of invertebrates and write a caption explaining how its features helped you decide where it belongs.

2 CH 26 ANIMAL EVOLUTION AND DIVERSITY 26.1 Invertebrate Evolution and Diversity

3  Fossil evidence indicates that the first animals began evolving long before the Cambrian Explosion.

4 Origins of the Invertebrates  Roughly 3 billion years after the first prokaryotic cells evolved, all prokaryotes and eukaryotes were single-celled  Animals evolved from ancestors they shared with organisms called choanoflagellates  Single-celled eukaryotes that sometimes grow in colonies  Similar to sponges.

5 Traces of Early Animals  Oldest evidence of multicellular life comes from microscopic fossils that are roughly 600 million years old  First animals were tiny and soft-bodied, so few fossilized bodies exist.

6 Ediacaran Fauna  Before the Cambrian Period  From the Ediacara Hills of Australia  Fossils 565 to about 544 million years old  Flat and lived on the bottom of shallow seas  Little evidence of cell, tissue, or organ specialization, and no organization into a front and back end.

7 Cambrian Explosion  Cambrian Period began about 542 million years ago  Burgess Shale of Canada  Fossils show that over a period of 10–15 million years, animals evolved complex body plans, including specialized cells, tissues, and organs.

8  By the end of the Cambrian Period, all the basic body plans of modern phyla had been established  Later evolutionary changes, which produced the more familiar body structures of modern animals, involved variations on these basic body plans.

9  Invertebrates are the most abundant animals on Earth.

10 Sponges  Phylum: Porifera  Most ancient members of the kingdom Animalia  Multicellular, heterotrophic, lack cell walls, and contain a few specialized cells.

11 Cnidarians  Phylum: Cnidaria  Includes jellyfishes, sea fans, sea anemones, hydras, and corals  Aquatic, soft-bodied, carnivorous, radially symmetrical animals with stinging tentacles arranged in circles around their mouths.

12 Arthropods  Phylum: Arthropoda  Includes spiders, centipedes, insects, and crustaceans  Bodies divided into segments, a tough external skeleton called an exoskeleton, cephalization, and jointed appendages (legs and antennae)  Appeared in the sea about 600 million years ago.

13 Nematodes (Roundworms)  Phylum: Nematoda  Unsegmented worm with pseudocoeloms, specialized tissues and organ systems, and digestive tracts with two openings  More closely related to the arthropods than flatworms.

14 Flatworms  Phylum: Platyhelminthes  Soft, unsegmented, flattened worms that have tissues and internal organ systems  Simplest animals to have three embryonic germ layers, bilateral symmetry, and cephalization  No coelms.

15 Annelids  Phylum: Annelida  Includes earthworms, some marine worms, and leeches  Worms with segmented bodies and a true coelom.

16 Mollusks  Phylum: Mollusca  Includes snails, slugs, clams, squids, and octopi  Soft-bodied animals that have an internal or external shell  Have true coeloms and complex organ systems  May have a trochophore  Immature free-swimming larva stage.

17 Echinoderms  Phylum: Echinodermata  Includes sea stars, sea urchins, and sand dollars  Have spiny skin and an internal skeleton  Have a water vascular system that include suction- cuplike tube feet  Deuterostomes.


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