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Which numbers represent chordates and which numbers represent invertebrates? PowerPoint Presentation
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Which numbers represent chordates and which numbers represent invertebrates?

Which numbers represent chordates and which numbers represent invertebrates?

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Which numbers represent chordates and which numbers represent invertebrates?

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  1. 1. 2. 3. Which numbers represent chordates and which numbers represent invertebrates? 4. 5. 6. 7.

  2. 25.2 Animal Body Plans and Evolution

  3. Features of Body Plans • Each animal phylum has a unique organization of particular body structures that is often referred to as a body plan. • Features of body plans include: • Levels of organization • Body symmetry • Differentiation of germ layers • Formation of body cavities • Patterns of embryonic development • Segmentation • Cephalization • Limb formation

  4. Levels of Organization • Animals have specialized cells that are organized into tissues. • There are several types of tissues found in animals: • Epithelial tissues- cover body surfaces inside and out, are also thin and flat. • Example: epithelial tissues line lungs and allow gases to easily diffuse through • Muscle tissues • Connective tissues • Tissues combine during growth and development to form organs and organ systems to carry out complex functions

  5. Body Symmetry • Bodies of most animals exhibit some sort of symmetry • There are two different forms of symmetry • Radial symmetry: any number of imaginary planes drawn through the center of the body could divide into equal halves. Example: Sea anemone • Bilateral symmetry: a single imaginary plane divides the body into left and right sides that are mirror images of each other. • Animals with bilateral symmetry have the following • A definite front: also known as the anterior • A definite end: also known as the posterior • An upper side: also known as the dorsal side • A lower side: also known as the ventral side

  6. Differentiation of Germ Layers • During embryological development the cells of most animal embryos differentiate into 3 germ layers • 1. Endoderm: the innermost germ layer, develops into linings of the digestive tract and much of the respiratory system • 2. Mesoderm: the middle layer, gives rise to the muscles and much of the circulatory, reproductive, and excretory organ systems • 3. Ectoderm: the outermost layer, produces sense organs, nerves, and the outer layer of skin

  7. Formation of a Body Cavity • Most animals have a body cavity, which is a fluid-filled space between the digestive tract and body wall • Body cavities provide space for internal organs to suspend and room for organs to grow • Most complex animal phyla have a true coelom- a body cavity that develops within the mesoderm and is completely lined with tissue derived from the mesoderm • The coelom wraps around the gut and internal organs are suspended in it • Animals with a coelom allows the animals to move without damaging the internal organs or interfering with the organ’s function • Acoelomates are invertebrates that lack a coelom • The are of an acoelomate’s body wall and gut is completely filled with tissues • Some invertebrate groups have a pseudocoelom, which is only partially lined with mesoderm • This false coelom is filled with liquid that can act like a skeleton and provide support

  8. Patterns of Embryological Development • Every animal that reproduces begins as a zygote (a fertilized egg) • At the beginning of development a zygote forms a blastula, which is a hollow ball of cells like an inflated balloon • The blastula develops into the digestive tract by folding in on itself and developing a long elongated tube that runs from one end to the other • In the beginning the digestive tract has only one opening, called the blastopore

  9. Patterns of Embryological Development • An efficient digestive system needs two openings: a mouth through which food enters and an anus through which waste exits • Protostomes: the blastopore becomes the mouth and the anus becomes the second opening, which develops at the opposite end of the tube • Examples: flatworms, earthworms, snails, clams, spiders, and insects • Deuterotomes: the blastopore becomes the anus, and the mouth is formed from the second opening that develops • Chordates and echinoderms (sea stars) are deuterotomes, which indicates that echinoderms are closely related to chordates

  10. Segmentation: Repeating Parts • Segmentation occurs as many bilateral symmetrical animals develop, their bodies become divided into numerous repeated parts, or segments • Segmented animals such as worms, insects, and vertebrates have at least some internal and external body parts that repeat on each side of the body • The most successful animals, including humans, have bilateral symmetry and segmentation

  11. Cephalization: Head Formation • Animals with bilateral symmetry typical exhibit cephalization- the concentration of sense organs and nerve cells at their anterior end • The most successful animals including arthropods and vertebrates exhibit pronounced cephalization • Insect and vertebrate embryos heads are formed by fusion and specialization of several body segments during development • As the segments fuse the external and internal parts combine in ways that concentrate sense organs in the head, such as the eyes • Nerve cells that process information and “decide” what an animal should do are also found in the head • Animals with a head move in a head first direction because this way the concentration of sense organs and nerve cells come in contact with the new environment first

  12. Limb Formation: Legs, Flippers, and Wings • Segmented, bilaterally symmetrical animals typically have appendages on both sides of the body. • The types of appendages vary depending on the animal. Examples: • Bristles in worms * Flippers in dolphins • Jointed legs in spiders * Wings in dragonflies • These different kinds of appendages have evolved several times, and have been lost several times, in various animal groups • Limb formation and segmentation have evolved to allow animals to be more flexible and have improved movement

  13. Limb Formation: Legs, Flippers, and Wings

  14. Animals to include on chart: • Sponges *Cnidarians • Flatworms *Roundworms • Annelids *Mollusks • Arthropods *Echinoderms • Chordates

  15. 25.2 Body Plans and Evolution Vocabulary • Radial Symmetry: any number of imaginary planes drawn through the center of the body could divide into equal halves. • Bilateral Symmetry: a single imaginary plane divides the body into left and right sides that are mirror images of each other. • Endoderm: the innermost germ layer, develops into linings of the digestive tract and much of the respiratory system • Mesoderm: the middle layer, gives rise to the muscles and much of the circulatory, reproductive, and excretory organ systems • Ectoderm: the outermost layer, produces sense organs, nerves, and the outer layer of skin • Coelom: a body cavity that develops within the mesoderm and is completely lined with tissue derived from the mesoderm

  16. 25.2 Body Plans and Evolution Vocabulary • Pseudocoelom: which is only partially lined with mesoderm • Zygote: a fertilized egg • Blastula: a hollow ball of cells like an inflated balloon that develops into the digestive tract by folding in on itself and developing a long elongated tube that runs from end to the other • Protostomes: the blastopore becomes the mouth and the anus becomes the second opening, which develops at the opposite end of the tube • Deuterostomes: the blastopore becomes the anus, and the mouth is formed from the second opening that develops • Cephalization: the concentration of sense organs and nerve cells at their anterior end

  17. 25.2 Assessment • 1a. List eight features of animal body plans. • 1b. How is the embryology of echinoderms similar to that of vertebrates? What might this similarity indicate about their evolutionary relationship.