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Introduction to Animals

Introduction to Animals. Chapter 27. Characteristics of Animals A. General Features of Animals:. Section 25.1 Summary – pages 673 - 679. 1. One characteristic common to all animals is that they are heterotrophic , meaning they must consume food to obtain energy and nutrients.

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Introduction to Animals

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  1. Introduction to Animals • Chapter 27

  2. Characteristics of Animals • A. General Features of Animals: Section 25.1 Summary – pages 673 - 679 • 1. One characteristic common to all animals is that they are heterotrophic, meaning they must consume food to obtain energy and nutrients. • All animals depend either directly or indirectly on autotrophs for food. • In some animals, digestion is carried out within individual cells; in other animals, digestion takes place in an internal cavity.

  3. 2. Mobility- • Can perform rapid, complex movements • Move by means of muscle cells, specialized cells that are able to contract with considerable force. • Animals can swim, crawl, walk, run and even fly. Section 25.1 Summary – pages 673 - 679 • Animals are organisms with ways of moving that help them reproduce, obtain food, and protect themselves.

  4. 3. Multicellularity: Section 25.1 Summary – pages 673 - 679 • Most animals have specialized cells that form tissues and organs—such as nerves and muscles. • Animals are composed of cells that do not have cell walls. • The body size does not matter all of the cells are similar in size. • Advantage : individual cells can specialize in one life task.

  5. Section 25.1 Summary – pages 673 - 679 4. Diploidy • Meaning adults have two copies of each chromosome. • One inherited from mother and one from father. • Only their gametes are haploid. • Advantage- is that it permits an animal to exchange genes between the two copies of a set of chromosomes, creating new combinations of genes.

  6. Section 25.1 Summary – pages 673 - 679 5. Sexual Reproduction/Fertilization • Most animals reproduce sexually by producing gametes. • Male animals produce sperm cells (which are smaller and have a flagella for moving) and female animals produce egg cells. • Fertilization occurs when a sperm cell penetrates the egg cell, forming a new cell called a zygote. • In animals, fertilization may be internal or external.

  7. Section 25.1 Summary – pages 673 - 679 6. Absence of a Cell Wall • Animals do not have a cell wall. • This characteristic has allowed animals mobility that other multi-cellular organisms do not have. • Cells move about in animals bodies all the time. • Cells called macrophages , act as mobile garbage collectors, crawling over tissues and removing debris.

  8. Section 25.1 Summary – pages 673 - 679 7. Blastula Formation/Cell division • The zygote divides by mitosis and cell division to form two cells in a process called cleavage. cleavage • Once cell division has begun, the organism is known as an embryo.

  9. Section 25.1 Summary – pages 673 - 679 Cell division • The two cells that result from cleavage then divide to form four cells and so on, until a cell-covered, fluid-filled ball called a blastula is formed. • The blastula is formed early in the development of an animal embryo.

  10. Section 25.1 Summary – pages 673 - 679 Gastrulation • After blastula formation, cell division continues. • The cells on one side of the blastula then move inward to form a gastrula—a structure made up of two layers of cells with an opening at one end.

  11. Section 25.1 Summary – pages 673 - 679 Gastrulation • The cells at one end of the blastula move inward, forming a cavity lined with a second layer of cells. • The layer of cells on the outer surface of the gastrula is called the ectoderm. • The layer of cells lining the inner surface is called the endoderm.

  12. Section 25.1 Summary – pages 673 - 679 Gastrulation Ectoderm • The ectoderm cells of the gastrula continue to grow and divide, and eventually they develop into the skin, nervous tissue, sense organs such as eyes of the animal.

  13. Section 25.1 Summary – pages 673 - 679 Gastrulation • The endoderm cells develop into the lining of the animal’s digestive tract and into organs associated with digestion. Endoderm

  14. Section 25.1 Summary – pages 673 - 679 Formation of mesoderm • Mesoderm is found in the middle of the embryo; the term meso means “middle.” Mesoderm • The mesoderm is the third cell layer found in the developing embryo between the ectoderm and the endoderm.

  15. Section 25.1 Summary – pages 673 - 679 Formation of mesoderm • The mesoderm cells develop into the muscles, circulatory system, excretory system, and, in some animals, the respiratory system.

  16. Section 25.1 Summary – pages 673 - 679 Sperm cells Cell Differentiation in Animal Development Fertilization Egg cell Formation of mesoderm First cell division Endoderm Mesoderm Ectoderm Gastrulation Additional cell divisions Formation of a blastula

  17. Section 25.1 Summary – pages 673 - 679 8. Tissue • Cells are organized into structural and functional units called tissues. (except in sponges) • Tissue- are groups of cells with a common structure that work together to perform a specific function. • Ex: Adipose tissue- store fat Muscle tissue- contract- producing movement. Nerve tissue- conduct signals.

  18. Section 25.2 Summary – pages 680 - 685 B. Body Symmetry • Symmetry isa term that describes the arrangement of body structures. • Different kinds of symmetry enable animals to move about in different ways.

  19. Section 25.2 Summary – pages 680 - 685 1 . Asymmetry • An animal that is irregular in shape has no symmetry or an asymmetrical body plan. • Animals with no symmetry often are sessile organisms that do not move from place to place. • Most adult sponges have the simplest body form anddo not move about.

  20. Section 25.2 Summary – pages 680 - 685 Asymmetry • The bodies of most sponges consist of two layers of cells. • Unlike all other animals, a sponge’s embryonic development does not include the formation of an endoderm and mesoderm, or a gastrula stage.

  21. Section 25.2 Summary – pages 680 - 685 2. Radial symmetry • Animals with radial symmetry can be divided along any plane, through a central axis, into roughly equal halves. • Radial symmetry is an adaptation that enables an animal to detect and capture prey coming toward it from any direction.

  22. Section 25.2 Summary – pages 680 - 685 Radial symmetry • A hydra develops from just two embryonic cell layers—ectoderm and endoderm. • Most are aquatic, move slowly or drift in ocean currents. Inner cell layer Outer cell layer

  23. Section 25.2 Summary – pages 680 - 685 3. Bilateral symmetry • An organism with bilateral symmetry can be divided down its length into similar right and left halves.

  24. Section 25.2 Summary – pages 680 - 685 Bilateral symmetry • Bilaterally symmetrical animals can be divided in half only along one plane. • In bilateral animals, the anterior, or head end, often has sensory organs. • The posterior of these animals is the tail end. • The dorsal, or upper surface, also looks different from the ventral, or lower surface.

  25. Bilateral Symmetry and Body Plans Section 25.2 Summary – pages 680 - 685 • Animals with bilateral symmetry have become specilized in different ways, for example , they have an anterior concentration of sensory structures and nerves, a process called cephalization. • With sensory organs concentrated in the front, such animals can more easily sense food and danger. • All bilaterally symmetrical animals developed from three embryonic cell layers—ectoderm, endoderm, and mesoderm.

  26. Section 25.2 Summary – pages 680 - 685 C. Internal Body Cavity: • Some bilaterally symmetrical animals also have fluid-filled spaces inside their bodies called body cavities (coelom) in which internal organs are found. • 1. acoelomate- Animals that develop from three cell layers—ectoderm, endoderm, and mesoderm—but have no body cavities . • They have a digestive tract that extends throughout the body.

  27. Section 25.2 Summary – pages 680 - 685 Acoelomates Acoelomate Flatworm • Flatworms are bilaterally symmetrical animals with solid, compact bodies. Like other acoelomate animals, the organs of flatworms are embedded in the solid tissues of their bodies. Ectoderm Mesoderm Endoderm Body cavity Digestive tract

  28. Section 25.2 Summary – pages 680 - 685 Acoelomates Acoelomate Flatworm • A flattened body and branched digestive tract allow for the diffusion of nutrients, water, and oxygen to supply all body cells and to eliminate wastes. Ectoderm Mesoderm Endoderm Body cavity Digestive tract

  29. 2. Pseudocoelomates Section 25.2 Summary – pages 680 - 685 Pseudocoelomate Roundworm • A roundworm is an animal with bilateral symmetry. Ectoderm Mesoderm Endoderm • The body of a roundworm has a space that develops between the endoderm and mesoderm. Body cavity Digestive tract

  30. Section 25.2 Summary – pages 680 - 685 Pseudocoelomates Pseudocoelomate Roundworm • It is called a pseudocoelom—a fluid-filled body cavity partly lined with mesoderm. Ectoderm Mesoderm Endoderm Body cavity Digestive tract Pseudocoelom

  31. Section 25.2 Summary – pages 680 - 685 Pseudocoelomates • Pseudocoelomates can move quickly. • Although the roundworm has no bones, it does have a rigid, fluid-filled space, the pseudocoelom. • Its muscles attach to the mesoderm and brace against the pseudocoelom.

  32. Section 25.2 Summary – pages 680 - 685 Pseudocoelomates • Pseudocoelomates have a one-way digestive tract that has regions with specific functions. • The mouth takes in food, the breakdown and absorption of food occurs in the middle section, and the anus expels waste. Intestine Anus Mouth Round body shape

  33. Section 25.2 Summary – pages 680 - 685 3. Coelomates Coelomate Segmented Worm • The body cavity of an earthworm develops from a coelom, a fluid-filled space that is completely surrounded by mesoderm. Ectoderm Mesoderm Endoderm Body cavity Digestive tract • The greatest diversity of animals is found among the coelomates. Coelom

  34. Section 25.2 Summary – pages 680 - 685 Coelomates • In coelomate animals, the digestive tract and other internal organs are attached by double layers of mesoderm and are suspended within the coelom. • The coelom cushions and protects the internal organs. It provides room for them to grow and move independently within an animal’s body.

  35. D. Body Segmentation Section 25.2 Summary – pages 680 - 685 • Segmented animals are composed of a series of repeating, similar units called segments. • You can observe segmentation in some animals such as earthworms, crustaceans, spiders and insects. • In vertebrates, segments are not visible externally, but there is evidence in a vertebrae embryo. • Vertebrae muscles develop from repeated blocks of tissue called somites. • The backbone consists of a stack of very similar vertebrae.

  36. Body Segmentation Section 25.2 Summary – pages 680 - 685 • In segmented animals each segment can move independently. However, they are not totally independent of each other because materials pass from one segment to another through a circulatory and nervous system that connects them. • Therefore, they have great flexibility and mobility. • Each segment repeats many of the organs in the adjacent segment, as a result an injured animal can still perform vital life functions. • Segmentation also offers evolutionary flexibility.

  37. E. Kinds of Animals Section 25.2 Summary – pages 680 - 685 • Kingdom Animalia- contain about 35 major divisions called phyla. (singular Phylum) • Scientists use a Phylogenetic Tree – to show how animals are related through evolution. • They compare: • 1. anatomy and physiology • 2. patterns of development in embryos • 3. DNA • The animal Kingdom is often divided into two groups Invertebrates and Vertebrates.

  38. II. Animal Body Systems: Section 25.2 Summary – pages 680 - 685 • A. Tissues and Organs – have evolved to carry out and specialize to perform specific functions. 6 - Important functions of these tissues and organs are: Digestion Respiration Circulation Conduction of nerve impulses Support Excretion

  39. 1. Digestion Section 25.2 Summary – pages 680 - 685 a.) Single celled organisms and Sponges digest their food within their body cells. intracellularly b.) Other simple animals digest their food extracellularly (outside their body cells) within a digestive cavity. • Gastrovascular cavity – a digestive cavity with only one opening. ( hydra and flatworm) • There can be no specialization within a gastrovascular cavity because every cell in exposed to all stages of food digestion. c.) Other animals have a digestive tract (gut) withtwo openings, a mouth and an anus. • This one way digestive tract allows for specialization. (food storage, breaking down, chemical , absorption.)

  40. 2. Respiration- the uptake of oxygen and the release of carbon dioxide. Section 25.2 Summary – pages 680 - 685 a.) Can take place only across a moist surface, such as damp skin of an earthworm. (diffusion) b.) Larger, more complex animals have specialized structures. • gills-very thin projections of tissue that are rich in blood vessels. (provide a large surface area for gas exchange) • Lungs –allow terrestrial animals to respire on dry land.

  41. 3. Circulation-transports oxygen and nutrients to body cells. Section 25.2 Summary – pages 680 - 685 a.) Open Circulatory System- a heart pumps fluid containing oxygen and nutrients through a series of vessels out into the body cavity. • Fluid washes across the bodies tissues.The fluid collects in open spaces and flows back to the heart. Ex: crayfish b.)Closed Circulatory System-a heart pumps blood through a system of blood vessels. • The blood remains in the vessels and does not come in direct contact with the body’s tissues. • Materials pass into and out of the blood by diffusing through the walls of the blood vessels.

  42. 4. Conduction of Nerve Impulses Section 25.2 Summary – pages 680 - 685 a.) Nerve Cells (neurons) are specialized for carrying messages in the form of electrical impulses. (Conduction) • These cells coordinate the activities in an animals body. • 1. Nerve net- all nerve cells are similar and linked together in a web. (ex: hydra,jellyfish) • 2. ganglia- clusters of neurons that form a brain like structure.( ex: flatworm) • 3. brains- more complex invertebrates have brains with sensory structures, such as eyes, associated with them. • These cephalized animals interact with their environment in more complex ways. (ex: grasshopper – human)

  43. 5. Support Section 25.2 Summary – pages 680 - 685 • An animals skeleton provides a framework that supports its body and is vital to movement. a.Hydrostatic skeleton- consists of water that is contained under pressure in a closed cavity. It is formed by the gastrovascular cavity. (ex: hydra, earthworm.) b.) Exoskeleton- a rigid external skeleton that encases the body of an animal. • The muscles are attached to the inside of the skeleton, which provides a surface for them to pull against.

  44. Section 25.2 Summary – pages 680 - 685 • Exoskeletons also protect soft body tissues, prevent water loss, and provide protection from predators. • As an animal grows, it secretes a new exoskeleton and sheds the old one. • Exoskeletons are often found in invertebrates. An invertebrate is an animal that does not have a backbone.

  45. Section 25.2 Summary – pages 680 - 685 • C. Endoskeleton- is composed of a hard material, such as bone, embedded within an animal. • Invertebrates, such as sea urchins and sea stars, have an internal skeleton called an endoskeleton. It is covered by layers of cells and provides support for an animal’s body.

  46. Section 25.2 Summary – pages 680 - 685 • The endoskeleton protects internal organs and provides an internal brace for muscles to pull against.

  47. Section 25.2 Summary – pages 680 - 685 • An endoskeleton may be made of calcium carbonate, as in sea stars; cartilage, as in sharks; or bone. Calcium carbonate cartilage

  48. Section 25.2 Summary – pages 680 - 685 • Bony fishes, amphibians, reptiles, birds, and mammals all have endoskeletons made of bone. bone

  49. Section 25.2 Summary – pages 680 - 685 • A vertebrate is an animal with an endoskeleton and a backbone. All vertebrates are bilaterally symmetrical.

  50. 6. Excretion- the removal of wastes produced by cellular metabolism. (ammonia) • a.)Diffusion-through skin or gills (fish and some aquatic invertebrates) • This is effective but they lose a lot of water. • Terrestrial animals need to minimize water loss- they do so by: • b.) Converting ammonia to nontoxic chemicals, like urea. • Water and other useful substances are returned to the body in this process. • Kidney’s filter fluid from the blood and excrete them as concentrated urine. Section 25.2 Summary – pages 680 - 685

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