Chapter: Animals

2. Table of Contents Chapter: Animals Section 1: What is an animal? Section 2: Invertebrate Animals Section 3: Vertebrate Animals

3. What is an animal? 1 Animal Characteristics • What makes an animal an animal? • Animals are many-celled organisms that are made of different kinds of cells. • Most animal cells have a nucleus and organelles. The nucleus and many organelles are surrounded by a membrane. This type of cell is called a eukaryotic (yew ker ee AH tihk) cell.

4. What is an animal? 1 Animal Characteristics • Animals cannot make their own food. • Animals digest their food. • Most animals can move from place to place.

5. What is an animal? • Symmetryrefers to the arrangement of the individual parts of an object that can be divided into similar halves. 1 Symmetry • Animals with body parts arranged in a circle around a central point have radial symmetry.

6. What is an animal? 1 Symmetry • Animals with bilateral symmetry have parts that are nearly mirror images of each other. • A line can be drawn down the center of their bodies to divide them into two similar parts.

7. What is an animal? 1 Symmetry • Some animals have an irregular shape. • They are called asymmetrical (AY suh meh trih kul). • They have bodies that cannot be divided into similar halves.

8. What is an animal? 1 Animal Classification • Scientists place all animals into smaller, related groups. • They can begin by separating animals into two distinct groups—vertebrates and invertebrates. • Vertebrates (VUR tuh bruts) are animals that have a backbone.

9. What is an animal? 1 Animal Classification • Invertebrates (ihn VUR tuh bruts) are animals that do not have a backbone. • About 97 percent of all animals are invertebrates.

10. What is an animal? 1 Animal Classification • Scientists classify the invertebrates into smaller groups, as shown. • The animals within each group share similar characteristics.

11. Section Check 1 Question 1 How do animals get food? Answer Animals can not make their own food. They must eat plants or other animals to supply their energy needs. GLE 0707.Inq.5

12. Section Check 1 Question 2 Which has radial symmetry? A. lobster B. sea anemone C. sponge D. none of them GLE 0707.Inq.5

13. Section Check 1 Answer The sea anemone has radial symmetry. Symmetry refers to the arrangement of the parts of an animal. Animals with radial symmetry have body parts arranged in a circle around a central point. GLE 0707.Inq.5

14. Section Check 1 Question 3 Which describes most of the cells found in animals? A. they have bilateral symmetry B. they have a nucleus and many organelles C. they help animals move D. they help in reproduction GLE 0707.1.1 SPI 0707.1.1

15. Section Check 1 Answer The correct answer is B. The cells found in animals are called eukaryotic cells. Animals are made of many different kinds of cells. GLE 0707.1.1 SPI 0707.1.1

16. Invertebrate Animals 2 Sponges • Adult sponges are sessile meaning they remain attached to one place. • They are filter feeders, filtering food out of the water that flows through their bodies.

17. Invertebrate Animals 2 Sponges • Sponge bodies are made of two layers of cells. • The inner surface of the central cavity is lined with collar cells. • Thin, whip-like structures called flagella extend from the collar cells and keep the water moving through the sponge.

18. Invertebrate Animals 2 Body Support and Defense • The soft bodies of many sponges are supported by sharp, glass-like structures called spicules. • Other sponges have a material called spongin. Spongin is similar to foam rubber because it makes sponges soft and elastic.

19. Invertebrate Animals 2 Sponge Reproduction • Sponges care reproduce asexually and sexually. Asexual reproduction occurs when a bud on the side of the parent sponge develops into a small sponge.

20. Invertebrate Animals 2 Cnidarians • Cnidarians such as jellies, sea anemones, hydra, and corals, have tentacles surrounding their mouth. • Cnidarians are hollow-bodied animals with two cell layers that are organized into tissues. The inner layer forms a digestive cavity where food is broken down.

21. Invertebrate Animals 2 Cnidarians • Cnidarians reproduce asexually and sexually. Some reproduce asexually by budding. • Some can reproduce sexually by releasing eggs or sperm into the water.

22. Invertebrate Animals 2 Flatworms and Roundworms • Flatworms are invertebrates with long, flattened bodies ant bilateral symmetry. • Their soft bodies have three layers of tissue organized into organs and organ systems.

23. Invertebrate Animals 2 Flatworms and Roundworms • A roundworm’s body is described as a tube within a tube, with a fluid-filled cavity in between the two tubes. • Their digestive tract has two openings. Food enters through the mouth, is digested in a digestive tract, and wastes exit through the anus.

24. Invertebrate Animals 2 Mollusks • Mollusks are soft-bodied invertebrates that usually have a shell. They also have a mantle and a large, muscular foot. • If the mollusk has a shell, it is secreted by the mantle. • The foot is used for moving or for anchoring the animal.

25. Invertebrate Animals 2 Mollusks • Mollusks have a digestive system with two openings. • Some mollusks have an open circulatory system, which means they do not have vessels to contain their blood. • Others have a closed circulatory system, in which blood is carried through blood vessels instead of surrounding the organs.

26. Invertebrate Animals 2 Segmented Worms • Earthworms, leeches, and marine worms are segmented worms, or annelids. • Each segment has nerve cells, blood vessels, part of the digestive tract, and the coelom. • The coelom, or internal body cavity, separates the internal organs from the body wall. • Annelids have a closed circulatory system and a complete digestive system with two body openings.

27. Invertebrate Animals 2 Arthropods—Structure and Function • Arthropods are animals that have jointed appendages. • Appendages are structures such as claws, legs, and antennae that grow from the body.

28. Invertebrate Animals 2 Arthropods—Structure and Function • Arthropods have a rigid body covering called an exoskeleton. • They have an open circulatory system, and oxygen is brought directly to the tissues through spiracles.

29. Invertebrate Animals 2 Metamorphosis • Many arthropods completely change their body form as they mature. This change in body form is called metamorphosis. • Complete Metamorphosis has four stages—egg, larva, pupa, and adult.

30. Invertebrate Animals 2 Metamorphosis • Incomplete metamorphosis has only three stages—egg, nymph, and adult. A nymph looks similar to its parents, only smaller.

31. Invertebrate Animals 2 Echinoderms • Sea stars belong to a varied group of animals called echinoderms. • Echinoderms have spines of various lengths that cover the outside of their bodies. • All echinoderms have a water-vascular system.

32. Section Check 2 Question 1 How do cnidarians use nematocysts? Answer Nematocysts, or stinging cells, are used to capture prey. GLE 0707.1.2

33. Section Check 2 Question 2 This diagram of a sponge shows that sponges _______. SPI 0707.4.1 GLE 0707.Inq.2

34. Section Check 2 A. are hermaphrodites B. produce buds C. reproduce asexually D. use spicules for production SPI 0707.4.1 GLE 0707.Inq.2

35. Section Check 2 Answer The correct answer is A. Most sponges that reproduce sexually are hermaphrodites. Both sperm and eggs are produced from the same sponge. SPI 0707.4.1 GLE 0707.Inq.2

36. Section Check 2 Question 3 Which of the following describes the body of a roundworm? A. a medusa B. a polyp C. a tube within a tube D. has two cell layers GLE 0707.1.2

37. Section Check 2 Answer The correct answer is C. The two tubes are separated by a fluid-filled cavity. The inner tube is the digestive tract. GLE 0707.1.2

38. Vertebrate Animals 3 What is a chordate? • Three characteristics of all chordates are a notochord, a nerve cord, and pharyngeal pouches at some time during their development. • The notochord is a flexible rod that extends along the length of the developing organism.

39. Vertebrate Animals 3 What is a chordate? • Pharyngeal pouches are slitlike openings between the body cavity and the outside of the body. • They are present only during the early stages of the organism’s development.

40. Vertebrate Animals 3 Vertebrates • Vertebrates have an internal system of bones called an endoskeleton. • The vertebrae, skull, and other bones of the endoskeleton support and protect internal organs.

41. Vertebrate Animals 3 Body Temperature • Most vertebrate body temperatures change as the surrounding temperature changes. These animals are ectotherms or cold-blooded animals. • Humans and many other vertebrates are endotherms or warm-blooded animals. Their body temperature doesn’t change with the surrounding temperature.

42. Vertebrate Animals 3 Fish • There are three classes of fish: jawless, jawed cartilaginous, and bony. Fish are ectotherms that can be found in warm desert pools and the subfreezing Artic Ocean.

43. Vertebrate Animals 3 Fish • Fish have fleshy filaments called gills where carbon dioxide and oxygen are exchanged.

44. Vertebrate Animals 3 Fish • Most fish have pairs of fanlike fins. The top and the bottom fins stabilize the fish. Those on the sides steer and move the fish. • Most fish have scales. • Scales are thin structures made of a bony material that overlap like shingles on a house to cover the skin.

45. Vertebrate Animals 3 Amphibians • Amphibians are animals that spend part of their lives in water and part on land. • Frogs, toads, newts, and salamanders are examples of amphibians.

46. Vertebrate Animals 3 Amphibian Characteristics • Amphibians are vertebrates with a strong endoskeleton made of bones. • Adult amphibians use lungs instead of gills to exchange oxygen and carbon dioxide.

47. Vertebrate Animals 3 Amphibian Characteristics • Because amphibians have three-chambered hearts, the blood carrying oxygen mixes with the blood carrying carbon dioxide. • Adult amphibians also exchange oxygen and carbon dioxide through their skin, which increases their oxygen supply.

48. Vertebrate Animals 3 Reptiles • Reptiles are ectothermic vertebrates with dry, scaly skin. • Because reptiles do not depend on water for reproduction, most are able to live their entire lives on land.

49. Vertebrate Animals 3 Reptile Adaptations • All reptiles have lungs for exchanging oxygen and carbon dioxide. • Reptiles also have a neck that allows them to scan the horizon.

50. Vertebrate Animals 3 Reptile Adaptations • Two adaptations enable reptiles to reproduce successfully on land—internal fertilization and laying shell-covered, amniotic eggs. • The embryo develops with the moist protective environment of the amniotic egg. • When eggs hatch, young reptiles are fully developed.