Table of Contents – pages iii Unit 1:What is Biology? Unit 2:Ecology Unit 3:The Life of a Cell Unit 4:Genetics Unit 5:Change Through Time Unit 6:Viruses, Bacteria, Protists, and Fungi Unit 7:Plants Unit 8:Invertebrates Unit 9:Vertebrates Unit 10:The Human Body
Table of Contents – pages vii-xiii Unit 1: What is Biology? Chapter 1:Biology: The Study of Life Unit 2: Ecology Chapter 2:Principles of Ecology Chapter 3:Communities and Biomes Chapter 4:Population Biology Chapter 5:Biological Diversity and Conservation Unit 3:The Life of a Cell Chapter 6:The Chemistry of Life Chapter 7:A View of the Cell Chapter 8:Cellular Transport and the Cell Cycle Chapter 9:Energy in a Cell
Unit 4: Genetics Chapter 10:Mendel and Meiosis Chapter 11:DNA and Genes Chapter 12:Patterns of Heredity and Human Genetics Chapter 13:Genetic Technology Unit 5: Change Through Time Chapter 14:The History of Life Chapter 15:The Theory of Evolution Chapter 16:Primate Evolution Chapter 17:Organizing Life’s Diversity Table of Contents – pages vii-xiii
Unit 6: Viruses, Bacteria, Protists, and Fungi Chapter 18:Viruses and Bacteria Chapter 19:Protists Chapter 20:Fungi Unit 7: Plants Chapter 21:What Is a Plant? Chapter 22:The Diversity of Plants Chapter 23:Plant Structure and Function Chapter 24:Reproduction in Plants Table of Contents – pages vii-xiii
Table of Contents – pages vii-xiii Unit 8: Invertebrates Chapter 25:What Is an Animal? Chapter 26:Sponges, Cnidarians, Flatworms, and Roundworms Chapter 27:Mollusks and Segmented Worms Chapter 28:Arthropods Chapter 29:Echinoderms and Invertebrate Chordates
Table of Contents – pages vii-xiii Unit 9: Vertebrates Chapter 30:Fishes and Amphibians Chapter 31:Reptiles and Birds Chapter 32:Mammals Chapter 33:Animal Behavior Unit 10: The Human Body Chapter 34:Protection, Support, and Locomotion Chapter 35:The Digestive and Endocrine Systems Chapter 36:The Nervous System Chapter 37:Respiration, Circulation, and Excretion Chapter 38:Reproduction and Development Chapter 39:Immunity from Disease
Sponges, Cnidarians, Flatworms, and Roundworms Unit Overview – pages 670-671 What Is an Animal? Sponges, Cnidarians, Flatworms, and Roundworms Mollusks and Segmented Worms Arthropods Echinoderms and Invertebrate Chordates
Chapter Contents – page xi Chapter 26Sponges, Cnidarians, Flatworms, and Roundworms 26.1:Sponges 26.1:Section Check 26.2:Cnidarians 26.2:Section Check 26.3:Flatworms 26.3:Section Check 26.4:Roundworms 26.4:Section Check Chapter 26Summary Chapter 26Assessment
Chapter Intro-page 692 What You’ll Learn You will identify and compare and contrast the characteristics of sponges, cnidarians, flatworms, and roundworms. You will describe and evaluate the significance of sponge, cnidarian, flatworm, and roundworm adaptations.
26.1 Section Objectives – page 693 Section Objectives: • Relate the sessile life of sponges to their food-gathering adaptations. • Describe the reproductive adaptations of sponges.
Section 26.1 Summary – pages 693-697 What is a sponge? • Sponges are asymmetrical aquatic animals that have a variety of colors, shapes, and sizes. • Many are bright shades of red, orange, yellow, and green.
Section 26.1 Summary – pages 693-697 What is a sponge? • Although sponges do not resemble more familiar animals, they carry on the same life processes as all animals.
Section 26.1 Summary – pages 693-697 Sponges are pore-bearers • Sponges are classified in the invertebrate phylum Porifera, which means “pore bearer.” • Most live in marine biomes, but about 150 species can be found in freshwater environments.
Section 26.1 Summary – pages 693-697 Sponges are pore-bearers Water out • Sponges are mainly sessile organisms. Central cavity • Because most adult sponges can’t travel in search of food, they get their food by a process called filter feeding. Water in
Section 26.1 Summary – pages 693-697 Sponges are pore-bearers Water out • Filter feeding is a method in which an organism feeds by filtering small particles of food from water that pass by or through some part of the organism. Central cavity Water in
Section 26.1 Summary – pages 693-697 Cell organization in sponges • For some sponge species, if you took a living sponge and put it through a sieve, not only would the sponge’s cells be alive and separated out, but these cells would come together to form new sponges. • It can take several weeks for the sponge’s cells to reorganize themselves.
Section 26.1 Summary – pages 693-697 Cell organization in sponges • Many biologists hypothesize that sponges evolved directly from colonial, flagellated protists, such as Volvox. Volvox
Section 26.1 Summary – pages 693-697 Cell organization in sponges • More importantly, sponges exhibit a major step in the evolution of animals—the change from unicellular life to a division of labor among groups of organized cells.
Section 26.1 Summary – pages 693-697 Reproduction in sponges • Sponges can reproduce asexually and sexually. • Depending on the species, asexual reproduction can be by budding, fragmentation, or the formation of gemmules.
Section 26.1 Summary – pages 693-697 Reproduction in sponges • An external growth, called a bud, can form on a sponge. • If a bud drops off, it can float away, settle, and grow into a sponge. • Sometimes, buds do not break off. When this occurs, a colony of sponges forms. • Often, fragments of a sponge break off and grow into new sponges.
Section 26.1 Summary – pages 693-697 Reproduction in sponges • Some freshwater sponges produce seedlike particles, called gemmules, in the fall when waters cool. • The adult sponges die over the winter, but the gemmules survive and grow into new sponges in the spring when waters warm.
Section 26.1 Summary – pages 693-697 Reproduction in sponges • Most sponges reproduce sexually. • Some sponges have separate sexes, but most sponges are hermaphrodites. A hermaphrodite (hur MAF ruh dite) is an animal that can produce both eggs and sperm.
Section 26.1 Summary – pages 693-697 Reproduction in sponges • Eggs and sperm form from amoebocytes. • During reproduction, sperm released from one sponge can be carried by water currents to another sponge, where fertilization can occur.
Section 26.1 Summary – pages 693-697 Reproduction in sponges • Fertilization in sponges may be either external or internal. • A few sponges have external fertilization—fertilization that occurs outside the animal’s body. • Most sponges have internal fertilization, in which eggs inside the animal’s body are fertilized by sperm carried into the sponge with water.
Section 26.1 Summary – pages 693-697 Egg cell Sperm cells Flagella Larvae New sponge
Section 26.1 Summary – pages 693-697 Reproduction in sponges • In sponges, the collar cells collect and transfer sperm to amoebocytes. • The amoebocytes then transport the sperm to ripe eggs.
Section 26.1 Summary – pages 693-697 Support and defense systems in sponges • Sponges are soft-bodied invertebrates, that can be found at depths of about 8500 m. • Their internal structure gives them support and can help protect them from predators.
Section 26.1 Summary – pages 693-697 Support and defense systems in sponges • Some sponges have sharp, hard spicules located between the cell layers. • Spicules may be made of glasslike material or of calcium carbonate. Spicules
Section 26.1 Summary – pages 693-697 Support and defense systems in sponges • Other sponges have an internal framework made of silica or of spongin, a fibrous protein-like material. • Sponges can be classified according to the shape and makeup of their spicules and/or frameworks.
Section 26.1 Summary – pages 693-697 Support and defense systems in sponges • Besides sharp spicules, some sponges may have other methods of defense. • Some sponges contain chemicals that are toxic to fishes and to other predators.
Section 1 Check Question 1 What is the major evolutionary step in animals that sponges exhibit?
Section 1 Check Sponges are the first animals to exhibit the change from a unicellular life to a division of labor among groups of organized cells.
Section 1 Check Question 2 In sponges, where do fertilized eggs develop into zygotes? A. in the sponge’s osculum B. in the pore cells C. in the collar cells D. in the jelly between the cell layers
Section 1 Check The answer is D, in the jelly between the cell layers.
Section 1 Check Question 3 How many layers of cells make up a sponge? A. two B. three C. four D. five The answer is A, two.
26.2 Section Objectives – page 698 Section Objectives • Analyze the relationships among the classes of cnidarians. • Sequence the stages in the life cycle of a cnidarian. • Evaluate the adaptations of cnidarians for obtaining food.
Section 26.2 Summary – pages 698-705 What is a cnidarian? • Cnidarians (ni DARE ee uns) are a group of invertebrates made up of more than 9000 species of jellyfishes, corals, sea anemones, and hydras. • They can be found worldwide, and all but a few cnidarians live in marine biomes.
Section 26.2 Summary – pages 698-705 Body structure Mouth Tentacle • A cnidarian’s body is radially symmetrical. It has one body opening and is made up of two layers of cells. Cavity Inner cell layer Jellylike layer Bud Outer cell layer Disc
Section 26.2 Summary – pages 698-705 Body structure Mouth • The two cell layers are organized into tissues with specific functions. Tentacle Cavity Inner cell layer • The inner layer is adapted mainly to assist in digestion. Jellylike layer Bud Outer cell layer Disc
Section 26.2 Summary – pages 698-705 Body structure • Because a cnidarian’s body is only two layers of cells, no cell is ever far from water. • Oxygen dissolved in water can diffuse directly into body cells. • Carbon dioxide and other wastes can move out of a cnidarian’s body cells directly into the surrounding water.
Section 26.2 Summary – pages 698-705 A Cnidarian • Cnidarians display a remarkable variety of colors, shapes and sizes. Some can be as small as the tip of a pencil. • Most cnidarians have two distinct body forms during their life cycles. • A polyp is the sessile form of a cnidarian. Its mouth is surrounded by tentacles. • Examples of polyps include sea anemones, corals, and hydras.
Section 26.2 Summary – pages 698-705 Body form • Most cnidarians undergo a change in body form during their life cycles. Polyp Medusa
Section 26.2 Summary – pages 698-705 Body form • There are two body forms, the polyp and the medusa. Polyp Medusa
Section 26.2 Summary – pages 698-705 Body form • In cnidarians, one body form may be more observable than the other. In jellyfishes, the medusa is the body form usually observed. • The polyp is the familiar body form of hydras.
Section 26.2 Summary – pages 698-705 Reproduction in cnidarians • All cnidarians have the ability to reproduce sexually and asexually. • Sexual reproduction occurs in only one phase of the life cycle. • It usually occurs in the medusa stage, unless there is no medusa stage then the polyp can reproduce sexually.
Section 26.2 Summary – pages 698-705 Digestion in cnidarians • Cnidarians are predators that capture or poison their prey using nematocysts. • A nematocyst (nih MA tuh sihst) is a capsule that contains a coiled, threadlike tube. • The tube may be sticky or barbed, and it may contain toxic substances. • Nematocysts are located in stinging cells that are on tentacles.