Table of Contents – pages iv-v 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: InvertebratesInvertebrates Unit 9: Vertebrates Unit 10: The Human Body

Table of Contents – pages iv-v 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

Table of Contents – pages iv-v 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 iv-v 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 iv-v Unit 8: InvertebratesInvertebrates 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 ChordatesEchinoderms and Invertebrate Chordates

Table of Contents – pages iv-v 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

Unit Overview – pages Invertebrates What is an animal? Sponges, Cnidarians, Flatworms and Roundworms Mollusks and Segmented Worms Arthropods Echinoderms and Invertebrate Chordates

Chapter Contents – page xi Chapter 29 Echinoderms and Invertebrate ChordatesEchinoderms and Invertebrate Chordates 29.1: EchinodermsEchinoderms 29.1: Section CheckSection Check 29.2: Invertebrate ChordatesInvertebrate Chordates 29.2: Section CheckSection Check Chapter 29 SummarySummary Chapter 29 AssessmentAssessment

Chapter Intro-page 762 What You’ll Learn You will compare and contrast the adaptations of echinoderms. You will distinguish the features of chordates by examining invertebrate chordates.

29.1 Section Objectives – page 763 Compare similarities and differences among the classes of echinoderms. Section Objectives: Interpret the evidence biologists have for determining that echinoderms are close relatives of chordates.

Section 29.1 Summary – pages Echinoderms move by means of hundreds of hydraulic, suction-cup-tipped appendages and have skin covered with tiny, jawlike pincers. Echinoderms are found in all the oceans of the world. What is an echinoderm?

Section 29.1 Summary – pages If you were to examine the skin of several different echinoderms, you would find that they all have a hard, spiny, or bumpy endoskeleton covered by a thin epidermis. Echinoderms have endoskeletons

Section 29.1 Summary – pages Sea stars, sometimes called starfishes, may not appear spiny at first glance, but a close look reveals that their long, tapering arms, called rays, are covered with short, rounded spines. Echinoderms have endoskeletons The endoskeleton of all echinoderms is made primarily of calcium carbonate, the compound that makes up limestone.

Section 29.1 Summary – pages Some of the spines found on sea stars and sea urchins have become modified into pincerlike appendages called pedicellariae Echinoderms have endoskeletons

Section 29.1 Summary – pages Echinoderms have endoskeletons An echinoderm uses its jawlike pedicellariae for protection and for cleaning the surface of its body. Pedicellariae

Section 29.1 Summary – pages Echinoderms have radial symmetry You may remember that radial symmetry is an advantage to animals that are stationary or move slowly. Radial symmetry enables these animals to sense potential food, predators, and other aspects of their environment from all directions.

Section 29.1 Summary – pages The water vascular system The water vascular system is a hydraulic system that operates under water pressure. Water enters and leaves the water vascular system of a sea star through the madreporite, a sievelike, disk-shaped opening on the upper surface of the echinoderm’s body.

Section 29.1 Summary – pages The water vascular system The underside of a sea star has tube feet that run along a groove on the underside of each ray.

Section 29.1 Summary – pages The water vascular system Tube feet are hollow, thin-walled tubes that end in a suction cup. Tube feet look somewhat like miniature droppers. The round, muscular structure called the ampulla works something like the bulb of a dropper.

Section 29.1 Summary – pages The water vascular system Each tube foot works independently of the others, and the animal moves along slowly by alternately pushing out and pulling in its tube feet. Ampullae

Section 29.1 Summary – pages The water vascular system Tube feet also function in gas exchange and excretion. Gases are exchanged and wastes are eliminated by diffusion through the thin walls of the tube feet.

Section 29.1 Summary – pages Echinoderms have varied nutrition All echinoderms have a mouth, stomach, and intestines, but their methods of obtaining food vary. Sea stars are carnivorous and prey on worms or on mollusks such as clams.

Section 29.1 Summary – pages Echinoderms have varied nutrition Most sea urchins are herbivores and graze on algae. Brittle stars, sea lilies, and sea cucumbers feed on dead and decaying matter that drifts down to the ocean floor.

Section 29.1 Summary – pages Echinoderms have a simple nervous system Echinoderms have no head or brain, but they do have a central nerve ring that surrounds the mouth. Ring canal

Section 29.1 Summary – pages Echinoderms have a simple nervous system Nerves extend from the nerve ring down each ray. Each radial nerve then branches into a nerve net that provides sensory information to the animal. Echinoderms have cells that detect light and touch, but most do not have sensory organs.

Section 29.1 Summary – pages Echinoderms have a simple nervous system Sea stars are an exception. A sea star’s body consists of long, tapering rays that extend from the animal’s central disk. A sensory organ known as an eyespot and consisting of a cluster of light-detecting cells is located at the tip of each arm, on the underside.

Section 29.1 Summary – pages Echinoderms have a simple nervous system Eyespots enable sea stars to detect the intensity of light. Sea stars also have chemical receptors on their tube feet.

Section 29.1 Summary – pages Echinoderms have bilaterally symmetrical larvae If you examine the larval stages of echinoderms, you will find that they have bilateral symmetry. Through metamorphosis, the free-swimming larvae make dramatic changes in both body parts and in symmetry.

Starfish Larva

Section 29.1 Summary – pages Echinoderms are deuterostomes Echinoderms are deuterostomes. This pattern of development indicates a close relationship to chordates, which are also deuterostomes.

Section 29.1 Summary – pages Approximately 6000 species of echinoderms exist today. About one-fourth of these species are in the class Asteroidea, to which the sea stars belong. Diversity of Echinoderms

Section 29.1 Summary – pages Diversity of Echinoderms The five other classes of living echinodems are Ophiuroidea, the brittle stars; Echinoidea, the sea urchins and sand dollars.

Section 29.1 Summary – pages Holothuroidea, the sea cucumbers; Crinoidea, the sea lilies and feather stars; and Concentricycloidea, the sea daisies. Sea Cucumber Diversity of Echinoderms

Section 29.1 Summary – pages Sea stars Most species of sea stars have five rays, but some have more. Some species may have more than 40 rays.

Section 29.1 Summary – pages

Sunflower Starfish Chasing Prey

Section 29.1 Summary – pages Brittle stars Brittle stars are extremely fragile. This adaptation helps the brittle star survive an attack by a predator. While the predator is busy with the broken off ray, the brittle star can escape. A new ray will regenerate.

Section 29.1 Summary – pages Brittle stars Brittle stars propel themselves with the snake like, slithering motion of their flexible rays. They use their tube feet to pass particles of food along the rays and into the mouth in the central disk. Feeding Video

Section 29.1 Summary – pages Sea urchins and sand dollars Sea urchins and sand dollars are globe or disk-shaped animals covered with spines; they do not have rays. A living sand dollar is covered with minute, hair-like spines that are lost when the animal dies. A sand dollar has tube feet that protrude from the petal-like markings on its upper surface.

Section 29.1 Summary – pages Sea urchins and sand dollars These tube feet are modified into gills and are used for respiration. Tube feet on the animal’s bottom surface aid in bringing food particles to the mouth. Video

Section 29.1 Summary – pages Sea urchins and sand dollars Sea urchins look like living pincushions, bristling with long, usually pointed spines. Sea urchins have long, slender tube feet that, along with the spines, aid the animal in locomotion. Video

Section 29.1 Summary – pages Sea cucumbers Sea cucumbers are so called because of their vegetable-like appearance. Their leathery covering allows them flexibility as they move along the ocean floor.

Section 29.1 Summary – pages Sea cucumbers When sea cucumbers are threatened, they may expel a tangled, sticky mass of tubes through the anus, or they may rupture, releasing some internal organs that are regenerated in a few weeks. Sea cucumbers reproduce by shedding eggs and sperm into the water, where fertilization occurs. Video Video 2VideoVideo 2

Section 29.1 Summary – pages Sea lilies and feather stars Sea lilies and feather stars resemble plants in some ways. Sea lilies are the only sessile echinoderms. Feather stars are sessile only in larval form. The adult feather star uses its feathery arms to swim from place to place. Video

Section 29.1 Summary – pages Sea daisies Sea daisies are flat, disk-shaped animals less than 1 cm in diameter. Their tube feet are located around the edge of the disk rather than along radial lines, as in other echinoderms.

Sea Daisy

Section 29.1 Summary – pages Origins of Echinoderms The earliest echinoderms may have been bilaterally symmetrical as adults, and probably were attached to the ocean floor by stalks. Another view of the earliest echinoderms is that they were bilateral and free swimming.

Section 29.1 Summary – pages Origins of Echinoderms The echinoderms represent the only major group of deuterostome invertebrates. This pattern of development is one piece of evidence biologists have for placing echinoderms as the closest invertebrate relatives of the chordates.

Section 29.1 Summary – pages Origins of Echinoderms Most echinoderms have been found as fossils from the early Paleozoic Era. Fossils of brittle stars are found beginning at a later period. Not much is known about the origin of sea daisies.

Section 1 Check Question 1 Why is radial symmetry an advantage to animals that are stationary or slow moving?

Section 1 Check Radial symmetry enables stationary or slow moving animals to sense potential food, predators, and other aspects of their environment from all directions.

Section 1 Check Question 2 What is the similarity between the endoskeleton of echinoderms and the exoskeleton of crustaceans? Both of these features are composed of calcium carbonate. Answer

Section 1 Check Question 3 Pincerlike appendages from modified spines on sea stars are called _______. A. rays B. pedicellariae C. madreporites D. tube feet

Pedicellariae Section 1 Check The answer is B, pedicellariae.

Section 1 Check Question 4 Which of the following terms does NOT describe an echinoderm’s method of obtaining food? A. carnivore B. herbivore C. parasite D. scavenger The answer is C, parasite.

Section 1 Check Question 5 What stimulates a sea star to move in a given direction?

Section 1 Check Sea stars move toward light and toward chemical signals emitted from potential prey animals.

29.2 Section Objectives – page 770 Summarize the characteristics of chordates. Section Objectives: Explain how invertebrate chordates are related to vertebrates. Distinguish between sea squirts and lancelets.

Section 29.2 Summary – pages What is an invertebrate chordate? The phylum Chordata includes three subphyla: Urochordata, the tunicates (sea squirts); Cephalochordata, the lancelets; and Vertebrata, the vertebrates. Invertebrate chordates have a notochord, a dorsal hollow nerve cord, pharyngeal pouches, and a postanal tail at some time during their development.

Section 29.2 Summary – pages What is an invertebrate chordate? In addition, all chordates have bilateral symmetry, a well-developed coelom, and segmentation. Postanal tail Anus Muscle blocks Pharyngeal pouches Mouth Dorsal hollow nerve cord Notochord

Section 29.2 Summary – pages All chordates have a notochord The embryos of all chordates have a notochord (NOH tuh kord) — a long, semirigid, rod-like structure located between the digestive system and the dorsal hollow nerve cord. Gill slits Nerve cord Notochord

Section 29.2 Summary – pages In invertebrate chordates, the notochord may be retained into adulthood. But in vertebrate chordates, this structure is replaced by a backbone. Invertebrate chordates do not develop a backbone. All chordates have a notochord

Section 29.2 Summary – pages

All chordates have pharyngeal pouches The pharyngeal pouches of a chordate embryo are paired openings located in the pharynx, behind the mouth. In aquatic chordates, pharyngeal pouches develop openings called gill slits. In terrestrial chordates, pharyngeal pouches develop into other structures.

Section 29.2 Summary – pages At some point in development, all chordates have a postanal tail. Humans are chordates, and during the early development of the human embryo, there is a postanal tail that disappears as development continues. Postanal tail All chordates have a postanal tail

Section 29.2 Summary – pages All chordates have a postanal tail In most animals that have tails, the digestive system extends to the tip of the tail, where the anus is located. Chordates, however, usually have a tail that extends beyond the anus.

Section 29.2 Summary – pages Muscle blocks aid in movement of the tail. Muscle blocks are modified body segments that consist of stacked muscle layers. Muscle blocks are anchored by the notochord, which gives the muscles a firm structure to pull against. All chordates have a postanal tail

Section 29.2 Summary – pages Homeotic genes control development Homeotic genes specify body organization and direct the development of tissues and organs in an embryo. Studies of chordate homeotic genes have helped scientists understand the process of development and the relationship of invertebrate chordates to vertebrate chordates.

Section 29.2 Summary – pages Diversity of Invertebrate Chordates The invertebrate chordates belong to two subphyla of the phylum chordata: subphylum Urochordata, the tunicates (TEW nuh kaytz), also called sea squirts, and subphylum Cephalochordata, the lancelets.

Section 29.2 Summary – pages Tunicates are sea squirts Although adult tunicates do not appear to have any shared chordate features, the larval stage, has a tail that makes it look similar to a tadpole.

Section 29.2 Summary – pages Tunicates are sea squirts Tunicate larvae do not feed and are free swimming after hatching. They soon settle and attach themselves with a sucker to boats, rocks, and the ocean bottom. Many adult tunicates secrete a tunic, a tough sac made of cellulose, around their bodies.

Section 29.2 Summary – pages Tunicates are sea squirts Colonies of tunicates sometimes secrete just one big tunic that has a common opening to the outside. Only the gill slits in adult tunicates indicate their chordate relationship. Adult tunicates are small, tubular animals that range in size from microscopic to several centi-meters long.

Section 29.2 Summary – pages Tunicates are sea squirts If you remove a tunicate from its sea home, it might squirt out a jet of water-hence the name sea squirt.

Section 29.2 Summary – pages

Lancelets are similar to fishes Lancelets are small, streamlined, and common marine animals, usually about 5 cm long. Like tunicates, lancelets are filter feeders.

Section 29.2 Summary – pages Lancelets are similar to fishes Unlike tunicates, however, lancelets retain all their chordate features throughout life. Postanal tail Anus Muscle blocks Intestine Notochord Dorsal hollow nerve cord Oral hood with tentacles Mouth Gill slits in pharynx

Section 29.2 Summary – pages Lancelets are similar to fishes Although lancelets look somewhat similar to fishes, they have only one layer of skin, with no pigment and no scales.

Section 29.2 Summary – pages Lancelets are similar to fishes Lancelets do not have a distinct head, but they do have light sensitive cells on the anterior end. They also have a hood that covers the mouth and the sensory tentacles surrounding it. The tentacles direct the water current and food particles toward the animal’s mouth.

Section 29.2 Summary – pages Origins of Invertebrate Chordates Biologist are not sure where sea squirts and lancelets fit in the phylogeny of chordates. According to one hypothesis, echinoderms, invertebrate chordates, and vertebrates all arose from ancestral sessile animals that fed by capturing food in tentacles.

Section 29.2 Summary – pages Origins of Invertebrate Chordates Recent discoveries of fossil forms of organisms that are similar to living lancelets in rocks 550 million years old show that invertebrate chordates probably existed before vertebrate chordates.

Section 2 Check Which of the following features is NOT shared by all chordates? Question 1 D. protostome development C. segmentation B. coelom A. bilateral symmetry The answer is D, protostome development.

Section 2 Check In vertebrates the notochord is replaced by the _______. Question 2 D. medulla C. spinal chord B. brain A. backbone The answer is A, backbone.

Section 2 Check How does a notochord aid in the movement of a chordate? Question 3

Section 2 Check The notochord anchors internal muscles and enables invertebrate chordates to make rapid movements of the body, which they use to propel themselves. Postanal tail Anus Muscle blocks Pharyngeal pouches Mouth Dorsal hollow nerve cord Notochord

Section 2 Check How is a tunicate heart unusual? Question 4

Section 2 Check The tunicate heart pumps blood in one direction for several minutes and then reverses direction. Heart

Section 2 Check What is the only feature of adult tunicates that indicates their chordate relationship? Question 5 D. dorsal hollow nerve cord C. postanal tail B. gill slits A. notochord

Section 2 Check The answer is B, gill slits. Gill slits

Chapter Summary – 29.1 Echinoderms have spines or bumps on their endoskeletons, radial symmetry, and water vascular systems. Most move by means of the suction action of tube feet. Echinoderms Echinoderms can be carnivorous, herbivorous, scavengers, or filter feeders. Echinoderms include sea stars, brittle stars, sea urchins, sand dollars, sea cucumbers, sea lilies, feather stars, and sea daisies.

Chapter Summary – 29.1 Deuterostome development is an indicator of the close phylogenetic relationship between echinoderms and chordates. Echinoderms A good fossil record of this phylum exists because the endoskeleton of echinoderms fossilizes easily.

Chapter Summary – 29.2 All chordates have a dorsal hollow nerve cord, a notochord, pharyngeal pouches, and a postanal tail at some stage during development. Invertebrate Chordates All chordates also have bilateral symmetry, a well-developed coelem, and segmentation.

Chapter Summary – 29.2 Sea squirts and lancelets are invertebrate chordates. Invertebrate Chordates Vertebrate chordates may have evolved from larval stages of ancestral invertebrate chordates.

Chapter Assessment Question 1 Which of the following is not a function of tube feet? D. movement C. gas exchange B. excretion A. digestion

Chapter Assessment The answer is A, digestion. Tube feet

Chapter Assessment Question 2 What is the difference in the way sea stars and brittle stars use their tube feet?

Chapter Assessment Sea stars use their tube feet to move. Brittle stars use their feet to pass particles of food along their rays and into their mouth.

Chapter Assessment Question 3 The only sessile echinoderms belong to the _______. D. Crinoidea C. Echinoidea B. Ophiuroidea A. Asteroidea

Chapter Assessment The answer is D. The Crinoidea include the sea lilies which are sessile.

Chapter Assessment Question 4 Describe the sea cucumber’s method of protection from predators.

Chapter Assessment When sea cucumbers are threatened they may expel portions of themselves through the anus or a ruptured part of the skin to confuse predators. The expelled portions are regenerated later.

Chapter Assessment Question 5 What is the adaptive value of colonies of sea cucumbers all shedding eggs and sperm into the water at the same time? Answer The adaptive value of this behavior is that the fertilization of many eggs is assured.

Chapter Assessment Question 6 Endoskeleton Madreporite Tube feet Pedicellariae Anus Stomach Digestive gland Eyespots Ray Nerve ring Mouth Reproductive organ Endoskeletal plates Radial nerve Ampullae Radial canal Ring canal

Chapter Assessment The sea star displays radial symmetry because each ray is a duplicate of the others and all organs extend around a central point in a radial or circular arrangement.

Chapter Assessment Question 7 Why is the fossil record of invertebrate chordates incomplete? Answer Sea squirts and lancelets have no bones, shell, or other hard parts that could form fossils.

Chapter Assessment Question 8 Where is a tunicate’s postanal tail? Answer A tunicate possesses a postanal tail only in its larval stage.

Chapter Assessment Question 9 Lancelets and tunicates are both _______. D. decomposers C. parasites B. filter feeders A. predators The answer is B, filter feeders.

Chapter Assessment Question 10 The tunic of Urochordates is composed of _______. D. cellulose C. calcium carbonate B. chitin A. mesoderm The answer is D, cellulose.

Photo Credits General Biological Inc. Ward's Natural Science Establishment, Inc. Digital Stock Ed Shay American Petrolium Inst. Harris Biological Supply LTD Susan Marquart Carolina Biological Supply Co. PhotoDisc Alton Biggs

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