Life Science Chapter 14


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Presentatiion to assist with teaching about mollusks, arthropods, spiders, earthworms, echinoderms. slugs and more.
This is not my own creation, but I really liked it. I added several videos which probably will not show up through slide share. The videos were my own addition.

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Life Science Chapter 14

  1. 2. Chapter: Mollusks, Worms, Arthropods, Echinoderms Table of Contents Section 3: Arthropods Section 1: Mollusks Section 2: Segmented Worms Section 4: Echinoderms
  2. 3. <ul><li>Mollusks (MAH lusks) are soft-bodied invertebrates with bilateral symmetry and usually one or two shells. </li></ul><ul><li>Their organs are in a fluid-filled cavity. </li></ul><ul><li>Most mollusks live in water, but some live on land. </li></ul>Characteristics of Mollusks Mollusks 1 <ul><li>Snails, clams, and squid are examples of mollusks. </li></ul>
  3. 5. Body Plan Mollusks 1 <ul><li>All mollusks have a thin layer of tissue called a mantle , which covers the body organs. </li></ul>These are located in the visceral (VIH suh rul) mass .
  4. 6. Body Plan Mollusks 1 <ul><li>Between the soft body and the mantle is a space called the mantle cavity. It contains gills —the </li></ul>organs that exchange carbon dioxide for oxygen.
  5. 7. <ul><li>The mantle also secretes the shell or protects the body if the mollusk does not have a shell. </li></ul><ul><li>The shell is made up of several layers. </li></ul><ul><li>The inside layer is the smoothest. It is usually the thickest layer because it’s added to throughout the life of the mollusk. </li></ul>Body Plan Mollusks 1 <ul><li>The inside layer also protects the soft body. </li></ul>
  6. 8. <ul><li>Most mollusks have an open circulatory system in which the heart moves blood out into the open spaces around the body organs. </li></ul><ul><li>The blood, completely surrounds and nourishes the body organs. </li></ul>Body Plan Mollusks 1
  7. 9. Body Plan Mollusks 1 <ul><li>Most mollusks have a well-developed head with a mouth and some sensory organs. </li></ul><ul><li>Some mollusks have tentacles. </li></ul><ul><li>On the underside of a mollusk is the muscular foot, which is used for movement. </li></ul>
  8. 11. Classification of Mollusks Mollusks 1 <ul><li>Mollusks that have shells are then classified by the kind of shell and kind of foot that they have. </li></ul><ul><li>The three most common groups of mollusks are gastropods, bivalves, and cephalopods. </li></ul>
  9. 12. Gastropods Mollusks 1 <ul><li>The largest group of mollusks, the gastropods, includes snails, conchs, abalones, whelks, sea slugs, and garden slugs. </li></ul><ul><li>Gastropods use a radula (RA juh luh) —a tonguelike organ with rows of teeth —to obtain food. </li></ul>
  10. 13. Gastropods Mollusks 1 <ul><li>Slugs and many snails are adapted to life on land. </li></ul><ul><li>They move by rhythmic contractions of the muscular foot. </li></ul><ul><li>Glands in the foot secrete a layer of mucus on which they slide. </li></ul><ul><li>Slugs do not have shells but are protected by a layer of mucus instead, so they must live in moist places. </li></ul>
  11. 15. Bivalves Mollusks 1 <ul><li>Mollusks that have a hinged, two-part shell joined by strong muscles are called bivalves. </li></ul><ul><li>Clams, oysters, and scallops are bivalve mollusks. </li></ul>
  12. 16. Bivalves Mollusks 1 <ul><li>These animals pull their shells closed by contracting powerful muscles near the hinge. To open their shells, they relax these muscles. </li></ul>
  13. 17. Bivalves Mollusks 1 <ul><li>For protection, clams burrow deep into the sand by contracting and relaxing their muscular foot. </li></ul><ul><li>Mussels and oysters attach themselves with a strong thread or cement to a solid surface. This keeps waves and currents from washing them away. </li></ul>
  14. 18. Cephalopods Mollusks 1 <ul><li>The most specialized and complex mollusks are the cephalopods (SE fuh luh pawdz), which includes squid, octopuses, cuttlefish, and chambered nautiluses. </li></ul><ul><li>Cephalopods have a large, well-developed head. </li></ul>
  15. 19. Cephalopods Mollusks 1 <ul><li>Their foot is divided into many tentacles with strong suction cups or hooks for capturing prey. </li></ul><ul><li>All cephalopods are predators. They feed on fish, crustaceans, worms, and other mollusks. </li></ul>
  16. 21. Cephalopods Mollusks 1 <ul><li>Squid and octopuses have a well-developed nervous system and large eyes similar to human eyes. </li></ul><ul><li>Unlike other mollusks, cephalopods have a closed circulatory system , in which blood containing food and oxygen moves through the body in a series of closed vessels. </li></ul>
  17. 22. Cephalopod Propulsion Mollusks 1 <ul><li>Squid and other cephalopods have a water-filled cavity between an outer muscular covering and its internal organs . </li></ul><ul><li>When the cephalopod tightens its muscular covering, water is forced out through an opening neat the head. </li></ul><ul><li>According to Newton’s third law of motion, when one object exerts a force on a second object, the second object exerts a force on the first that is equal and opposite in direction. </li></ul>
  18. 23. Value of Mollusks Mollusks 1 <ul><li>Many people make their living raising or collecting mollusks to sell for food. </li></ul><ul><li>Many mollusk shells are used for jewelry and decoration. </li></ul><ul><li>Pearls are produced by several species of mollusks. </li></ul>
  19. 24. Value of Mollusks Mollusks 1 <ul><li>Even though mollusks are beneficial in many ways, they also can cause problems for humans. </li></ul><ul><li>Land slugs and snails damage plants. </li></ul><ul><li>Certain species of snails are hosts of parasites that infect humans. </li></ul><ul><li>Eating infected mollusks can result in sickness or even death. </li></ul>
  20. 25. 1 Section Check Question 1 Which structure is responsible for exchanging carbon dioxide from the mollusk for oxygen in the water?
  21. 26. 1 Section Check A. heart B. gills C. mantle D. radula
  22. 27. 1 Section Check Answer The answer is B. Gills are located in the mantle cavity.
  23. 28. 1 Section Check Question 2 Which structure is responsible for helping this organism move?
  24. 29. 1 Section Check A. foot B. mantle C. Mantle cavity D. radula
  25. 30. 1 Section Check Answer The answer is A. Slugs and snails move by rhythmic contractions of the muscular foot.
  26. 31. Section Check Question 3 A squid is what type of mollusk? A. bivalve B. cephalopod C. gastropod D. radula 1
  27. 32. Section Check Answer The answer is B. Cephalopods have large, well developed heads and their foot is divided into many tentacles. 1
  28. 33. Segmented Worm Characteristics <ul><li>Annelids (A nuh ludz) have tube-shaped bodies that are divided into many segments. </li></ul><ul><li>On the outside of each body segment are bristlelike structures called setae (SEE tee). </li></ul><ul><li>Segmented worms use their setae to hold on to the soil and to move. </li></ul>Segmented Worms 2
  29. 34. Segmented Worm Characteristics <ul><li>Segmented worms also have bilateral symmetry, a body cavity that holds the organs, and two body openings —a mouth and an anus. </li></ul><ul><li>Earthworms, marine worms, and leeches are examples of annelids. </li></ul>Segmented Worms 2
  30. 35. Earthworm Body Systems <ul><li>The most well-known annelids are earthworms. They have a definite anterior, or front end, and a posterior, or back end. </li></ul><ul><li>Earthworms have more than 100 body segments. The segments can be seen on the outside and the inside of the body cavity. </li></ul>Segmented Worms 2 <ul><li>Each body segment, except for the first and last segments, has four pairs of setae. </li></ul>
  31. 36. Digestion and Excretion <ul><li>As an earthworm burrows through the soil, it takes soil into its mouth. </li></ul><ul><li>The soil ingested by an earthworm moves to the crop , which is a sac used for storage. </li></ul>Segmented Worms 2 <ul><li>Behind the crop is a muscular structure called the gizzard , which grinds the soil and the bits of organic matter. </li></ul>
  32. 38. Digestion and Excretion <ul><li>This ground material passes to the intestine, where the organic matter is broken down and the nutrients are absorbed by the blood. </li></ul><ul><li>Wastes leave the worm through the anus. </li></ul>Segmented Worms 2 <ul><li>Their wastes pole up at the openings to their burrows. </li></ul><ul><li>These piles are called castings which help fertilize the soil. </li></ul>
  33. 39. Circulation and Respiration <ul><li>Earthworms have a closed circulatory system. </li></ul>Segmented Worms 2 <ul><li>Two blood vessels meet in the front end of the earthworm and </li></ul>connect to heart-like structures called aortic arches, which pump blood through the body.
  34. 40. Circulation and Respiration Segmented Worms 2 <ul><li>Oxygen and carbon dioxides are exchanged through their skin, which is covered with a thin film of </li></ul>watery mucus.
  35. 41. Nerve Response and Reproduction <ul><li>Earthworms have a small brain in their front segment. </li></ul><ul><li>Nerves in each segment join to form a main nerve cord that connects to the brain. </li></ul>Segmented Worms 2 <ul><li>Earthworms respond to light, temperature, and moisture. </li></ul>
  36. 42. Nerve Response and Reproduction <ul><li>Earthworms are hermaphrodites (hur MA fruh dites) —meaning they produce sperm and eggs in the same body. </li></ul><ul><li>Even though each worm has male and female reproductive structures, an individual worm can’t fertilize its own eggs. </li></ul>Segmented Worms 2 <ul><li>Instead, it has to receive sperm from another earthworm in order to reproduce. </li></ul>
  37. 43. Marine Worms <ul><li>More than 8,000 species of marine worms, or polychaetes, (PAH lee keets) exist. </li></ul><ul><li>Polchaetes, like earthworms, have segments with setae. However, the setae occur in bundles on these worms. </li></ul>Segmented Worms 2
  38. 44. Marine Worms <ul><li>Sessile, bottom-dwelling polychaetes, have specialized tentacles that are used for exchanging oxygen and carbon dioxide and gathering food. </li></ul><ul><li>Some marine worms build tubes around their bodies and retreat into their tubes when startled. </li></ul>Segmented Worms 2
  39. 45. Marine Worms <ul><li>Free-swimming polychaetes have a head with eyes, a tail, and parapodia (per uh POH dee uh). </li></ul><ul><li>Parapodia are paired, fleshy outgrowths which aid in feeding and locomotion. </li></ul>Segmented Worms 2
  40. 46. Leeches <ul><li>Leeches are segmented worms, but their bodies are not as round or as long as earthworms are, and they don’t have setae. </li></ul><ul><li>They feed on the blood of other animals. </li></ul>Segmented Worms 2 <ul><li>A sucker at each end of a leech’s body is used to attach itself to an animal. </li></ul>
  41. 47. Leeches <ul><li>Leeches produce many chemicals, including an anesthetic (a nus THEH tihk) that numbs the wound so you don’t feel its bite. </li></ul><ul><li>After the leech has attached itself, it cuts into the animal and sucks out two to ten times its own weight in blood. </li></ul>Segmented Worms 2
  42. 48. Leeches and Medicine <ul><li>Sometimes, leeches are used after surgery to keep blood flowing to the repaired area. </li></ul><ul><li>Besides the anti-clotting chemical, leech saliva also contains a chemical that dilates blood vessels, which improves the blood flow and allows the wound to heal more quickly. </li></ul>Segmented Worms 2
  43. 49. Value of Segmented Worms <ul><li>Earthworms help aerate the soil by constantly burrowing through it. </li></ul><ul><li>Earthworms speed up the return of nitrogen and other nutrients to the soil for use by plants. </li></ul>Segmented Worms 2 <ul><li>Researchers are developing drugs based on the chemicals that come from leeches because leech saliva prevents blood clots. </li></ul><ul><li>Marine worms and their larvae are food for many fish, invertebrates, and mammals. </li></ul>
  44. 50. Origin of Segmented Worms <ul><li>Some scientists hypothesize that segmented worms evolved in the sea. </li></ul><ul><li>The fossil record for segmented worms is limited because of their soft bodies. </li></ul>Segmented Worms 2 <ul><li>The tubes of marine worms are the most common fossils of the segmented worms. </li></ul><ul><li>Some of these fossils date back about 620 million years. </li></ul>
  45. 51. Origin of Segmented Worms <ul><li>Mollusks and segmented worms may have a common ancestor. </li></ul>Segmented Worms 2 <ul><li>Their larvae are similar and are the best evidence </li></ul>that they have a common ancestor.
  46. 52. 2 Section Check Question 1 Which letter corresponds with the setae? A. A B. B C. C D. D
  47. 53. 2 Section Check Answer The answer is A. Setae are the bristlelike structures segmented worms use to hold onto soil and to move.
  48. 54. 2 Section Check Question 2 Which letter corresponds with the structures that pump blood through the body? A. D B. E C. F D. G
  49. 55. 2 Section Check Answer The answer is D. Earthworms have five aortic arches that pump blood throughout their bodies.
  50. 56. 2 Section Check Question 3 How are leeches valuable medically? <ul><li>Chemicals in their saliva prevent blood </li></ul><ul><li>from clotting. </li></ul><ul><li>B. Leeches act as blood transfusers. </li></ul><ul><li>C. Leeches prevent pain from occurring in </li></ul><ul><li>major wounds. </li></ul><ul><li>D. Leeches filter and purify blood . </li></ul>
  51. 57. 2 Section Check Answer The answer is A. Leeches are sometimes used after surgery to keep blood flowing to the repaired area.
  52. 58. Characteristics of Arthropods <ul><li>There are more than a million different species of arthropods, (AR thruh pahdz). </li></ul><ul><li>The jointed appendages of arthropods can include legs, antennae, claws, and pincers. </li></ul>Arthropods 3 <ul><li>Arthropods also have bilateral symmetry, segmented bodies, an exoskeleton, a body cavity, a digestive system with two openings, and a nervous system. </li></ul>
  53. 59. Characteristics of Arthropods <ul><li>Most arthropods species have separate sexes and reproduce sexually. </li></ul><ul><li>Arthropods are adapted to living in almost every environment. </li></ul>Arthropods 3
  54. 61. Segmented Bodies <ul><li>The bodies of arthropods are divided into segments. </li></ul><ul><li>Some arthropods have many segments, but others have segments that are fused together to form body regions, such as those of insects, spiders, and crabs. </li></ul>Arthropods 3
  55. 62. Exoskeletons <ul><li>All arthropods have a hard, outer covering called an exoskeleton . </li></ul><ul><li>It covers, supports, and protects the internal body and provides places for muscles to attach. </li></ul>Arthropods 3 <ul><li>In many land-dwelling arthropods, such as insects, the exoskeleton has a waxy layer that reduces water loss from the animal. </li></ul>
  56. 63. Exoskeletons <ul><li>An exoskeleton cannot grow as the animal grows. </li></ul><ul><li>From time to time, the exoskeleton is shed and replaced by a new one in a process called molting . </li></ul>Arthropods 3 <ul><li>While the animals are molting, they are not well protected from predators because the new exoskeleton is soft. </li></ul>
  57. 64. Insects <ul><li>More species of insects exist then all other animal groups combined. </li></ul><ul><li>More than 700,000 species of insects have been classified, and scientists identify more each year. </li></ul>Arthropods 3 <ul><li>Insects have three body regions —a head, a thorax, and an abdomen. </li></ul>
  58. 66. Head <ul><li>An insect’s head has a pair of antennae, eyes, and a mouth. </li></ul><ul><li>The antennae are used for touch and smell. </li></ul>Arthropods 3 <ul><li>The eyes are simple or compound. Simple eyes detect light and darkness. </li></ul><ul><li>Compound eyes contain many lenses and can detect colors and movement. </li></ul>
  59. 67. Thorax <ul><li>Three pairs of legs and one or two pairs of wings, if present, are attached to the thorax. </li></ul><ul><li>Insects are the only invertebrate animals that can fly. </li></ul>Arthropods 3 <ul><li>Flying allows insects to find places to live, food sources, and mates. </li></ul><ul><li>Flight also helps them escape from their predators. </li></ul>
  60. 68. Abdomen <ul><li>The abdomen is where the reproductive structures are found. </li></ul><ul><li>Insects have an open circulatory system that carries digested food to cells and removes wastes. </li></ul>Arthropods 3 <ul><li>Insects have openings called spiracles (SPIHR ih kulz) on the abdomen and thorax through which air enters and waste gases leave the insect’s body. </li></ul>
  61. 69. From Egg to Adult <ul><li>Grasshoppers, silverfish, lice, and crickets undergo incomplete metamorphosis. </li></ul>Arthropods 3 <ul><li>Many insects go through changes in body form called </li></ul>metamorphosis (me tuh MOR fuh sihs).
  62. 70. From Egg to Adult <ul><li>Many insects —butterflies, beetles, ants, bees, moths, and flies —undergo complete metamorphosis. </li></ul><ul><li>The stages of complete metamorphosis are egg, larva, pupa, and adult. </li></ul>Arthropods 3 Click box to view movie.
  63. 71. Obtaining Food <ul><li>Grasshoppers and ants have large mandibles (MAN duh bulz) for chewing plant tissue. </li></ul>Arthropods 3 <ul><li>Butterflies and honeybees are equipped with siphons for </li></ul>lapping up nectar in flowers.
  64. 72. Obtaining Food <ul><li>Praying mantises eat other animals. </li></ul><ul><li>External parasites, such as mosquitoes, fleas, and lice, drink the blood and body fluids of other animals. </li></ul>Arthropods 3 <ul><li>Silverfish eat things that contain starch and some moth larvae eat wool clothing. </li></ul>
  65. 73. Insect Success <ul><li>Most insects have short life spans, so genetic traits can change more quickly in insect populations than in organisms that take longer to reproduce. </li></ul><ul><li>Because insects generally are small, they can live in a wide range of environments and avoid their enemies. </li></ul>Arthropods 3
  66. 74. Insect Success <ul><li>Many species of insects can live in the same area and not compete with one another for food, because many are so specialized in what they eat. </li></ul><ul><li>Protective coloration, or camouflage, allows insects to blend in with their surroundings. </li></ul>Arthropods 3
  67. 75. Arachnids <ul><li>Spiders, scorpions, mites, and ticks are examples of arachnids (uh RAK nudz). </li></ul>Arthropods 3 <ul><li>They have two body regions—a head-chest region called the cephalothorax (se fuh luh </li></ul>THOR aks) and an abdomen.
  68. 76. Arachnids Arthropods 3 <ul><li>Arachnids have four pairs of legs but no antennae. </li></ul><ul><li>Many arachnids are adapted to kill prey with venom glands, stingers, or fangs. </li></ul><ul><li>Others are parasites. </li></ul>
  69. 82. Scorpions <ul><li>Arachnids that have a sharp, venom-filled stinger at the end of their abdomen are called scorpions. </li></ul>Arthropods 3 <ul><li>Unlike other arachnids, scorpions have a pair of well-developed appendages —pincers —with which they grab their prey. </li></ul>
  70. 83. Spiders <ul><li>Because spiders can’t chew their food, they release enzymes into their prey that help digest it, then sucks it back into its mouth. </li></ul>Arthropods 3
  71. 84. Spiders Arthropods 3 <ul><li>Oxygen and carbon dioxide are exchanged in book lungs. </li></ul><ul><li>Openings on the abdomen allow these gases to move into and out of the book lungs. </li></ul>
  72. 85. Mites and Ticks <ul><li>Most mites are animal or plant parasites, but some are not like the mites that live in the follicles of human eyelashes. </li></ul>Arthropods 3 <ul><li>Most mites are so small that they look like tiny specs to the unaided eye. </li></ul><ul><li>Ticks attach to their host’s skin and remove blood through specialized mouthparts. </li></ul><ul><li>Diseases carried by ticks include Lyme disease and Rocky Mountain spotted fever. </li></ul>
  73. 86. Centipedes and Millipedes <ul><li>Two groups of arthropods —centipedes and millipedes —have long bodies with many segments and many legs, antennae, and simple eyes. </li></ul>Arthropods 3 <ul><li>They can be found in damp environments, including in woodpiles, under vegetation, and in basements. </li></ul><ul><li>Centipedes and millipedes reproduce sexually. They make nests for their eggs and stay with them until the eggs hatch. </li></ul>
  74. 87. Centipedes and Millipedes <ul><li>Centipedes hunt for their prey, which includes snails, slugs, and worms. </li></ul>Arthropods 3 <ul><li>They have a pair of venomous claws that they use to inject venom into their prey. </li></ul><ul><li>Millipedes feed on plants and decaying material and often are found under the damp plant material. </li></ul>Click image to view movie.
  75. 88. Crustaceans <ul><li>Crabs, crayfish, shrimp, barnacles, pill bugs, and water fleas are crustaceans. </li></ul>Arthropods 3 <ul><li>Crustaceans have </li></ul>one or two pairs of antennae and mandibles, which are used for crushing food. Most crustaceans live in water, but some live in moist environments on land.
  76. 89. Crustaceans <ul><li>Crustaceans have five pairs of legs. </li></ul>Arthropods 3 <ul><li>The first pair of legs are claws that catch and hold food. </li></ul><ul><li>The other four pairs are walking legs. </li></ul><ul><li>They also have five pairs of appendages on the abdomen called swimmerets. </li></ul><ul><li>If a crustacean loses an appendage, it will grow back, or regenerate. </li></ul>
  77. 90. Value of Arthropods <ul><li>Arthropods are a source of food for many animals, including humans. </li></ul>Arthropods 3 <ul><li>Bees, butterflies, moths, and flies pollinate crops. </li></ul><ul><li>Bees manufacture honey, and silkworms produce silk. </li></ul><ul><li>Many insects and spiders are predators of harmful animal species. </li></ul>
  78. 92. Value of Arthropods <ul><li>Not all arthropods are useful to humans. Almost every cultivated crop has some insect pest that feeds on it. </li></ul>Arthropods 3 <ul><li>Many arthropods —mosquitoes, tsetse flies, fleas, and ticks —carry human and other animal diseases. </li></ul><ul><li>In addition, weevils, cockroaches, carpenter ants, clothes moths, termites, and carpet beetles destroy food, clothing, and property. </li></ul>
  79. 93. Controlling Insects <ul><li>One common way to control problem insects is by insecticides. </li></ul>Arthropods 3 <ul><li>However, many insecticides also kill helpful insects. </li></ul><ul><li>Another problem is that many toxic substances that kill insects remain in the environment and accumulate in the bodies of animals that eat them. </li></ul>
  80. 94. Controlling Insects <ul><li>Different types of bacteria, fungi, and viruses are being used to control some insect pests. </li></ul>Arthropods 3 <ul><li>Other biological controls include using sterile males or naturally occurring chemicals that interfere with the reproduction or behavior of insect pests. </li></ul>
  81. 95. Origin of Arthropods <ul><li>Because of their hard body parts, arthropod fossils are among the oldest and best-preserved fossils of many-celled animals. </li></ul>Arthropods 3 <ul><li>Scientists hypothesize that arthropods probably evolved from an ancestor of segmented worms. </li></ul>
  82. 96. 3 Section Check Question 1 The word arthropoda means_______. A. many bristles B. head-footed C. little rings D. jointed foot
  83. 97. 3 Section Check Answer The answer is D. Crabs are an example of an arthropod.
  84. 98. 3 Section Check Question 2 Which is NOT one of the three body regions of an insect? A. abdomen B. appendage C. head D. thorax
  85. 99. 3 Section Check Answer The answer is B. Insect bodies consist of a head, thorax, and abdomen.
  86. 100. 3 Section Check Question 3 Which is an arachnid? A. butterfly B. conch C. earthworm D. tick
  87. 101. 3 Section Check Answer The answer is D. Arachnids have two body regions and four pairs of legs, but no antennae.
  88. 102. Echinoderm Characteristics <ul><li>Echinoderm (ih KI nuh durm) are found in oceans all over the world. </li></ul><ul><li>Echinoderms have a hard endoskeleton covered by a thin, bumpy, or spiny epidermis. </li></ul>Echinoderms 4 <ul><li>They are radically symmetrical, which allows them to sense food, predators, and other things in their environment from all directions. </li></ul>
  89. 103. Echinoderm Characteristics <ul><li>All echinoderms have a mouth, stomach, and intestines. </li></ul><ul><li>They feed on a variety of plants and animals. </li></ul>Echinoderms 4 <ul><li>Others feed on dead and decaying matter called detritus (de TRI tus) found on the ocean floor. </li></ul><ul><li>Echinoderms have no head or brain, but they do have a nerve ring that surrounds the mouth. </li></ul>
  90. 104. Water-Vascular System <ul><li>A characteristic unique to echinoderms is their water-vascular system. </li></ul>Echinoderms 4 <ul><li>It allows them to move, exchange carbon dioxide and oxygen, capture food, and release wastes. </li></ul>
  91. 105. Water-Vascular System Echinoderms 4 <ul><li>The water-vascular system is a network of water-filled canals with thousands of tube feet connected to it. </li></ul>
  92. 106. Water-Vascular System <ul><li>Tube feet are hollow, thin-walled tubes that each end in a suction cup. </li></ul>Echinoderms 4 <ul><li>As the pressure in the tube feet changes, the animal is able to move along by pushing out and pulling in its tube feet. </li></ul>
  93. 107. Types of Echinoderms <ul><li>Approximately 6,000 species of echinoderms are living today. </li></ul><ul><li>Of those, more than one-third are sea stars. </li></ul>Echinoderms 4 <ul><li>The arms are lined with thousands of tube feet. </li></ul><ul><li>Sea stars use their tube feet to open the shells of their prey. </li></ul>
  94. 109. Types of Echinoderms <ul><li>Sea stars reproduce sexually when females release eggs and males release sperm into the water. </li></ul><ul><li>Females can produce millions of eggs in one season. </li></ul>Echinoderms 4 <ul><li>Sea stars also can repair themselves by regeneration. </li></ul><ul><li>If a sea star loses an arm, it can grow a new one. </li></ul>
  95. 110. Brittle Stars <ul><li>Brittle stars have fragile, slender, branched arms that break off easily. </li></ul><ul><li>This adaption helps a brittle star survive attacks by predators. </li></ul>Echinoderms 4 <ul><li>Brittle stars quickly regenerate lost parts. </li></ul><ul><li>They live hidden under rocks or in litter on the ocean floor. </li></ul><ul><li>Brittle stars use their flexible arms for movement instead of their tube feet. </li></ul>
  96. 111. Sea Urchins and Sand Dollars <ul><li>Sea urchins, sea biscuits, and sand dollars are disk- or globe-shaped echinoderms covered with spines. </li></ul>Echinoderms 4 <ul><li>Some sea urchins have sacs near the end of the spines that contain toxic fluid that is injected into predators. </li></ul><ul><li>The spines also help in movement and burrowing. </li></ul>
  97. 112. Sea Cucumbers <ul><li>Sea cucumbers are soft-bodied echinoderms that have a leathery covering. </li></ul>Echinoderms 4 <ul><li>They have tentacles around their mouth and rows of tube feet on their upper and lower surfaces. </li></ul>
  98. 113. Value of Echinoderms <ul><li>Echinoderms are important to the marine environment because they feed on dead organisms and help recycle materials. </li></ul>Echinoderms 4 <ul><li>Sea urchins control the growth of algae in coastal areas. </li></ul>
  99. 114. Value of Echinoderms Echinoderms 4 <ul><li>Sea urchin eggs and sea cucumbers are used for food in some places. </li></ul><ul><li>Many echinoderms are used in research and some might be possible sources of medicines. </li></ul><ul><li>Sea stars are important predators that control populations of other animals. </li></ul>
  100. 115. Origin of Echinoderms Echinoderms 4 <ul><li>A good fossil record exists for echinoderms. </li></ul><ul><li>Echinoderms date back more than 400 million years. </li></ul><ul><li>The earliest echinoderms might have had bilateral symmetry as adults and may have been attached to the ocean floor by stalks. </li></ul>
  101. 116. Origin of Echinoderms Echinoderms 4 <ul><li>Scientists hypothesize that echinoderms more closely resemble animals with backbones than any other group of invertebrates. </li></ul><ul><li>This is because echinoderms have complex body systems and an embryo that develops the same way that the embryos of animals with backbones develop. </li></ul>
  102. 117. Question 1 In echinoderms, the _______ is a network of water-filled canals with thousands of tube feet connected to it which allows for movement, exchange of carbon-dioxide and oxygen, capture of food and release of waste. 4 Section Check
  103. 118. Answer The answer is water-vascular system. The water-vascular system is unique to echinoderms. 4 Section Check
  104. 119. Question 2 Which letter corresponds with the tube feet? 4 Section Check
  105. 120. Answer The letter C represents the tube feet. Tube feet are hollow, thin-walled tubes that each end in suction cup. They allow sea stars to move. 4 Section Check
  106. 121. 4 Section Check Question 3 Which is a survival tactic of an echinoderm? A. arms break off easily B. jet propulsion C. pinchers D. venom
  107. 122. 4 Section Check Answer The answer is A. Brittle stars have arms that break off easily if they are grabbed by a predator, allowing for escape. The lost parts regenerate quickly.
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  109. 124. End of Chapter Summary File