A Closer Look at Arthropods 701 DO NOT EDIT--Changes Must Be Made Through “File Info” Correctionkey=A

Home , Appendage, Arachnid, Archaea (spider), Arthropod exoskeleton, Map (butterfly), Spiracle (arthropods)

CorrectionKey=A DO NOT EDIT--Changes mustbemadethrough “File info” Unit 700 CHAPTER B most abundantanddiverse ofall animals. ONLINE Labs 24.4 24.5 24.2 24.3 24 24.1 Online Bi Online ■■ ■■ ■■ ■■ ■■ ■■ i Determining TimeofDeath UsingEntomology Identifying Arthropods inaDecomposer System Inside aCrayfish Daphnia andHeart Rate Hatching BrineShrimp QuickLab g Id

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Q What is the relationship between these two insects? Arthropod predators such as this digger wasp help to keep an important balance among Earth’s invertebrates. This digger wasp has captured a meal, not for itself but for its young. The wasp will deposit the live, but paralyzed, grasshopper into a burrow she has constructed. She will then lay a single egg next to the grasshopper so when the egg hatches the larva will have a fresh meal.

R E a d IN G T o o lb o x This reading tool can help you learn the material in the following pages.

USING LANGUAGE Your Turn Classification Categories are groups of things that Read the following sentences. Identify the category and have certain characteristics in common. Members of a members of that category in each sentence. category may differ from one another, but they share the 1. The Great Lakes include Huron, Ontario, Michigan, characteristics that make them part of the same category. Erie, and Superior. You can find members of a category by looking for words 2. Most European countries, such as Germany, France, such as include, such as, and are. and Italy, use a currency called the euro. 3. Scorpions, mites, and spiders are chelicerates— relatives of insects.

Chapter 24: A Closer Look at Arthropods 701 DO NOT EDIT--Changes must be made through “File info” CorrectionKey=A

24.1 Arthropod Diversity

7a, 7e, 8c Key Concept Arthropods are the most diverse of all animals. MAIN IDEAS VOCABULARY Arthropod features are highly adapted. arthropod Arthropod exoskeletons serve a variety of functions. exoskeleton Arthropod diversity evolved over millions of years. chitin appendage segmentation Connect to Your World Earth is truly ruled by bug-eyed monsters. In just about every way, arthropods are the most successful animal phylum on Earth. More than three-fourths of all known 7A analyze and evaluate how evidence of common ancestry animals—more than 1 million species—are arthropods. They play an important role in among groups is provided by the every ecosystem on the planet. What makes this phylum so interesting? Arthropods fossil record, biogeography, and homologies, including anatomical, are as diverse in shape and size as any life form on Earth and are the result of millions molecular, and developmental; of years of adaptation. 7E analyze and evaluate the relationship of natural selection to adaptation and to the development of diversity in and among species; 8C compare characteristics of MAIN IDEA 7e, 8c taxonomic groups, including archaea, bacteria, protists, fungi, plants, and animals Arthropod features are highly adapted. Without knowing it, almost everywhere you go, you are interacting with arthropods. They can be found in the carpet you walk on and in the bed where you sleep. An arthropod is an invertebrate animal with an exoskeleton made of Biology IDEO chitin; a series of paired, jointed appendages; and segmented body parts. V CLIP HMDScience.com Arthropod Characteristics

GO ONLINE The entire surface of an arthropod’s body is covered by a protective exoskel- Arthropod Anatomy eton. An exoskeleton is an external skeleton that supports the animal’s tissues against gravity. Arthropods, such as the rhino beetle in FIGURE 1.1, have exoskeletons made of proteins and chitin. Chitin (KYT-uhn) is a long organic molecule made of sugars—similar to plant cellulose—that is arranged in layers. In each FIGURE 1.1 The hard exoskeleton of this rhino beetle is constructed layer, fibers are laid out parallel to one another. But fibers in different layers of layers of chitin that help protect point in different directions, forming a biological “plywood” that is very tough it from predators. and strong. Like armor, chitin also protects the animal from predators. Jointed appendages were an important adaptation during the evolution of arthropods. An appendage is an extension of an organism’s body. It can be used for walking, swimming, sensing, manipulating food, or chewing. Arthro- pods can have six, eight, ten, or even hundreds of appendages. The appendages can be shaped like rakes, tweezers, nutcrackers, hammers, or paddles. Arthropods have an incredible variety of body forms. Some are microscopic, while others are quite large. For example, some tropical stick insects and millipedes can reach 30 centimeters (1 ft) in length, and spider crabs can have an arm span of 3.6 meters (12 ft). But all arthropod bodies are segmented for specific functions. Segmentation describes how an arthropod’s body parts are divided into similar sections that have each evolved for a different function. ©Hans Cristoph Kappel/Nature Picture Library

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trilobite ©Sinclair Stammers/Photo Researchers, Inc.; crab ©Pete Oxford/Nature Picture Library; scorpion ©Stephen Dalton/Photo Researchers, Inc.; butterfly ©Holger Wulschlaeger/ShutterStock; centipede ©Tom McHugh/Photo Researchers, Inc. ar Infer evolution hasled to manydifferent bodyforms andfunctions. Arthropods are adiverse group ofanimals. ofyears Millions of 1.3 FIGURE and adapt crabs Crab C fossil and living placedinto can arthropod species be one of five groups animals manyClassifying with so differences but might difficult, most seem Groups Arthropod thropods we today? see thropods • • • • • rus

wa Trilobites Cru Myr Ins Che zoic marine ecosystems for nearly 300million years. As you in can see FIGURE 1.2, 1.2, FIGURE are terrestrial and have six legs. mosquitoes areThough group this insects. all diverse, is very most insects animals such as ants, butterflies, bees, moths, cockroaches, and flies, thatparts are for used tearing food. their scorpions.sea animals These share daggerlike of mouth- aset specialized includes horseshoe crabs, scorpions, spiders, mites, ticks, and extinct the sucking up muck, algae, or animals soft floor. from sea the many delicate legs. Most of 4000known the were species bottom feeders, and Acentrallobes. body outgrowths of shell on each side covered their in centipedes poisonous bear fangs for capturing prey. ments, such as leaf litter, decaying wood, or moist soil. The first pair of legs canspecies grow up to afoot long. generally They live inhumid environ- are most the distinctive characteristics of myriapods. the The largest are centipedes and Their long millipedes. and many bodies pairs of legs lobsters, microscopic copepods, oysterlike barnacles, and armored pill bugs. on land. Crustaceans are a diverse group that includes huge king crabs and STAY-shuhnz) are found in all of the oceans, freshwater streams, and even

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©Roger Steene/Image Quest Marine FIGURE mandible carapace abdomen cephalothorax crustacean VOCABULARY in oceans. can this animals bacteria, protists, fungi,plants, and taxonomic groups, including archaea, 8C compare characteristics of of diversity inandamongspecies; adaptation andto thedevelopment relationship ofnatural selection to 7E analyze andevaluate the molecular, anddevelopmental; homologies, includinganatomical, fossil record, biogeography, and among groups isprovided by the how evidence ofcommon ancestry

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y thropods. species ofspecies filter-feeding crustaceans. that constitute they an important source food for and whales, fish, many Zooplankton, as areadults and small copepods krill, but very are abundant so humans. But there are numerous also of species microscopic crustaceans. lobsters, and crabs, are source food for aprimary birds, fish, and even seals, significant source food for larger animals. Large crustaceans, such as shrimp, others scavenge animals dead and plants. Most importantly, crustaceans are a Crustaceans

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the cephalothoraxthe and abdomen. the have segmentsalso that body contain fused two regions, ages that are for used many different Decapods purposes. “ten legs,” have decapods all so five pairs of jointed append- fromthem other crustaceans. The name decapod means figure 2.4, figure fresh water. Some crabs, such as coconut the crab shown in environments, but such species as crayfish have invaded crabs, and many others. live Decapods primarily insaltwater and shrimp, as well as hermit crabs, cousins their king the of adecapod.This familiar group includes lobsters, crabs, When you of you think acrustacean, are probably thinking Decapods arethey similar inhow all develop they into adult the form. anatomy inboth Crustaceans vary and structure. However, hard appendages mandibles. called that are thought predators. to startle spiny lobsters antennae rub against cephalothorax their to make loud calls Daphnia,flea antennae hairy the use as oars to move around. Many of species locate mates, and avoid predators. Some crustaceans, such as tiny the water throughflick water, the appendages these crustaceans use to smell food, ag MAI

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Barnacles, Isopods, and Tongue Worms Other species of crustaceans look nothing like a “typical” decapod. Although these species are different in structure from other crustaceans, scientists discovered mouth from developmental evidence that most crustaceans legs pass through similar phases as they grow into adults. stomach Almost all juvenile crustaceans pass through a free-swimming planktonic larval stage. The most common of these larva forms is the nauplius larva. A nauplius larva has a carapace and six long, feathery cement gland limbs. When scientists looked at newly hatched barnacles and tongue worms, they found nauplius larvae. Only crustaceans have nauplius larvae, so both groups are recognized as crustaceans. But as they grow into their adult form, these crustaceans look very different from any other crustacean. • Barnacles Barnacles are sessile, or nonmoving, filter feeders wrapped in a heavily calcified shell. They live attached to the surface of rocks, boats, sea turtle shells, and even the skin of humpback whales, such as the one shown in FIGURE 2.5. Barnacles have turned their carapace into a saclike “mantle” (similar to that found in a mollusk) that secretes a calcium shell. Inside the shell, the animal sits on its head and sweeps food into its mouth FIGURE 2.5 Attached to the skin of this humpback whale, with its legs. thousands of barnacles use the • Isopods Isopods have flattened bodies and seven pairs of legs. Most whale’s constant movement species are marine and freshwater scavengers. Pill bugs and wood lice through the water to filter food from the water. belong to a group of isopods that have become completely terrestrial. These animals usually live in damp habitats and eat rotting plants. • Tongue worms Tongue worms are parasites that live in the lungs and nasal passages of vertebrates. They have no eyes, mandibles, or antennae, and they have lost most of their limbs. Despite this, molecular evidence shows tongue worms to be most closely related to crustaceans. Analyze What evidence helped scientists to classify barnacles and tongue worms as crustaceans? 7a ©Wayne ©Wayne Levin/Getty Images

Self-check Online HMDScience.com 24.2 Formative Assessment GO ONLINE Reviewing Main Ideas Critical thinking CONNECT TO 1. What characteristics make 3. Summarize Draw a food web that Evolution crustaceans different from includes at least three different types 5. Lobster claws can grow other arthropods? 8c of arthropods. extremely large. What 2. What are some of the different 4. Infer How did the discovery of selective pressures may have functions of arthropod appendages? nauplius larvae allow scientists to led to the evolution of such categorize barnacles and tongue large appendages? 7E worms as crustaceans? 7a

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online biology 711 HMDScience.com CorrectionKey=A DO NOT EDIT--Changes mustbemadethrough “File info” Unit 712 FIGURE trachea spiracle lung book arachnid chelicerate VOCABULARY made into aneasy meal. web, where they are trapped and attracts insects to thespider’s of thespinyspideractually plants, andanimals archaea, bacteria, protists, fungi, taxonomic gorups, including data; 8ccompare characteristics of inferences, andpredict trends from 2G analyze, evaluate, make and precision usingtools...; make measurements withaccuracy qualitative andquantitative data and

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3.1 Animals 24.3

The brightcolor 2F, 2G, 8c Arachnids ation Arachnids are largestArachnids the groupofchelicerates. and spread by atinyarachnid called adeertick. surprise temperature shot upto 102 degrees. Atripto thedoctor gave herparents astartling into abull’s-eye that was 6incheswide.Emily began complaining ofaches, andher At first, thebumpon Emily’s back looked like aninsectbite. Butsoon therash grew Your to World Connect Ke

Arachnids have four different adaptations that reduce water loss. evolved adaptations that allowed water to them conserve and live on land. eight legs, fanglike pincers that inject venom, and the ability to produce silk. Deer ticks areDeer chelicerates—arthropods without mandibles. spider shown in more than 80 percent of all chelicerate species. spiders are two of these groups. Arachnids are the third group, representing acephalothoraxsections: and an abdomen. pedipalps, are to grasp and used subdue prey. Chelicerate have bodies two andfood shove it into aholelike mouth. of Asecond set appendages, called ages form fanglike mouthparts chelicerae, called which are to mash used up which include four pairs append- of of legs. One walking set modified highly (kih-LIHS-ur-ayts) lack antennae also and have six pairs of appendages, Book • Waterproof • Malpighian • MAI MAI C

o Evi evaporate across skin. the book lungsbook that allow to them breathe air. The metabolic wastes. tubulesee-uhn) allow spiders to minimize loss of water excreting while chamber covered by aplate of abdominal cuticle. for water loss. To prevent water lungs loss, book are enclosedinahumid provide alarge for surface gas exchange but create also large avery surface many hollow thin, sheets of tissue that like look pages the of They abook. Arachnids have evolved into a diverse group. Arachnids are thelargest group ofchelicerates. N —Emily had Lymedis n N ID dence from fossils nearly 400million years old suggests that arachnids c ID re are three main groups of chelicerates. The horseshoe crabs and sea ept

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An ara Excr are a terrestrial group of chelicerates characterized by ease. Thisdisease iscaused by bacteria that iscarried etory structures called Malpighian structures called etory (mal-PIHG- chnid’s cuticle is waterproof, water so cannot Book lungs Arachnids, such as the spiny are structures built of Chelicerates

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FIGURE 3.2 Arachnid Anatomy Arachnids have many unique adaptations for catching and consuming their prey. cephalothorax abdomen

eyes heart Biology VIDEO brain CLIP venom gland HMDScience.com go online spinnerets Arthropod Respiration book lung

spiracle

• Spiracles Some species of arachnids use spiracles to breathe. Spiracles are R E ADI N G TO OLB ox tiny holes on the abdomen that open and close to allow oxygen to enter. Oxygen flows through a series of tubes called tracheae. Tracheae (singular, VOCABULARY spiracle trachea) carry oxygen directly to the arachnid’s tissues. The word comes from the Latin word spirare meaning Explain How do the features of an arachnid allow it to live on land? “to breathe.”

MAIN IDEA 8c Arachnids have evolved into a diverse group. Spiders make up half of the more than 60,000 known arachnid species. They are predators that hunt or trap their prey. All spiders have the ability to make silk and produce venom. Silk is made by glands in the spider’s abdomen and released by modified appendages called spinnerets. Spiders use silk for building webs, wrapping prey and egg cases, building shelters, and producing drag lines that anchor the animal like a climber’s safety line. All spiders produce venom. Spiders inject venom into their prey through CONNECT TO modified chelicerae. Neurotoxic proteins paralyze the victim by attacking the Neurotransmitters central nervous system, and digestive enzymes in the venom begin to dissolve Neurotoxins in the venom of the prey from the inside. Among North American spiders, only the black widow spiders disrupt neurotransmitter and brown recluse spiders have venom that can affect a human, but many function and lead to paralysis of a victim. You will learn more species around the world have venom that can paralyze or even kill humans. about the nervous system and Mites, ticks, and chiggers are a large group of very small arachnids. Some neurotransmitters in Nervous species are less than 0.25 millimeters long. Many are parasites of plants and and Endocrine Systems. animals, sucking up sap or blood through their needlelike mouthparts. Scorpions are arachnids with huge pincers for grabbing their prey after it has been injected with venom from a stinger at the end of their tail. Scorpions hunt at night by feeling the vibrations made as their prey moves.

Chapter 24: A Closer Look at Arthropods 713 CorrectionKey=A DO NOT EDIT--Changes mustbemadethrough “File info” Unit 714 24.3 AA ANALSIS I LYS A N A DATA 3. 2. 1. Re summarized inthetable below. strands inrelationship to thebodylength ofthespider. Theirresults are another. Scientistsstudyingspidersilkmeasured thediameter ofsilk be strong enoughto thespiderasitmoves support from oneplace to webs to capture prey orto safely wrap theireggs.that Itisimportant silk Spiders produce silkfor awidevariety ofpurposes. Somespiders build C

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24.4 Insect Adaptations

Key Concept VOCABULARY Insects show an amazing range of adaptations. incomplete metamorphosis MAIN IDEAS complete metamorphosis Insects are the dominant terrestrial arthropods. pupa Insects undergo metamorphosis. Insects have adapted to life on land.

Connect to Your World Everywhere you turn, there are more of them. They are under your feet, flying over your head, nestled in your clothing fibers, and waiting for you to go to bed. Insects are virtually everywhere, and many times you may not even know it. With more than 900,000 known species, insects are the single largest and most diverse group of animals on the planet.

MAIN IDEA Insects are the dominant terrestrial arthropods. Insects are an incredible success story. Like the arachnids, they invaded land T’ ing! maz around 400 million years ago. They have many of the same adaptations for A Video Inquiry terrestrial life as arachnids do. Insects have moved into virtually every ecologi- HMDScience.com cal niche, which has helped them diversify into the largest group of animals. go online Insects can be found in the most extreme places, including hot sulphur Zombie Ants springs and the soil of Antarctica. They are also found in streams and ponds. Though some species live in the marine intertidal zone, they are largely absent in the seas, where crustaceans are the dominant arthropods. Due to such a wide distribution, scientists are discovering new species of insects each day. All insects have a body with three parts: a head, a central region called the FIGURE 4.1 This potter wasp thorax (THAWR-aks), and an abdomen, as shown in FIGURE 4.1. The thorax illustrates the three-part body structure of all insects: head, has three pairs of legs, and most adult insects also have two pairs of wings. thorax, and abdomen. Insects usually have one pair of antennae and one pair of compound eyes. Many have mandibles that they use to chew up their head thorax food, but others have modified mouthparts for more specialized feeding behaviors. abdomen Some insect species live in colonies of hundreds or thousands of individuals. Within these colonies, complex social structures exist. Individuals perform specific jobs that help the colony be successful. Scientists think that an insect’s genetic code deter- mines what role it will play in a colony. Compare and Contrast How are insects similar to and different from crustaceans and arachnids? ©WoodyStock/Alamy ©WoodyStock/Alamy Ltd

Chapter 24: A Closer Look at Arthropods 715 DO NOT EDIT--Changes must be made through “File info” CorrectionKey=A

MAIN IDEA Insects undergo metamorphosis.

R E ADI N G TO OLB ox Insects do not develop the same way you do. When you were first born, you had all of the same body parts as an adult. The same is not true of most VOCABULARY insects. Some insects, such as butterflies and mosquitoes, go through dramatic The word metamorphosis physical changes between their immature and mature forms. comes from the Greek word metamorphoun, which means Some insects, such as grasshoppers and cock- “to transform.” roaches, look like miniature adults when they hatch. This pattern of development, illustrated in FIGURE 4.2, adult is incomplete metamorphosis (meht-uh-MAWR- nymph stages fuh-sihs), or direct development. These immature insects are often called nymphs. They have six legs and a head, thorax, and abdomen, but they do not have wings or sex organs. Nymphs get larger with each molt but only grow wings and sexual organs during the later molting stages. In the process of complete metamorphosis, illustrated in FIGURE 4.3, young insects do not look like egg adults but molt and change their form as they mature. Young insects hatch out of eggs as wormlike larvae whose bodies are not clearly divided into a head, thorax, and abdomen, and they often lack legs or antennae. As they grow, FIGURE 4.2 In the process of larvae pass through several molts, getting bigger each time, until they molt incomplete metamorphosis, a into an inactive form called a pupa. Inside the pupa, some tissues are broken nymph appears to be a miniature copy of the adult insect. But on down for energy, and others are reorganized to produce a completely new closer inspection, these immature body form. When the adult insect emerges from the pupa, it looks very insects lack important features different from a larva. It has wings, legs, and compound eyes, and is ready such as wings and sex organs. to fly away and begin its search for a mate. Connect Which type of metamorphosis more closely resembles human development? Explain.

MAIN IDEA Insects have adapted to life on land. CONNECT TO Insects have several adaptations that allow them to be successful terrestrial Plants species. Just like arachnids, insects retain water for survival using exoskel- Recall from the chapter Plant etons, Malpighian tubules, spiracles, and tracheae. Gases move through the Structure and Function that tracheae by diffusion, and spiracles can close to prevent water loss. Some stomata are holes in the leaves insects can also pump air through their bodies by rapidly squeezing and of plants that open and close to control transpiration and gas expanding their tracheae. The water-conserving characteristics that are exchange. Many arthropods use shared by insects and arachnids are an example of convergent evolution. In spiracles in the same way, both groups, individuals that could survive longer without water were better opening and closing them to control water and gas exchange. able to reproduce. In this way, natural selection independently moved both groups toward similar features that allowed them to carry out similar water- conserving functions.

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FIGURE 4.3 Complete Metamorphosis of a Monarch Butterfly

The complete metamorphosis of an insect involves two completely different forms: a juvenile form and an adult form. This prevents adults and juveniles from competing for the same resources.

1 Larva A butterfly larva is also called a caterpillar. After hatching, caterpillars spend most of their time feeding and also molt their skin as they grow larger.

thoracic legs

4 Eggs Female butterflies deposit eggs on the underside of a 2 Pupa The caterpillar leaf. Three to six days heart sheds its skin one final later, the small eggs time and forms a shell hatch into larvae. silk gland called a chrysalis. Inside, dramatic changes transform the pupa.

stomach

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3 Adult The monarch butterfly that emerges from the chrysalis 9 to 14 days later is very different from the caterpillar larva. The butterfly is now an adult and begins the life cycle again. spiracles

rectum

CRITICAL During which phase of development do you think the monarch butterfly is most VIEWING vulnerable to predators? ©Wayne ©Wayne Levin/Getty Images

Chapter 24: A Closer Look at Arthropods 717 DO NOT EDIT--Changes must be made through “File info” CorrectionKey=A

Only four groups of animals have evolved true flight: insects, the extinct pterosaurs, bats, and birds. Insects conquered the air first and have been flying for nearly 400 million years. Insect wings are long flat extensions of the exoskeleton that stick out of the animal’s back. At the base of each wing are muscles that move the wing up and down, allowing insects, such as the bee in figure 4.4, to fly. But it takes a great deal of energy to move a wing up and down. The insect exoskeleton has evolved in ways that conserve the energy needed for flight. By enabling the insect to reuse the stored kinetic energy created by wing movement, muscles attached to wings do only part of the work. For example, when a diver uses a springboard, the kinetic energy of the diver’s mass is stored as the board flexes. When the board rebounds, this energy is released and the diver is shot into the air. Like a springboard, insect cuticle is slightly flexible. As the FIGURE 4.4 Bees can beat their wing moves, it exerts force on the exoskeleton, causing it to flex and slightly wings 200 times per second. This deform. When the cuticle rebounds, the stored kinetic energy moves the wing ability allows them to hover in back to its original position. In this way, an insect reduces the amount of one place while looking for food. energy needed for flying, leaving more energy available for feeding and reproduction. Insects feed on many different foods. Over time, insect mouth shapes have taken on a variety of forms according to their diets. Generally speaking, R E ADI N G TO OLB ox insects eat by either chewing or sucking. Insects such as butterflies and moths TAKING NOTES that feed on plant nectar and fruits have a long, strawlike mouth called a Use a Venn diagram to proboscis (proh-BAHS-sihs). A mosquito also has a proboscis, but instead categorize insects based on it uses its mouth to suck blood from other animals . Other insects feed by their mouthparts. chewing their food. Ants, beetles, and dragonflies have chewing mouthparts, chewing both sucking which consist of mandibles adapted either to crushing leaves and plant stems, or to tearing apart flesh. Bees, wasps, and some flies are insects that have adapted to feed by both sucking and chewing. Contrast How might the chewing mouthparts of carnivorous and herbivorous insects be different? ©Mitsuhiko Imamori/Minden Pictures

Self-check Online HMDScience.com 24.4 Formative Assessment go online Reviewing Main Ideas Critical thinking CONNECT TO 1. What features make insects different 4. Hypothesize How might the Evolution from other arthropods? spiracles of a desert insect be 6. Hundreds of millions of years 2. What is the difference between different from the spiracles of a ago, spiders began to use silk complete metamorphosis and tropical rain forest insect? around the same time insects incomplete metamorphosis? 5. Infer Give two reasons why began to fly. Explain how natural selection affected 3. What are two major adaptations that flight has enabled insects to be these changes. helped insects to survive on land? so successful.

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©Mike Wilkes/Nature Picture Library FIGURE vector insecticide VOCABULARY and even homes. cause damage to crops, forests, plant. Arthropod pestspeciescan tissues, often thehost killing 24.5 5.1

Aphids devour plant Arthropods andHumans same resources.same sharemany ofthe humans and Arthropods humans have created manyconflicts. human diseases. Over time,theunavoidable interactions between arthropods and are used for food andfibers inmanyhumancultures, butother insectspecies spread crops andinfest others ourhomes.Still are predators that eat pests.Insectspecies pollinatorsimportant that fertilize humancrops. Others are peststhat destroy People have alove-hate relationship witharthropods. Somearthropods are Connect to Your World Ke

insects called aphids. called insects Aphids, shown in trees or plants, pepper you may clusters see of tiny bumps. bumps These are arthropods than people. For example, you when under look leaves the of apple humans for same the resources. Competition there because is are stiff far more foruse textiles,and food, building materials. arthropods These compete with Many arthropods are herbivores, and many of eat them same the plants people y MAI MAI C

o Some arthropods can spread humandiseases. Arthropods andhumansshare resources. manyofthesame N n N ID safer ways of controlling populations. pest discovered ways unique to the use characteristics of arthropods to find resistance causes humans to even larger use of doses toxin. the become resistantcan also through to insecticides natural This selection. predator through species process the of biomagnification. Arthropods dane and DDT, do not break down quickly. can They accumulate in cides are toxic to other animals, including people. Some, such as chlor toxic chemicals on plants can have unwanted Many side effects. - insecti chemical compound and that insects other kills arthropods. But spraying use insecticides to control insecticides use arthropod populations. An such as corn, wheat, and cotton. To prevent costly infestations, farmers remove enough sap to damage plant. the or kill But aphids live inlarge colonies. Hundreds of aphids on aplant can inside. Asingle aphid and is small cannot do much damage on its own. toparts pierce of walls cell the aplant and suck liquid up sugary the c ID ept E E To av Eac A AS

Arthropods andhumansinteract inmany ways. h year, arthropods cause millions of dollars indamage to crops oid potential the hazards of using scientists insecticides, have

figure 5.1, Chapter 24: ACloser Lookat Arthropods use their needlelike mouth- needlelike their use insecticide is a a is -

719 CorrectionKey=B DO NOT EDIT--Changes mustbemadethrough “File info” 720

arthropod vectors. list thediseases carried by Use amainidea diagram to T FIGURE to another. carrying pollen from oneflower helps to pollinate flowers by eastern tiger swallowtail butterfly to meal, anectar getting this import AKI Unit 8:Animals R Arthropod Vector Diseases E N ADI ant pollinators. Inaddition G 5.2 N O

N Many arthropods are TE G S Bubonic plague TOOLB o x Some arthropods can spread human diseases. can spread human arthropods Some ma Infer

to another.to and ticks. fleas, Humans are asource of to arthropods food such as mosquitoes, biting flies, targeted arthropodshelp can also to specific slow spread the of disease. which can fight then off future pathogen invasions. Theof use pesticides bydiseases delivering of doses small pathogen the to immune the system, Vaccinations have developed to protect been individuals from many of types tions. Many for methods controlling arthropod vectors have developed. been carry diseases. A diseases. carry • • • Malaria • Yellow • Bubonic • MAI nagement?

borer but is harmless to most other animals. gene makes aprotein that caterpillar kills such pests as European the corn thuringiensis, bacterium, Bacillus For example, Bt engineered corn has to been include agene from asoil such as ladybugs and parasitic wasps, IPMhelps to control species. pest includingmethods traps, insect physical barriers,and introduced predators on aplant crop by managing ecology. their By using avariety of other butnerves not found inother animal nerves. a neur to arthropods. One exampleInsecticides developedspecific canto be is Gen Int Africa, Asia,Africa, and and Central South America. 1950s by aprogram of DDT spraying. It common is still intropical regions of Europe. Malaria was largely eliminated intemperate countries during the yellow Like them. fever, was once malaria common United in the States and sites enter cells toemerging red breed, blood and periodically destroying eradication programs brought under control. disease the 20,000 people during construction the of Panama the canal before mosquito common and South inAfrica America.Yellow fever epidemicsnearly killed common United inthe States until early the of part 1900sand the is still to humanscarried by mosquitoes. causes The virus fever and bleeding. It was bubonic plague is controlled by antibiotics and improved hygiene. one-thirdbetween and one-half of people the living inEurope. Today, and 1600s.The the largest of epidemics, these 1347and between 1350,killed Outbreaks of bubonic plague devastated European cities1300s the between that has aflea fed when infections on an occur infected rat feeds on ahuman. normally rodents affects such as prairie dogs, squirrels, and rats. Human spreadDiseases by arthropods can have on serious effects human popula- What would be a disadvantage to introducing a predator insect for pest pest for insect apredator to introducing adisadvantage be would What N egrated management, pest or IPM,reduces number the ofpests insect ID etically modified plants modified etically made can to be resist species. pest particular E otoxin that receptor blocks aparticular that is common inarthropod

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FIGURE 5.3 Arthropod Vectors Arthropods are vectors for carrying diseases such as Lyme disease.

1 As the tick feeds on the host’s blood, 2 Inside the tick, the pathogens are 3 When the tick feeds on another microscopic pathogens pass from stable and do not affect the tick. host, pathogens are passed from deer to tick. (colored SEM tick; (LM; magnification 40003) the tick to the new host. magnification 153)

Analyze Though vectors can bring disease into human populations, explain why diseases carried by arthropods spread more quickly through the populations of other animals.

• West Nile virus is contracted from mosquito carriers that have previously CONNECT TO fed on birds infected with the virus. Originally discovered in Africa, West Immune System Asia, and the Middle East, the virus has spread throughout the world Vaccines can only work to and has been identified in 48 of the United States. Fever, headache, and prevent a disease; they cannot skin rashes are some of the minor symptoms, but the virus can lead to cure a person who is already sick. The human immune system meningitis or encephalitis, potentially fatal diseases. Scientists are currently has specifically designed cells working to control the spread of the virus. which work to fight diseases in your body. Infer Explain how an organism other than an arthropod could be a vector. (l) ©Rod Planck/Photo Researchers, Inc.; (inset) ©Volker Steger/Photo Researchers, Inc.; (c) ©Chu Tours-Joubert/Photo Researchers, Inc.; (r) ©Scott Camazine/Photo Researchers, Inc. Inc.; (r) ©Scott Camazine/Photo Researchers, Researchers, Tours-Joubert/Photo Inc.; (c) ©Chu Steger/Photo Researchers, Inc.; (inset) ©Volker (l) ©Rod Planck/Photo Researchers,

Self-check Online HMDScience.com 24.5 Formative Assessment go online Reviewing Main Ideas Critical thinking CONNECT TO 1. What are three effective ways of 3. Analyze What are the potential costs Natural Selection managing insect pest populations? and benefits of using an introduced 5. Describe a situation in which 2. How does a vector spread a disease predator to control a pest population? natural selection could lead such as malaria? 4. Connect What effect, if any, would to an arthropod population the development of a vaccine against that is resistant to pesticides. a tick-borne disease have on the tick population? Explain.

Chapter 24: A Closer Look at Arthropods 721 CorrectionKey=A DO NOT EDIT--Changes mustbemadethrough “File info” Unit 722

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CHAPTER 24 G N I D A E R

covering.” describe theterm exoskeleton could be“hard, outer vocabulary term below. For example, phrase ashort to Write precise ashort, phrase that defineseach Keep ItShort

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Use thediagram to answer thenext two questions. Interpreting Critical 28. 26. 24. 22. 25. 23. 27. Unit 8:Animals

spiders from growing anylarger thanthis? dinner plate. What anatomical features may prevent spider ofSouthAmerica, whichcan beaslarge asa Infer A might eliminate atermite colony? untreated. What are some ways inwhichahomeowner can destroy houses over thecourse ofafew years ifleft cellulose found inwood. They live inlarge colonies and Compare andC type ofmetamorphosis give thisspecies? phosis shown above. What adaptive advantage doesthis Identify or nose? and disadvantages ofhaving tracheae instead ofamouth through theirmouthornose. What are theadvantages out throughout thebody. Humanscan only breathe A Classify diagram? A whales? up ontheshore. How dothese barnacles get onto also befound attached to large whales that never swim see manybarnacles attached to rocks. Butbarnacles can belong? What dothey likely eat? leaves. To what group ofarthropods dothey likely animals withmanysets oflegs scurry away into the pply pply pply

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If so, what explanation mightexplain theoutlier? Interpret efficiency andcarapace length? habitat, food, andlifestyle. pressures were selected for itsfeatures, anddescribe its your hypothesis onitsancestors, what environmental Write abriefdescription ofthespecies,andinclude appendages andother features ofthisnew species. very different thanthey are today. Draw andlabel the yearsspecies 1million into thefuture. Arthropods are arthropod. Imagine that you are arthropod sampling Write Science Fiction Interpret similar anddifferent? what ways are thehuntingstyles ofarachnids andwasps potter wasp, huntnumerous speciesofarthropods. In Compare andContrast

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Biology End-of-Course Exam Practice

Record your answers on a separate piece of paper. THINK THROUGH THE QUESTION MULTIPLE CHOICE Remember that natural selection favors individuals with adaptations that allow them to survive and 2E, 11B reproduce. 1 Se t Up for Daphnia Experiment Daphnia Treatment 10A, 11C Group A f lashes of light from above 4 Yellow fever is caused by a virus that is trans- mitted by mosquitoes. Proof of yellow fever Group B f lashes of light from below vaccination is required before entering certain Group C no light countries. Which best describes how a blood test might provide evidence that someone has been Two students observed how a species of daphnia, vaccinated for yellow fever? a microscopic crustacean, responds to light. They A If someone has been vaccinated, they will have divided their daphnia into three groups with each large amounts of the virus in their blood. receiving a different light treatment. Based on their experimental design shown above, which B If someone has been vaccinated, they will have group served as a control? small doses of mosquito DNA in their blood. A Group A C If someone has been vaccinated, their blood will indicate an immune system response to B Group B the virus. C Group C D If someone has been vaccinated, there will be D neither Group A, B, or C no evidence of having been exposed to the virus in their blood. 10C 2 Sowbugs and pillbugs are terrestrial crustaceans 2G, 7B that feed primarily on decaying organic matter. 5 They are important to the stability of ecosystems Tril obite Abundance in the Fossil Record in part due to their role as — Millions of Years Ago (MYA) Fossil Record A producers 540 MYA trilobite fossils appear B predators 500 MYA peak of trilobite diversity C decomposers 450 MYA trilobite diversity drops D autotrophs 300 MYA trilobites uncommon 245 MYA to Present no trilobites 7C, 12A 3 Walking sticks are insects that look like parts of a Scientists have generated the above data based on plant. They are eaten by birds, lizards, and other hundreds of thousands of trilobite fossils that predators. Over many generations, natural have been identified and dated in the fossil selection has most likely favored individual record. What conclusion can be drawn from the walking sticks that — data shown above? A cannot be easily seen by predators A Trilobites existed on Earth for 540 million years. B look the most frightening to predators B Trilobite fossils began to decay 300 million C stand out the most to predators years ago. D do not have any predators C Trilobites may have gone extinct about 245 million years ago. D Trilobites were able to outcompete every other species 500 million years ago.

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