Reading Essentials for Biology Glencoe (794133), страница 79
Текст из файла (страница 79)
The female insect lays eggs in the hole.5. How do insects increasethe chances that offspringwill survive long enoughto reproduce?________________________________________________________________________Copyright © by Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.What happens during metamorphosis?After eggs are laid, the embryos develop and the eggs hatch.In some wingless insects, such as silverfish, the eggs hatch intosmall forms that look like tiny adults.
These insects molt severaltimes until they reach adult size. Many other species of insectsgo through a series of major changes in body structure asthey develop. Often, the adult insect does not resemble thejuvenile form of the insect. This series of changes, controlledby chemical substances in the animal, is called metamorphosis(me tuh MOR fuh sus).Insects that undergo metamorphosis usually go through fourstages on their way to adulthood: egg, larva, pupa, and adult. Thelarva is the free-living, wormlike stage of an insect, often called acaterpillar. As the larva eats and grows, it molts several times.The pupa (PYEW puh) stage of insects is a period of reorganization. Tissues and organs of the larva are broken down andreplaced by adult tissues.
Usually the insect does not move or feedduring the pupa stage. After a period of time, a fully formed adultemerges from the pupa.The series of changes that occur as an insect goes through theegg, larva, pupa, and adult stages is called complete metamorphosis. In winged insects that undergo complete metamorphosis, thewings do not appear until the adult stage.
More than 90 percentof all insects undergo complete metamorphosis.READING ESSENTIALS6. What is metamorphosis?________________________________________________________________________Chapter 28347NameDateClassSection28.2Diversity of Arthropods, continuedA Insects begin lifeas a fertilized egg.The egg hatchesinto a larva.B Larvae eat hugeamounts of foodto supply theenergy neededfor tremendousgrowth.C The pupa stage is anemerges from thepupa is sexuallymature.The advantage of complete metamorphosis is that larva do notcompete with adults for the same food. For example, butterflylarvae (caterpillars) feed on leaves.
Adult butterflies feed on nectarfrom flowers. The complete metamorphosis of a butterfly isshown above.What is incomplete metamorphosis?7. What are the differencesbetween a nymph and anadult?________________________________________________________________________Some insect species undergo a gradual or incomplete metamorphosis.
The insect only goes through three stages of development.The three stages are egg, nymph, and adult. A nymph, whichhatches from an egg, has the same general appearance as the adultbut is smaller. Nymphs may lack certain appendages, or haveappendages not seen in adults. A nymph cannot reproduce. Witheach nymph molt, it looks more like the adult. Wings begin toform and an internal reproductive system develops. Gradually, thenymph becomes an adult.
Grasshoppers and cockroaches areinsects that undergo incomplete metamorphosis.Origins of ArthropodsArthropods live successfully on every surface of Earth. Theirability to survive in just about every habitat is unequaled in348Chapter 28READING ESSENTIALSCopyright © by Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.D The adult insect thatoutwardly inactivestage in which cellsof the body arereorganized intoa new body form.NameDateClassSection28.2Diversity of Arthropods, continuedCopyright © by Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.the animal kingdom.
The success of arthropods is due in partto their varied life cycles, high reproductive output, and structural adaptations, such as small size, hard exoskeleton, andjointed appendages.8. Why have arthropodsbeen successful in somany habitats?How did arthropods evolve?________________________Arthropods most likely evolved from an ancestor of theannelids. As arthropods evolved, body segments became fused.They adapted for certain functions such as locomotion, feeding,and sensing the environment.
Segments in arthropods are morecomplex than in annelids. Arthropods have more developed nervetissue and sensory organs such as eyes.The exoskeletons of arthropods provide protection for theirsoft bodies. The circular muscles of annelids do not exist inarthropods. Muscles in arthropods are arranged in bands. Themuscles are associated with particular segments and appendages.Because arthropods have many hard parts, much is known abouttheir evolutionary history. Trilobites were once an importantgroup of ancient arthropods, but they have been extinct for 248million years.________________________________________________◗ After You ReadMini Glossarychelicerae (chih LIH suh ree): first pair of anarachnid’s six pair of appendages; locatednear the mouth, they are often modifiedinto pincers or fangslarva: in insects, the free-living, wormlike stageof metamorphosis, often called a caterpillarthe same general appearance as the adultinsect but is smaller and sexually immaturepedipalps (PE dih palpz): second pair of an arachnid’s six pair of appendages that are oftenadapted for handling food and sensingmetamorphosis (met uh MOR fuh sus): in insects,a series of chemically-controlled changes inbody structure from juvenile to adultpupa (PYEW puh): stage of insect metamorphosis where tissues and organs are brokendown and replaced by adult tissues; larvaemerges from pupa as mature adultnymph: stage of incomplete metamorphosiswhere an insect hatching from an egg hasspinnerets: glands that spin silk into thread,located at the rear of a spider1.
Read the terms and definitions in the Mini Glossary above. Circle three terms that relate tometamorphosis. Then, choose one of these terms and use it correctly in a sentence.__________________________________________________________________________________________________________________________________________________________________________________________________________________________________________READING ESSENTIALSChapter 28349NameDateClassSection28.2Diversity of Arthropods, continued2. Fill in the blanks below to list the stages of metamorphosis.MetamorphosisIncompleteCompleteegg➞➞➞➞➞adult3.
Write on the lines below, the stage at which molting occurs.Incomplete metamorphosis: ________________________________________________________________Complete metamorphosis:__________________________________________________________________Copyright © by Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.Visit the Glencoe Science Web site at science.glencoe.com to findyour biology book and learn more about diversity of arthropods.350Chapter 28READING ESSENTIALSNameDateClassSection29.1 EchinodermsSC.F.1.4.2 The student knows that body structures are uniquely designed and adapted for their function. SC.G.1.4.1The student knows of the great diversity and interdependence of living things. Also covers SC.F.1.4.7◗ Before You ReadHave you ever seen a sea star, a sea urchin, or a sand dollar? What do you know about them? Writetwo questions you have about them on the lines below.
Answer the questions after you have completed the Read to Learn section.________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________◗ Read to LearnCopyright © by Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.What is an echinoderm?Echinoderms belong to the phylum Echinodermata.Echinoderms (ih KI nuh durmz), which means spiny skinned,can be found in oceans all over the world.
Echinoderms moveusing hundreds of suction-cup-tipped appendages. The skin ofan echinoderm is covered with tiny, jawlike pincers. These characteristics distinguish echinoderms from other animals.What kinds of skeletons do echinoderms have?Echinoderms have hard, spiny, or bumpy endoskeletons. Anendoskeleton is an internal skeleton. The skeleton of all echinoderms is mostly calcium carbonate, the compound that makes uplimestone. A thin epidermis, or outer layer of skin, covers theendoskeleton. A sea urchin has long, pointed spines. Sea stars,sometimes called starfishes, may not look spiny, but they are. Ifyou look closely at a sea star, you will see that its long arms arecovered with short, rounded spines.
![](https://s.studizba.com/z.php?f=/templates/si/i/noavatar.png&w=100&h=100&t=1"){kind=avatar}
