Biology - Animals Vertebrates - Quick Guides

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Study GuideBiology–Animals: Vertebrates1. VertebratesAnimals can be grouped in a simple way based on one key feature: whether or not they have abackbone. Using this idea, scientists divide all animals intoinvertebratesandvertebrates.1.1 Invertebrates vs. Vertebrates•Invertebratesare animalswithout a backbone.•Vertebratesare animalswith a backbone.Most animals on Earth are invertebrates. They appear inevery major animal group, including alarge group called theChordata.1.2 What Is the Phylum Chordata?Thephylum Chordataincludes animals that share three important features at some stage of theirlife:1.Anotochord(a flexible supporting rod)2.Ahollow nerve cord3.Gill slitsNot all chordates are vertebrates. However,vertebrates belong to this phylum.1.3 Vertebrates: The Subphylum VertebrataWithin the phylum Chordata, animals that develop a backbone are placed in a smaller group calledthesubphylum Vertebrata.•There aremore than 40,000 living vertebrate species.•Vertebrates include thelargest animals ever to live on Earth.

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Study Guide○Dinosaurs were vertebrates.○Theblue whale, the largest animal alive today, is also a vertebrate.1.4 Major Groups of VertebratesVertebrates are divided into several major classes. These include:•Fishes•Amphibians•Reptiles•Birds•MammalsEach group has its own unique traits, but all share the defining feature of a backbone.2. Quiz Animals Vertebrates1. QuestionHow many living species of vertebrates are there?Answer Choices•120,000•200,000•60,000Correct Answer60,000Why This Is Correct

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Study GuideScientists estimate that there are about60,000 living species of vertebrateson Earth today. Theseinclude fish, amphibians, reptiles, birds, and mammals. This number reflects currently known andclassified species.3. FishesFishes are animals that live in water. Their bodies arestreamlined, which means they are shaped toreduce resistance as they swim. Most fishes also have astrong, functional tail, helping them movequickly and smoothly through water.To breathe, fishes usually usegills, which allow them to take oxygen from water. A few species alsohavelungsthat work alongside gills, giving them extra help with breathing.3.1Jawless Fishes: AgnathaOne group of fishes is calledAgnatha, which means “without jaws.”•These fishesdo not have jaws.•Examples includelampreysandhagfishes.•They feed in a unique way bysucking blood and other body fluidsfrom their prey, usuallyother fishes.These jawless fishes represent some of the simplest fish body plans still alive today.

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Study Guide3.2Early Jawed Fishes: Placodermi (Extinct)Another group of fishes is thePlacodermi.•Placoderms areextinct, meaning they no longer exist.•They are important because they were theearliest known fishes with jaws.•They lived mostly infreshwaterand stayed near the bottom.•Their bodies had apartly bony internal skeletonandhard, armored plateson the outside.Placoderms helped set the stage for more advanced fishes that came later.3.3Cartilaginous Fishes: ChondrichthyesThe classChondrichthyesincludes fishes with skeletons made entirely ofcartilage, not bone.•This group includessharks, skates, and rays.•They breathe through severalvertical gill openingslocated on both sides of the throat.•Cartilage makes their bodies lighter andmore flexible than those with bony skeletons.3.4Bony Fishes: OsteichthyesMost fishes we recognize today belong to the classOsteichthyes, orbony fishes.

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Study Guide•They havebony skeletons.•They live in bothsaltwater(such as tuna, mackerel, and herring) andfreshwater(such astrout, striped bass, and goldfish).•Bony fishes became especially successful during theDevonian Period, often called theAgeof Fishes.These fishes have:•Gillsfor breathing•Fleshy pectoral and pelvic finsfor movement and balance3.5Ray-Finned Fishes and the Swim BladderThe most common bony fishes today areray-finned fishes.•They have a special organ called aswim bladder.•The swim bladder is agas-filled sacnear the gut.•It helps the fishcontrol buoyancy, allowing it to float at different depths without much effort.4. Quiz Fishes1.QuestionWhat trait defines the class of fish calledAgnatha?Answer Choices•bony•jawless•lungsCorrect Answerjawless

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Study GuideWhy This Is CorrectThe classAgnathaincludes fish thatdo not have jaws. In fact, the wordAgnathaliterally means“without jaws.” These fish also lack paired fins and include animals such as lampreys and hagfish.2.QuestionWhat trait defines the class of fish calledChondrichthyes?Answer Choices•armored plates•cartilaginous•swim bladderCorrect AnswercartilaginousWhy This Is CorrectFish in the classChondrichthyeshave skeletons made ofcartilage rather than bone. This flexiblebut strongmaterial gives the group its name, which means “cartilage fish.” Sharks, rays, and skatesare examples of cartilaginous fish.3.QuestionWhat trait defines the class of fish calledOsteichthyes?Answer Choices•bony•cartilaginous•jawlessCorrect Answerbony

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Study GuideWhy This Is CorrectFish in the classOsteichthyeshavebony skeletons, which is the defining feature of this group. ThenameOsteichthyesmeans “bony fish.” Most modern fish, such as salmon and goldfish, belong to thisclass.5.AmphibiansAmphibians are special animals because they can liveboth in water and on land. Their namereflects this dual lifestyle. They belong to the classAmphibiaand play an important role in showinghow life first moved from water onto land.5.1 Where Amphibians Came FromScientists believe amphibians evolved fromlobe-finned fishesabout370 million years ago. Thistransition was important becauseair contains more oxygen than water, making breathing on landmore efficient.A key fossildiscovery helped explain this change.In 2006, scientists discovered a fossil calledTiktaalik. It is considered a remarkabletransitionalformbetween fish and early land animals (tetrapods).Tiktaalik showed a mix of features:•Like a fish, it hadfins and gills•Unlike most fish, it had aneck, shoulders, ribs, and fin bones arranged like a limb(humerus, radius, ulna, and wrist bones)These traits show the early steps toward animals walking on land.5.2 Modern AmphibiansToday, amphibians include:•Frogs•Toads

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