chordates - sommascience.weebly.com€¦ · classification of the chordates the chordates are...

Chordates Name: _________________________________________ Class:__________ Date: ____________ Vocabulary Term Definition chordate Animal with a notochord, dorsal hollow nerve cord, post-anal tail, and pharyngeal slits during at least some stage of its life. dorsal hollow nerve cord Hollow cord above the notochord; sometimes includes a brain and spinal cord. notochord Support rod that runs along the back. pharyngeal slit Organ that aids in filter-feeding. post-anal tail Tail that is opposite the head and extends past the anus. What do these two animals have in common with you? Notice the orange fish. Around him is another type of animal, a tunicate, in blue. Tunicates, fish, and humans seem very different from one another, but they do have some things in common. They are all chordates. Chordates Did you know that fish, amphibians, reptiles, birds, and mammals are all related? They are all chordates. Chordates are a group of animals that includes vertebrates, as well as several closely related invertebrates. Chordates (phylum Chordata) are named after a feature they all share, a notochord. A notochord is a hollow nerve cord along the back. Characteristics of the Chordates Chordates are defined by a set of four characteristics that are shared by these animals at some point during their development. In some chordates, all four traits are present in the adult animal and serve important functions. However, in many chordates, including humans, some traits are present only during the embryonic stage. After that, these traits may disappear. All chordates have four main traits: 1. Post-anal tail: The tail is opposite the head and extends past the anus. 2. Dorsal hollow nerve cord: "Dorsal" means that the nerve cord runs along the top of the animal. In some animals, the nerve cord develops into the brain and spinal cord. 3. Notochord: The notochord lies below the nerve cord. It is a rigid structure where muscles attach. 4. Pharyngeal slits: Pharyngeal slits are used to filter out food from water by some simple chordates. In most chordates, however, they are only present during the embryonic stages and serve no apparent purpose. Classification of the Chordates The chordates are divided into nine classes. Five of the classes are the fish, amphibians, reptiles, birds, and mammals. There are actually five classes of marine chordates (for example, sharks are cartilaginous fish which are distinct from bony fish), and these will be discussed in additional concepts. The chordate phylum is broken down into three subphyla: • Urochordata: The tunicates, pictured in the introduction, make up this group. The urochordates are sessile (non-moving) marine animals with sack-like bodies and tubes for water movement. Urochordates have a notochord and nerve cord only during the larval stage.

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Page 1: Chordates - sommascience.weebly.com€¦ · Classification of the Chordates The chordates are divided into nine classes. Five of the classes are the fish, amphibians, reptiles, birds,

Chordates Name:_________________________________________Class:__________Date:____________Vocabulary

Term Definition

chordate Animalwithanotochord,dorsalhollownervecord,post-analtail,andpharyngealslitsduringatleastsomestageofitslife.

dorsal hollow nerve cord Hollowcordabovethenotochord;sometimesincludesabrainandspinalcord.

notochord Supportrodthatrunsalongtheback.pharyngeal slit Organthataidsinfilter-feeding.post-anal tail Tailthatisoppositetheheadandextendspasttheanus.

What do these two animals have in common with you? Noticetheorangefish.Aroundhimisanothertypeofanimal,atunicate,inblue.Tunicates,fish,andhumansseemverydifferentfromoneanother,buttheydohavesomethingsincommon.Theyareallchordates.Chordates Didyouknowthatfish,amphibians,reptiles,birds,andmammalsareallrelated?

Theyareallchordates.Chordatesareagroupofanimalsthatincludesvertebrates,aswellasseveralcloselyrelatedinvertebrates.Chordates(phylumChordata)arenamedafterafeaturetheyallshare,anotochord.Anotochordisahollownervecordalongtheback.Characteristics of the Chordates Chordatesaredefinedbyasetoffourcharacteristicsthataresharedbytheseanimalsatsomepointduringtheirdevelopment.Insomechordates,allfourtraitsarepresentintheadultanimalandserveimportantfunctions.However,inmanychordates,includinghumans,sometraitsarepresentonlyduringtheembryonicstage.Afterthat,thesetraitsmaydisappear.Allchordateshavefourmaintraits:

1. Post-analtail:Thetailisoppositetheheadandextendspasttheanus.2. Dorsalhollownervecord:"Dorsal"meansthatthenerve

cordrunsalongthetopoftheanimal.Insomeanimals,thenervecorddevelopsintothebrainandspinalcord.

3. Notochord:Thenotochordliesbelowthenervecord.Itisarigidstructurewheremusclesattach.

4. Pharyngealslits:Pharyngealslitsareusedtofilteroutfoodfromwaterbysomesimplechordates.Inmostchordates,however,theyareonlypresentduringtheembryonicstagesandservenoapparentpurpose.

Classification of the Chordates Thechordatesaredividedintonineclasses.Fiveoftheclassesarethefish,amphibians,reptiles,birds,andmammals.Thereareactuallyfiveclassesofmarinechordates(forexample,sharksarecartilaginousfishwhicharedistinctfrombonyfish),andthesewillbediscussedinadditionalconcepts.Thechordatephylumisbrokendownintothreesubphyla:

• Urochordata:Thetunicates,picturedintheintroduction,makeupthisgroup.Theurochordatesaresessile(non-moving)marineanimalswithsack-likebodiesandtubesforwatermovement.Urochordateshaveanotochordandnervecordonlyduringthelarvalstage.

Page 2: Chordates - sommascience.weebly.com€¦ · Classification of the Chordates The chordates are divided into nine classes. Five of the classes are the fish, amphibians, reptiles, birds,

• Cephalochordata:Cephalochordatesincludethelancelets,fish-likemarineanimalsoftenfoundhalf-buriedinthesand.Cephalochordateshaveanotochordandnervecordbutnobackbone.

• Vertebrata:Humansandothermammals,alongwithfish,amphibians,reptiles,andbirds,fallinthiscategory.Invertebrates,thenotochordistypicallysmallerandsurroundedbyabackbone.

Summary

• Chordatesareanimalsthathaveanotochord,post-analtail,dorsalhollownervecord,andpharyngealslits.

• Chordatesincludeallvertebratesandsomeinvertebrates. Review

1. Whatisthemaincommonfeatureofallchordates?

2. Nameanddescribethreeexamplesofchordates.

3. Listandexplainthreecharacteristicsofchordates.

4. Whatisthedorsalhollownervecord?

Chordates 1. Chordate Taxonomy Chordates: 1.Single dorsal hollow nerve cord 2.Gill slits 3.Notochord

Intro to Chordates p. 270-274

Chordates: Phylum Chordata

CHORDATES ( 脊索动物门）

Invertebrate Chordates - BIOLOGY 11 - Homeaa-vlacil-bio11.weebly.com/uploads/2/3/0/7/23071266/27.2...Section 2 • Invertebrate Chordates 803 Chordates are animal s belonging to the