ChordatesAn Introduction

Kingdom Animalia- All inverts & verts

1. Phylum Chordata: All have nerve cords. 3 subphyla :

A- Urochordata (tunicates aka sea squirts). Only larvae have notochord

B-Cephalochordata (lancelets aka Amphioxus). Retain notochord throughout adulthood, but “muscle- like” for burrowing

C-Vertebrata- Notochord becomes backbone. 7 Classes

Section 33-1

have the followingkey features

which is

Concept MapChordates

A flexiblesupportingstructure

Notochord Dorsal hollownerve cord

Pharyngealgill slits/ pouches

Postanal tail

Section 30-1

Muscle segments

Tail Anus

Pharyngeal pouches

Mouth

Hollownerve cord

Notochord

The Generalized Structure of a Chordate:

We even start out this way in the womb!

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Chordates

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Phylum Chordata

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Phylum Chordata• Notochord• Gill slits or

pharyngeal pouches

• Dorsal hollow nerve cord

• Postanal tail• Segmented

muscles• Deuterostome

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Evolutionary Adaptations of Chordates

• From filter feeding ancestors to active predators– Mobility– Oxygen capture– Digestion– Circulation– Nervous system

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Skeletal Changes• Skeleton becomes

stronger to work with bigger muscles

• Allows more rapid movement

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Oxygen Capture• Gill slit and muscular

pharynx will move more water over gills– More oxygen is extracted

from water

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Circulation• Stronger heart to

circulate blood faster

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Digestion• Digest more food

– Muscularized gut – Digestive glands

• Liver• Pancreas

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Nervous System• More complex for better

– Motor control of body to capture food

– Sensory detection of the animals environment

– Integration centers (brain)

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Brain With Three Parts

ForebrainMidbrainHindbrain

Section 33-1

Nonvertebrate chordatesJawless fishesCartilaginous fishesBony fishesAmphibiansReptilesBirdsMammals

Figure 33–2 A Cladogram of Chordates

MammalsBirds

ReptilesAmphibians

Fishes

Nonvertebratechordates

Invertebrate ancestor

Chordate Cladogram

Section 33-1

Fishes(47%)

Nonvertebrate chordates(4%)

Mammals(8%)

Birds(18%)

Reptiles(14%)

Amphibians(9%)

Figure 33–4 Diversity of Chordates

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Chordate SubphylaPhylum. Chordata

Subphylum. UrochordataSubphylum. CephalochordataSubphylum. Vertebrata

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Sea Squirts

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Subphylum Urochordata• Sea squirts• Gill slits (pharyngeal

slits)• Notochord

– Only in larva• Adult has tunic- made

of cellulose, sessile• http://finstofeet.wordpre

ss.com/2010/03/14/1-2-behold-the-tunicates/

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Subphylum Cephalochordata• Amphioxus• Notochord length of

body• Dorsal hollow nerve

cord• Gill slits• Segmented muscles• Maintain all chordate

characteristics as adult

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Amphioxus

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Amphioxus

Subphylum Vertebrata: All Vertebrates have:

• Endoskeleton- backbone• Closed circulatory system• Bilateral symmetry• True coelom• Sexual reproduction- internal or external

Vertebrate Groups- Fish, Amphibians, Reptiles, Birds, and Mammals

Homeostasis

• Endothermic (warm-blooded)- internal temp. regulation that must be maintained

Ex. Birds & Mammals

• Ectothermic (cold-blooded)- external temp. regulation/ regulated by environment

Ex. Nonvertebrate chordates, Fish, Amphibians, Reptiles

Section 33-2

Environmental Temperature (°C)

Bod

y Te

mpe

ratu

re (°

C)

Temperature Control in Chordates

98.6 F- avg human temp

Animal Group Endo/ectotherm Behavior/structure

Fish Ectotherm Swim bladder:Cold/move upHot/move down

Amphibian Ectotherm Cool/go in sunHot/go to water

Reptile Ectotherm Cool/baskHot/go to water

Birds Endotherm Cool/fluff featherHot/raise wings

Mammals Endotherm Sweat, pant, shiver

How vertebrates maintain their temperature

Kingdom AnimaliaPhylum ChordataSubphylum VertebrataClass Agnatha “Jawless” Fish (most primitive): Traits:-Sucker like mouth(no jaws)-No fins or paired appendages-Cartilage skeleton w/ notochordEx: lamprey & hagfish

Kingdom AnimaliaPhylum Chordata Subphylum VertebrataClass Chondrichthyes-Cartilage FishTraits:Cartilage skeleton; 2 chambered heartLateral line system –detect vibrations (movement & sense)Paired appendages- pectoral and pelvic girdlesPoor eyesight, great olfactoryCarnivorous or scavenger, no swim bladder Ex: sharks, skates, rays

Fish Scales

Tails

Sharks and rays

lungfish Bony fish

Fish Tail Cladogram

Kingdom AnimaliaPhylum ChordataClass Osteichthyes-Bony FishTraits:Bony skeleton; 2 chambered heartLateral line system/movement &

senseSwim bladder-control depth

(buoyancy)Have operculum over gillsGood smell (olfactory) and eyesightEx: perch, bass, flounder