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

NotochordDorsal hollow

nerve cordPharyngeal

gill slits/ pouchesPostanal

tail

Section 30-1

Muscle segments

TailAnus

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 chordates

Jawless fishes

Cartilaginous fishes

Bony fishes

Amphibians

Reptiles

Birds

Mammals

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 SubphylaChordate SubphylaPhylum. Chordata

Subphylum. Urochordata

Subphylum. Cephalochordata

Subphylum. Vertebrata

Phylum. ChordataSubphylum. Urochordata

Subphylum. Cephalochordata

Subphylum. 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.wordpress.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:

• Closed circulatory system• Bilateral symmetry• True coelom• 3 germ layers• Endoskeleton- backbone• Sexual reproduction- internal or external

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)

Bo

dy

Tem

per

atu

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 Animalia

Phylum Chordata

Subphylum Vertebrata

Class Agnatha

“Jawless” Fish (most primitive): Traits:

-Sucker like mouth(no jaws)

-No fins or paired appendages

-Cartilage skeleton w/ notochord

Ex: lamprey & hagfish

Kingdom Animalia

Phylum Chordata

Subphylum Vertebrata

Class Chondrichthyes-Cartilage Fish

Traits:

Cartilage skeleton; 2 chambered heart

Lateral line system –detect vibrations (movement & sense)

Paired appendages- pectoral and pelvic girdles

Poor eyesight, great olfactory

Carnivorous or scavenger, no swim bladder

Ex: sharks, skates, rays

Fish Scales Scales Tails

Tails

Sharks and rays

lungfish Bony fish

Fish Tail Cladogram

Kingdom Animalia

Phylum Chordata

Class Osteichthyes-

Bony Fish

Traits:

Bony skeleton; 2 chambered heart

Lateral line system/movement & sense

Swim bladder-control depth (buoyancy)

Have operculum over gills

Good smell (olfactory) and eyesight

Ex: perch, bass, flounder