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Chordates
An 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 “musclelike” for burrowing
C-Vertebrata- Notochord becomes
backbone. 7 Classes
Section 33-1
Concept Map
Chordates
have the following
key features
Notochord
which is
Dorsal hollow
nerve cord
Postanal
tail
Pharyngeal
gill slits/ pouches
The Generalized Structure of a Chordate:
Section 30-1
A flexible
supporting
structure
We even start out this way in the womb!
Notochord
Muscle segments
Tail
Hollow
nerve cord
Anus
Mouth
Pharyngeal pouches
Chordates
4
Phylum Chordata
5
Phylum Chordata
• Notochord
• Gill slits or
pharyngeal
pouches
• Dorsal hollow
nerve cord
• Postanal tail
• Segmented
muscles
• Deuterostome
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7
8
9
10
Evolutionary Adaptations of Chordates
• From filter feeding
ancestors to active
predators
–
–
–
–
–
Mobility
Oxygen capture
Digestion
Circulation
Nervous system
11
Skeletal Changes
• Skeleton becomes
stronger to work with
bigger muscles
• Allows more rapid
movement
12
Oxygen Capture
• Gill slit and muscular
pharynx will move more
water over gills
– More oxygen is extracted
from water
13
Circulation
• Stronger heart to
circulate blood faster
14
Digestion
• Digest more food
– Muscularized gut
– Digestive glands
• Liver
• Pancreas
15
Nervous System
• More complex for better
– Motor control of body to
capture food
– Sensory detection of the
animals environment
– Integration centers
(brain)
16
Brain With Three Parts
Hindbrain
Midbrain
Forebrain
17
Section 33-1
Nonvertebrate chordates
Jawless fishes
Cartilaginous fishes
Bony fishes
Amphibians
Reptiles
Birds
Mammals
Figure 33–2 A Cladogram of
Chordates
Chordate Cladogram
Mammals
Birds
Amphibians
Fishes
Nonvertebrate
chordates
Invertebrate ancestor
Reptiles
Figure 33–4 Diversity of Chordates
Section 33-1
Nonvertebrate chordates
(4%)
Mammals
(8%)
Birds
(18%)
Reptiles
(14%)
Amphibians
(9%)
Fishes
(47%)
Chordate Subphyla
Phylum.
Chordata
Urochordata
Subphylum. Cephalochordata
Subphylum. Vertebrata
Subphylum.
21
Sea Squirts
22
Subphylum Urochordata
• Sea squirts (aka tunicate)
• Gill slits (pharyngeal slits)
• Notochord
– Only in larva
• Adult has tunic- made of
cellulose, sessile
• http://www.arkive.org/starascidian/botryllusschlosseri/
• http://finstofeet.wordpress.c
om/2010/03/14/1-2-behold-
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Subphylum Cephalochordata
• Amphioxus (lancelets)
• Notochord length of
body
• Dorsal hollow nerve
cord
• Gill slits
• Segmented muscles
• Maintain all chordate
characteristics as adult
27
Amphioxus
28
Amphioxus
29
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
Temperature Control in
Chordates
Body Temperature (°C)
Section 33-2
Environmental Temperature (°C)
98.6 F- avg human temp
How vertebrates maintain their temperature
Animal Group
Endo/ectotherm
Behavior/structure
Fish
Ectotherm
Swim bladder:
Cold/move up
Hot/move down
Amphibian
Ectotherm
Cool/go in sun
Hot/go to water
Reptile
Ectotherm
Cool/bask
Hot/go to water
Birds
Endotherm
Cool/fluff feather
Hot/raise wings
Mammals
Endotherm
Sweat, pant,
shiver
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
http://missbakersbiologyclass.com/blog/2009/
04/06/dogfish-shark-dissection-includesvideo/
Fish Scales
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