Transcript Chordata

Chordata
http://www.devonianlife.com/Pteraspis.jpg
By
Nicko and Cecil
Phylum:
• Chordates - Bilaterian (bilaterally
symmetrical) animals.
• All chordates share a notocord, a dorsel,
hollow nerve cord, pharyngeal slits of
clefts and a muscular post-anal tail at one
point in their lifetime (may only be in
embyronic development).
• There are eleven major groups of
chordates but six groups of fish.
Sample Animals
• Six major groups of fish.
– Myxini (hagfish)
– Cephalaspidomorphi (lampreys)
– Chondrichthyes (sharks and rays)
– Actinopterygii (ray-finned fishes)
– Actinistia (coelacanths)
– Dipnoi (lungfishes)
Myxini
(hagfish):
• The only fish that still survives from this
group are hagfishes.
• Skulls made of cartilage and lack jaws and
vertebrae.
• Small brain, eyes, ears and nasal
openings that connects with the
pharynx, and slime
glands.
• Bottom dwelling
scavengers.
http://jomacdoom.files.wordpress.com/2009/08/hagfish.jpg
Cephalaspidomorphi
(lampreys)
• Oldest living lineage of vertebraes.
• The skeleton is made of cartilage that
contains no collagen and they lack jaws.
• Most are parasitic feeders.
http://people.cornellcollege.edu/b-hess/geo105/images/lamprey.jpg
Chondrichthyes
(sharks and rays)
• Most successful vertebrae predators in the
ocean.
• Have a skeleton composed predominantly of
cartilage often impregnated with calcium.
• Lay eggs that hatch outside the mothers body.
• Larger sharks and rays are suspension feeders.
• Most sharks are carnivores.
http://www.itsallaboutfish.co.uk/Pictures/Manta%20rays.jpg
http://templecuttingedge.files.wordpress.com/2009/06/great-white-shark-1.jpg
Actinopterygii
(ray-finned fishes)
• Most fish familiar to us belong to this
phylum.
• The fins are modified for maneuvering,
defense and other functions.
• Some species include bass, trout, herring,
etc.
http://bss.sfsu.edu/holzman/courses/Fall01%20projects/rainbowtrout%20fig2.jpg
Actinistia
(coelacanths)
• Lobe-finned fish.
• Thought to be extinct until 1938 when
fisherman discovered in West Indian
Ocean.
http://www.foxnews.com/images/302823/0_61_070731_coelacanth.jpg
Dipnoi
(lungfishes)
• The second lineage of living lobe-fins.
• All are found in the Southern Hemisphere.
• Only found in fresh water, generally in
stagnant ponds and swamps.
• Can gather oxygen from both the air
through their pharynx
and the water through
their gills.
http://www.mongabay.com/images/calacademy/600/lungfish_going_left.jpg
Body Cavity/Symmetry
• Three distinctive characteristics that make
chordata unique:
– Notochord.
– Hollow nerve cord that lies dorsal to the
notochord.
– Pharyngeal pouches.
• All chordates have a coelom.
• Most chordates have bilateral symmetry.
Nervous System
• Has a brain and a central nervous system.
• Have a lateral line system that helps them
detect prey.
• The hollow nerve cord is what develops
into the spine
http://library.thinkquest.org/C0124402/data/images/2/2skeleton.gif
Other Body Systems
• Circulatory System
– Cold blooded.
– Contains a heart, blood and blood vessels.
• Digestive System
– Eats algae and plants/animals.
– Those that eat animals have teeth.
• Excretory System
– A fish gets rid of waste through the anus.
Locomotion/Musculature
•The notochord not only provides support, but is
also a key element muscles use during swimming
•All chordates have post-anal tails, however some
are lost during embryonic development
•Many fish use these tails, which move in a
vacillating motion, as the main force that propels
them through the water
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http://kentsimmons.uwinnipeg.ca/16cm05/16labman05/lb7pg1_files/34-02-ChordateCharacters-L.gif
Skeletal Type
•The notochord is a long flexible composed of
fluid filled cells encased by fibrous tissue is
located between the digestive tube and the
nerve cord
•However, many species can also lose the
notochord in embryonic development
•As a result, a much more complex joint skeleton
forms
•Only ray-finned and lobe-finned skeletons are
not composed primarily of cartilage
•Ray-finned and lobe-finned fish contain bones
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made of calcium phosphate
Sensory structures/features
• Have eyes, but no eyelids
• Retinas contain both and cones and pupils
let in a great deal of light
• Have nasal passages that connect with
the pharynx
• Some fish have a nasal sac that also
connects to the nasal passage that
improves their sense of smell
• Have inner ears, but no outer ear opening
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Reproduction Methods
• Reproduce sexually
• Female lays her eggs
• Male comes and fertilizes the eggs
(sprays a substance called milt, which
contains sperm)
• However, some females carry their eggs
until birth
• Egg contains a yolk that nourishes the fish
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Gas Exchange
• Acquire oxygen and release acrbon
dioxide through pharyngeal slits (gills)
• Pharyngeal slits are composed of
threadlike filaments
• When water passes through the
pharyngeal slits, the blood vessels within
the filaments absorb oxygen and release
carbon dioxide
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Other Unique features
• Chordates are the only animals with hollow
nerve cords
• All other animals have solid nerve cords
• Ray-finned fish were the first animals to have
bones composed of calcium carbonate
• Conodonts were the first animals to have
mineralized mouth parts
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http://www.earthlife.net/fish/skeleton.html
Quiz
What is a feature that is not unique to
chordates?
a) Notochord
b) A hollow nerve cord
c) Mineralized mouthpieces
d) Pharyngeal slits
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Quiz
True or False:
All fish have bones composed of calcium
carbonate
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Quiz
Which part of the circulatory system do fish
not have?
a) Blood
b) Blood vessels
c) Heart
d) They have all of the above
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Quiz
True or False:
Sharks bones and teeth are made primarily
out of cartilage
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