Chordates, Vertebrates, and agnatha

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Chordates, Vertebrates, and agnatha

• By Sabena Suri

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Chordates

• What is a chordate?
• A chordate is a member of the Phylum (remember-
  just under Kingdom) Chordata
• These animals, at some point, have
• a developmental dorsal hollow nerve chord
• a notochord
• pharyngeal slits
• a post-anal tail
• Under the Phylum Chordata, there are the
  organisms lancelets, tunicates, and vertebrates

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Chordates, continued

• So, there are two kinds of Chordates
• Invertebrate Chordates they do not have a
  vertebral column. They are usually marine
  animals. The two groups are lancelets and
  tunicates.
• Lancelets
• Tunicates
• Vertebrate Chordates they have a vertebral
  column, so they enclose the main parts of the
  nervous system. The skeleton is an endoskeleton,
  made of either flexible cartilage or a
  combination of hard bone and cartilagecan grow
  with the animal.
• Tetrapods first vertebrates on land
• Amniotes tetrapods with a terrestrially adapted
  egg, which allowed for enhanced reproduction on
  land

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Agnatha

• Agnatha- these are also under the Vertebrate
  category of Chordates
• They are jawless vertebrates that wrap around
  their prey to eat the food
• Lamprey is an example of an Agnatha they are
  jawless fish

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Development of Hinged Jaw

• Eventually, a hinge jaw developed in animals like
  sharks, fishes, amphibians, reptiles (including
  birds), and mammals
• The jaw was supported by two skeletal parts held
  together by a hinge- it came to be because of a
  modification of skeletal supports of the anterior
  gill slits

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Hinged Jaw, Continued

• The hinged jaw allows for better ingestion of
  prey, as shown below
• Since humans are in the vertebrate category of
  the Phylum Chordata, it is important to note the
  specific characteristics of vertebrates so we can
  understand more about the biology of humans
• Questions?

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Sources

• http//biodidac.bio.uottawa.ca/ftp/BIODIDAC/ZOO/VE
  RTEBRA/DIAGBW/AGNA004B.GIF
• http//en.wikipedia.org/wiki/Agnatha
• http//lotusart.de/stills/Snake.jpg
• Our textbook