Chordates

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Chordates

• Cephalochordata
• Urochordata
• Agnatha
• Chondrichthyes
• Osteichthyes
• Amphibia
• Reptilia
• Aves
• Mammalia

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Chordate Origins

• Many studies suggest that the most ancient
  chordates were closely related to echinoderms

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What is a Chordate?

• 4 key characteristics present AT SOME TIME during
  an orgs lifetime.
• 1. dorsal, hollow nerve cord
• 2. notochord long, supportive rod, below
  nerve cord
• 3. pharyngeal pouches in neck or throat
  region
• 4. post-anal tail extends beyond anus

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Figure 34.2 Chordate characteristics
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Most Chordates are Vertebrates

• Vertebrate a chordate that has a strong
  supporting structure called the vertebral column
  or backbone which is made up of bony vertebrae
• In vertebrates, the dorsal, hollow nerve cord
  becomes the spinal cord
• Vertebrates have an endoskeleton which grows as
  the org grows, and is made up of living cells
  which produce non-living material

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Nonvertebrate Chordates

• Two Subphyla do NOT have backbones
• 1. Urochordata Tunicates
• filter feeders, larval form has chordate
  characteristics, adults do not
• 2. Cephalochordata Lancelets
• small, fish-like, live on sandy ocean bottom

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Figure 34.3 Subphylum Urochordata a tunicate
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Figure 34.4a Subphylum Cephalochordata lancelet
anatomy
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Figure 34.4b Subphylum Cephalochordata the
lancelet Branchiostoma
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7 Classes of Vertebrate ChordatesCh 30 - 32

• Agnatha jawless fish
• Chondrichthyes cartaligenous fish
• Osteichthyes bony fish
• Amphibia frogs, toads, mud puppies
• Reptilia snakes, lizards, turtles
• Aves birds
• Mammalia - mammals

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Evolutionary Trends in Vertebrates

• Adaptive Radiation
• Over the course of evolution, the appearance of
  new adaptations such as jaws and paired
  appendages has launched adaptive radiations in
  chordate groups
• Convergent evolution occurred many times during
  chordate evolution when unrelated species
  encountered similar ecological conditions and
  evolved similar adaptations

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Chordate Diversity
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Temperature Control in Chordates
Notice as the environment temperature changes, so
does the temperature for certain ectotherms
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The Digestive System of Chordates
WELL ADAPTED FOR A VARIETY OF FEEDING HABITS
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Chordate Respiration

• Aquatic chordates gills
• Land vertebrates - lungs

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Chordate Circulation

• Those that use gills for respiration have a
  single-loop circulatory system
• Blood travels from the heart to the gills, then
  to the rest of the body, and back to the heart in
  one circuit
• Those that use lungs for respiration have a
  double-loop circulatory system
• 1st loop carries blood between the heart and
  lungs, oxygen poor blood from the heart is pumped
  to the lungs, while oxygen rich blood from the
  lungs returns to the heart
• 2nd loop carries blood between the heart and the
  body oxygen rich blood from the heart is pumped
  to the body, while oxygen poor blood from the
  body returns to the heart

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Circulatory Systems of Vertebrates
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Chordate Hearts

• During the course of chordate evolution, the
  heart developed chambers and partitions that help
  separate oxygenated and deoxygenated blood
  traveling in the circulatory system
• Gilled vertebrates 2 chambered hearts
• Amphibians 3 chambered hearts
• Reptiles 3 chambered hearts with partitions
• Birds, mammals, crocodiles 4 chambered hearts
  that are completely partitioned

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Chordate Excretion

• Fishes and aquatic amphibians
• Excrete ammonia directly from gills via diffusion
• Mammals, land amphibians, and cartilaginous
  fishes
• Ammonia is changed into urea before excreted
  using kidneys
• Reptiles and birds
• Ammonia is changed into uric acid before excretion

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Chordate Response

• Nonvertebrate chordates have a relatively simple
  nervous system with a mass of nerve cells that
  form a brain
• Vertebrates have a more complex brain with
  distinct regions, each with a different function

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Chordate Movement

• Nonvertebrate chordates lack bones but have
  muscles for movement
• The skeletal and muscular systems support a
  vertebrates body and make it possible to control
  movement

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Chordate Reproduction

• Oviparous (eggs develop outside mothers body)
• Most fishes and amphibians
• Ovoviviparous (eggs develop within the mothers
  body)
• Sharks
• Viviparous (born alive)
• Most mammals

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Vertebrate Survey Lab 22

• Notes page for each Class complete with 2
  labeled and colored pictures
• Place in order from LEAST complex to MOST complex
• Staple question page to front may require you to
  use your text Ch 30-32 (tomorrow)
• Due day of Vertebrate Test