Figure 8.01

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Figure 8.01
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Characteristics of Subphylum Vertebrata

• A notochord that has developed into a spinal cord
  protected by vertebrae. Also contain a head with
  a brain.

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• Significance of Class Agnatha
• This is the class of the jawless fish.
• Species include lampreys and hagfish.
• Organisms in this class are significant because
  they may represent the ancestor of bony
  fish/sharks.
• Scientists theorize that during the Cambrian
  period the first of three gill arches on a
  jawless fish evolved into the first jaws.
• Having jaws allowed vertebrates to become very
  successful predators.
• Having jaws put organisms in class Chondrichthyes
  (sharks and rays) and class Osteichthyes (bony
  fish) near the top of marine food webs.

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Figure 8.02
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Characteristics of Sharks and Rays

• Class Chondrichthyes includes sharks, rays and
  their close relatives.
• Sharks and rays dont look similar on the
  outside, butshare a basic anatomy that
  classifies them together.
• Sharks and rays are jawed fish, that lack a swim
  bladder, and have cartilaginous skeletons.

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• Special Attributes of Sharks and Rays
• Sharks and rays are successful predators
• They have cartilaginous skeletons.
• This characteristic saves energy. Saving energy
  is one of thethings that have made them
  successful predators.
• Sharks have a sense of smell that detect
  incrediblydiluted substances. (one drop of
  blood in a mile of water)
• Sharks have a conveyor belt of multiple rows of
  teeth.
• They swing into place as old teeth wear out and
  fall away.

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Special Attributes of Sharks and Rays

• Sharks and rays have other interesting
  characteristics
• Both have lateral lines lines of sensory organs
  along the length of the body that detect water
  motion and vibrations.
• Unique to sharks and rays is electroreception
  the ability to sense minute electricity created
  by muscles and nerves.
• Sharks and rays have organs called ampullae of
  Lorenzini which you can see as visible pits near
  their snouts used to detect the electrical
  current.

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Special Attributes of Sharks and Rays

• New type of reproductive strategy.
• Sharks and rays produce fewer, but more mature
  offspring.
• Most fertilize their eggs internally.
• A few shark species are ovoviviparous the eggs
  hatch within the mothers body.
• They give birth to live young rather than egg
  cases.

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• The largest fish in the ocean.
• Shark size ranges from hand-sized to thewhale
  shark the largest fish in the ocean.
• Whale sharks can reach 14 meters (46 feet).
• Basking sharks can reach 10 meters (33 feet).
• Megamouth sharks can reach 6 meters (20 feet).
• All three are filter feeders that consume
  plankton.

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Visiting The Georgia Aquarium!
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Figure 8.14a
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Special Attributes of Rays

• Superorder Batidoidimorpha of subclass
  Elasmobranchii consists of therays, which
  includes skates and guitarfish.
• Ray anatomy is well suited to life on sandy
  bottoms or midwater.
• Specially adapted to life in midwater are the
  eagle ray and manta ray.
• Pectoral fins have become wings that stretch
  forward over the gills and are fused to the
  sides of the head.
• Shoulder girdles are flattened and many bones
  are fused together for rigidity.
• No longer need a tail for swimming, the tail has
  become a defensive whip in some species.
• Rays literally fly through the water.
• The largest rays are mantas with wingspans
  exceeding 8 meters (26 feet).
• Like the largest shark, the mantas feed on
  plankton.

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Figure 8.12a
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Figure 8.26
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Figure 8.04
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Figure 8.05b
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Figure 8.06b
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Figure 8.07
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Figure 8.08a