Lesson 19: Vertebrates I

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• Lesson 19 Vertebrates I
• Marine Biology

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Vertebrates Animals with a backbone

• Animals in the sub-phylum Vertebrata have spinal
  cords and brains
• Marine vertebrates include sharks, fish,
  turtles, birds, seals and whales
• Can you think of others?

Classification Overview Common Vertebrates Phylum
Subphylum Chordata
Vertebrata Classes Chondrichthyes Actinopterygii
Reptilia Mammalia
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Chondrichthyes Cartilaginous fishes

• Class Chondrichthyes means cartilaginous fish
  and consists of sharks, rays, skates and close
  relatives
• They share common features
• Jaws
• Cartilage skeletons, not true bone
• Fatty liver used for buoyancy
• Lack swim bladder
• Most have placoid scales
• They are great predators because they have
  pore-like structures near their snouts called
  ampullae of Lorenzini, which detect electrical
  currents of other organisms

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Some Chondrichthyes
Photo NOAA
Stingray They fly through the water using flat,
modified fins Order Rajiformes
Basking shark 2nd largest fish in the sea behind
the whale shark. It feeds on plankton Order
Lamniformes
Photo NOAA
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Agnatha The jawless fishes

• Superclass Agnatha Simple, more primitive fish
  that lack jaws
• Characteristics include
• No jaws
• Cartilaginous skeletons
• Lack scales, paired fins
• Long, eel-like
• Two class divisions
• Myxini (hagfish)
• Petromyzontida (lampreys)

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Some Agnathans
Photo NOAA
Photo NOAA
Sea Lamprey
Pacific hagfish off Oregon Coast
Fish with 2 sea lampreys attached
Photo NOAA
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Osteichthyes The bony fishes

• Superclass Osteichthyes contains the majority of
  the oceans fish
• Characteristics include
• Bone skeletons
• Operculum bony skin flap outside gills that
  helps fish breathe when not swimming
• Most use a swim bladder to keep them from sinking
• Two class divisions
• Actinopterygii (ray-finned fish including
  grouper, tuna and halibut)
• Sarcopterygii (lobe-finned fish including
  lungfish and coelacanths)

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Some Osteichtyhes
Photo SI
Photo NOAA
Indonesian coelacanth Lobe-finned fish
Yellowfin tuna Ray-finned fish
Walleye pollock Ray-finned fish
Photo NOAA
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Anatomy of a bony, ray-finned fish

• Fish use their fins to help them swim

dorsal fin
adipose fin
Photo NOAA
caudal fin
pectoral fin
pelvic fin
anal fin
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Class Reptilia Cold blooded animals

• Reptilians generally share these common features
• Cold-blooded they take on the temperature of
  their surroundings
• Breathe with lungs
• Reproduce by laying eggs

Classification Overview Common Reptilian
Orders Sub-Phlyum Class Vertebrata
Reptilia Orders Crocodilia Alligators
Crocodiles Chelonia Turtles,
Tortoises Squamata Snakes, Lizards
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Some marine reptiles

• Green sea turtle Order Testudines
• Sea turtles crawl onto the beach
• to lay their eggs
• When eggs hatch,babies must crawl to sea on the
  way they are highly vulnerable to seabirds and
  other predators

• Marine iguana Order Squamata
• These reptiles eat algae in cold
• water near the Galapagos Islands
• They warm themselves on rocks
• after their dives

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Managing fish populations

• Fishing contributes significantly to the U.S.
  economy and provides a vital food source
• Think back to the exercise at the beginning of
  class how did you estimate the number of fish in
  your container?
• Scientists use a combination of math, biology,
  and computer skills to best determine what levels
  of fishing can exist to provide food and support
  the economy without overfishing the resource
• NOAAs National Marine Fisheries Service works to
  sustainably manage our marine resources,
  including commercial fish populations, and to
  promote healthy ecosystems

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Fisheries management terminology

• A fish stock is group of individuals of the same
  species that inhabitat the same geographic region
  and interbreed when mature
• Single species may be made up of multiple stocks
  (each in a different geographic region), and
  fisheries are managed at the stock level
• An example of a stock is a group of salmon that
  always use and return to particular stream for
  reproduction. 
• Biomass (B) is the total weight of fish in a
  stock (e.g., metric tons)
• Fishing mortality rate (F) is the rate at which
  fishing removes fish from a stock

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Fisheries management terminology

• Sustainability represents the ability to persist
  in the long term
• If a fish stock remains at a constant level (or
  even grows) despite fishing pressure over a long
  time period, it is considered sustainable
• Maximum sustainable yield (MSY) is the greatest
  number of fish that can be caught each year
  without impacting the long-term productivity of
  the stock
• Overfishing occurs when fishing mortality exceeds
  a specific threshold, usually set at a level to
  achieve MSY
• A stock is considered overfished when the stock
  size falls below a specific threshold, either in
  terms of numbers or biomass

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Student activity

• In todays activity, we will discuss in more
  detail what it means to fish sustainably and
  you will evaluate sustainable seafood restaurants