Chapter 25: Vertebrate Diversity

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Chapter 25 Vertebrate Diversity
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25.1 Vertebrate Origins

• 25.1 Vertebrate Origins
• Words to Know Chordate, Notochord, Endoskeleton

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Phylum Chordata

• The phylum Chordata is made of three groups
  Urochordata, Cephalochordata, and Vertebrates
• Both Urochordates and Cephalochordates are
  invertebrates.
• Urochordates are Tunicates like sea squirts.
• Cephalochordates are Lancelets that spend most of
  their lives buried in the sand.
• Vertebrates are large, active animals that have a
  well-developed brain encased in a hard skull.
• ALL Chordates share the same four features at
  some stage in development
• Notochord a flexible skeletal support rod
  embedded in the animals back.
• Hollow Nerve Cord runs along the animals back.
• Pharyngeal Slits slits through the body wall in
  the pharynx, where water can enter the mouth and
  leave the animal through these slits without
  passing through the entire digestive system.
• Tail extends beyond the anal opening and
  contain muscles for movement.
• Most chordate groups lose some or all of these
  characteristics in adulthood, but they are
  present in the embryo.

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Phylum Chordata
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Vertebrate Common Features

• Endoskeletons
• An Endoskeleton is an internal skeleton built of
  bone or cartilage.
• Vertebrate endoskeletons can be divided into
  distinct parts.
• Braincase protects the brain.
• Vertebrae a series of short, stiff vertebrae
  are separated by joints and protect the spinal
  cord.
• Bones support and protect the bodys soft
  tissues and provide points for muscle attachment.
• Gill Arches found in fish and some amphibians
  help support the gills.
• Vertebrate endoskeletons can slowly change size
  and shape.

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Vertebrate Common Features

• Vertebrate Classes
• There are currently 7 classes of vertebrates
• Agnatha jawless fish including lampreys.
• Chondrichthyes cartilaginous fish that include
  sharks, rays, and chimeras.
• Osteichthyes bony fish that include ray-finned
  fish, trout, and goldfish.
• Amphibia first vertebrates adapted to land and
  include frogs, toads, salamanders, and
  caecilians.
• Reptilia can retain moisture and live
  exclusively on land. Include snakes, lizards,
  crocodiles, alligators and turtles.
• Aves Birds, animals with feathers and hollow
  bones.
• Mammals animals with fur, mammary glands, and
  three middle ear bones. Includes humans,
  elephants, kangaroos etc

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Vertebrate Classes
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Origins of Vertebrates

• Much of what we know comes from fossil evidence
  found in the Burgess Shale locates in the
  Canadian Rocky Mountains in the early 1900s.
• Many are dated around the Cambrian explosion.

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Closest Relatives

• Tunicates may actually be the closest relatives
  of vertebrates.
• Scientists have found that tunicates have cells
  that resemble the neural crest that is also found
  in vertebrates.

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Jawless Fish Early Vertebrates

• The first recognizable vertebrates were fish.
• The oldest fish fossils date back 530 million
  years.
• Early fish were small, jawless bottom-feeders.

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Lampreys

• There are more than 35 species of Lampreys.
• They are highly specialized fish parasites.
• Physical Characteristics include
• Long and slender body plans with NO paired fins.
• Mouths surrounded by large suckers.
• Tongues covered by tooth-like projections.
• The accidental introduction of sea lampreys into
  the Great Lakes in the early 1900s had a
  devastating effect on the fishing industry.

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Hagfish

• A jawless eel-like animal with a partials skull
  but NO vertebrae.
• It uses a notochord for support.

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25.2 Fish Diversity

• 25.2 Fish Diversity
• Words to Know Gill, Countercurrent Flow,
  Lateral Line, Operculum

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Fish

• Fish use specialized organs called gills to take
  in the oxygen dissolved in water.
• Gills are large sheets of thin frilly tissue
  filled with capillaries that take in dissolved
  oxygen from the water and release carbon dioxide.
• Fish circulatory systems pump blood in a single
  circulatory loop through a heart with two main
  chambers.

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Countercurrent Flow

• Countercurrent Flow is the opposite movement of
  water against the flow of blood in the fishs
  gills.
• Countercurrent flow maximizes the amount of
  oxygen the fish can pull from the water by
  diffusion.

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Swimming and Maneuvering

• Most fish swim by contracting large segmented
  muscles on either side of their vertebral column
  from the head to the tail.
• Fins help keep fish stable.

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Jaws

• Jaws evolved from gill arches.
• Gill arches are structures made of bone or
  cartilage that function as a support for fishs
  fills.
• Jaws developed from gill arches near the mouth,
  which fused to the cranium.
• Jaws gave vertebrates a huge advantage as
  predators and quickly pushed them to the top of
  the food chain.

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Two Groups of Jawed Fish

• Jawed fish diversified very quickly after their
  first appearance about 440 million years ago.
• Four groups appeared at this time
• Acanthodians were fish covered with spines and
  became extinct 250 million years ago.
• Placoderms were heavily armored with huge bony
  plates and became extinct 350 million years ago.
• Cartilaginous Fish Skeletons are made of
  cartilage and include sharks, rays and chimera.
• Bony Fish Include all other living fish

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Cartilagenous Fish (Chondrichthyes)

• Have skeletons made of cartilage.
• Their cartilage contains calcium deposits that
  make it stiffer than the squishy stuff around
  human joints.
• There are more than 300 species of shards and
  nearly 400 species of rays and skates.
• All are predators.
• Cartilaginous fish have internal fertilization
  and many give birth to live young.
• They are also powerful swimmers with good
  eyesight and an excellent sense of smell.
• All fish have a Lateral Line system, which is a
  series of shallow canals on the sides of the fish
  made up of cells that are sensitive to small
  changes in water movement.
• This give fish a sense of distant touch letting
  them sense movement in the water far away.

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Bony Fish (Osteichthyes)

• All other living fish have skeletons made of
  bone.
• There are more than 20,000 species of bony fish
  living in almost all aquatic environments.
• The gills of all bony fish are in a chamber
  covered by a protective plate called the
  operculum.
• This helps fish move water over their gills.

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25.3 A Closer Look at Bony Fish

• 25.3 A Closer Look at Bony Fish
• Words to Know Ray-fin, Swim Bladder, Lobe-fin

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Ray-finned Fish

• All ray-finned fish, such as goldfish and tuna,
  have fins supported by a fan shaped array of
  bones called a ray-fin.
• Ray-finned fish can quickly change a fins shape,
  making it easier for the fish to maneuver in the
  water.

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Diversity of Body Plans

• Long torpedo-shaped fish, such as barracuda are
  ambush predators.
• Fish that are flattened from side to side, like
  butterfly fish, are great at maneuvering through
  corals.
• Fish that feed on the surface of the water have
  flattened heads and mouths that point up.
• Flatfish are flat-shaped and lie on the sea floor
  waiting for their prey to swim by.
• Some slow-swimming fish use camouflage to hide
  from predators or prey.

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Staying Afloat

• Most ray-finned fish have lungs modified into a
  buoyancy organ called a Swim Bladder.
• The Swim Bladder, helps a fish float higher or
  lower in the water, by increasing and decreasing
  oxygen levels.

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Lobe-Finned Fish

• The lob-finned fish include the ancestors of all
  terrestrial vertebrates.
• Most species are extinct.
• Lobe-fins are paired pectoral and pelvic fins
  that are round in shape.
• These fins are arranged around a branching series
  of bony struts, like the limbs of a land
  vertebrate.

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Coelacanths

• Are distinctive-looking fish with thick, fleshy
  fins and a tail with three lobes.
• They breathe with gills.

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Lungfish

• Live in streams and swamps in Australia, South
  America, and Africa.
• They can breathe with either gills or lungs.

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25.4 Amphibians

• 25.4 Amphibians
• Words to Know Tetrapod, Amphibian, Tadpole

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Amphibians

• One of the oldest known fossils of a four-limbed
  vertebrate was found in 360 million-year-old
  rocks from Greenland.
• All of the vertebrates that live on land, as well
  as their descendants that have returned to
  aquatic environments, are Tetrapods.
• A Tetrapod is a vertebrate that has four limbs.
• Amphibians are animals that can live BOTH on land
  and in water.
• Amphibian literally means life on both sides.
• Depending on the species, amphibians breathe
  through their skin or with the use of gills or
  lungs.
• Amphibians have a three-chambered heart.

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Amphibian Reproduction

• Amphibians need a source of water to reproduce.
• Amphibians have several ways to stop eggs from
  drying out that include
• Laying eggs directly in water,
• Laying eggs on moist ground.
• Wrapping eggs in leaves.
• Brooding eggs in pockets on the females back.
• Some frogs start off as Tadpoles aquatic larvae
  that have gills and a broad-finned tail.

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Amphibian Metamorphosis

• To grow into terrestrial adults, tadpoles must
  undergo metamorphosis.
• Eggs hatch to release tadpoles.
• As the tadpole matures, the gills are reabsorbed
  and lungs develop.
• The circulatory system is reorganized to send
  blood to the lungs.
• The tail fin is reabsorbed.
• The body grows limbs and completely reorganizes
  its skeleton, muscles, and parts of the nervous
  system.
• Many Amphibians do NOT undergo metamorphosis and
  develop directly into their terrestrial forms.

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Three Groups of Amphibians

• Salamanders
• There are more than 300 species of salamanders.
• They have a long body, four walking limbs, and a
  tail.
• They walk with a side-t-side movement.
• They are carnivores.

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Three Groups of Amphibians

• Frogs and Toads
• There are over 3000 species of frogs.
• Toads are a family of frogs that have rougher and
  bumpier skin and are poor jumpers.
• Frogs and toads can make toxins that protect them
  from predators.

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Three Groups of Amphibians

• Caecilians
• Are legless, burrowing amphibians that live in
  the tropics.
• There are 160 species ranging in length from
  about 10 cm to 1.5 meters.
• Have banded bodies that make them look like
  earthworms.

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25.5 Vertebrates on Land

• Words to Know Amniote, Keratin, Amniotic Egg,
  Placenta

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Amniotes

• An Amniote is a vertebrate that has a thin,
  tough, membranous sac that encloses the embryo or
  fetus.
• Amniotes first appeared as small lizard-like
  creature in the late Carboniferous period.
• All Amniotes share a set of characteristics that
  prevent water loss.
• Skin cells are waterproof with Keratin a
  protein that binds to lipids inside the cell
  forming a hydrophobic layer that keep water
  inside the animal from reaching the skin.
• Kidneys and large intestines are bigger in
  amniotes than in amphibians, because they can
  reabsorb water.

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Reproduction Without Water

• The Amniotic Egg is an almost completely
  waterproof container that keeps the embryo from
  drying out as it develops.
• Once the amniotic egg evolved, vertebrates no
  longer had to go back to water for reproduction.
• Most Mammal embryos develop inside of the
  mothers reproductive tract.
• The Placenta is a membranous organ that develops
  in female mammals during pregnancy.
• It carries nutrients from mother to embryo.