The Deuterostomes

1
The Deuterostomes

• Chapter 31

2
Outline

• Echinoderms
• Chordates
• Invertebrates
• Vertebrates
• Fishes
• Amphibians
• Retiles
• Birds
• Mammals

3
Echinoderms

• Phylum Echinodermata
• Echinoderms have an exoskeleton of spine-bearing,
  calcium-rich plates.
• Class Crinoidea - Sea lilies.
• Class Holothuroidea - Sea cucumbers.
• Class Ophiuroidea - Brittle stars.
• Class Asteroidea - Sea stars.

4
Sea Stars

• Each arm has a groove lined by tube feet.
• Feeding structure.
• Stomach secretes enzymes.
• In each arm, coelom contains a pair of digestive
  glands and gonads.
• Locomotion depends on water vascular system.
• Simple circulatory system.

5
Echinoderms
6
Chordates

• Phylum Chordata
• Four Main Characteristics
• Notochord
• Nerve Cord
• Pharyngeal Pouches
• Tail

7
Invertebrate Chordates

• Notochord persists and is never replaced by a
  vertebral column.
• Lancets (Subphylum Cephalochordata)
• Sea Squirts (Subphylum Urochordata)

8
Invertebrate Chordates
9
Vertebrates

• Subphylum Vertebrata
• Vertebrate skeleton is living tissue that grows
  with the animal.
• Main axis of internal jointed skeleton consists
  of vertebral columns and a skull that encloses
  the brain.
• Cephalization is accompanied by sense organs.
• Evolution of jaws and predation.
• Amnion allows reproduction on land.

10
Vertebrate Features

• Living endoskeleton with vertebral column.
• Closed circulatory system.
• Paired appendages.
• Efficient respiration and excretion.
• High degree of cephalization.
• Adapted to active lifestyles.

11
Fishes

• Fishes are aquatic, gill-breathing vertebrates
  that usually have fins and scale-covered skin.
• Jawless fishes (Superclass Agnatha)
• Ostracoderms - earliest vertebrate fossils.
• Lampreys and hagfishes are modern-day jawless
  fishes that lack a bony skeleton.

12
Jawless Fishes
13
Fishes With Jaws

• Gnathostomates have jaws.
• Believed to have evolved from first pair of gill
  arches of agnathans.
• Placoderms, extinct jawed fishes of Devonian
  period, are believed to be ancestral to early
  sharks and bony fish.

14
Cartilaginous Fishes

• Class Chondrichthyes have a skeleton of cartilage
  instead of bone.
• Cartilaginous Fishes
• Sharks, rays, skates
• Lack gill cover of bony fish.
• Utilize lateral line system.
• Filter feeders and predators.
• Pectoral fins can be enlarged into large,
  winglike fins.

15
Cartilaginous Fishes
16
Bony Fishes

• Class Osteichthyes have a skeleton of bone.
• Most are ray-finned fishes.
• Lobe-finned fishes are small subgroup with fleshy
  fins supported by central bones.
• Bony fish have a gas-filled sac (swim bladder)
  whose pressure can be altered to change buoyancy.

17
Ray-Finned Fishes
18
Amphibians

• Tetrapods (Have four limbs)
• Hypotheses of evolution.
• Lobe-finned fishes had an evolutionary advantage
  due to movement capability.
• Supply of food on land and the absence of
  predators promoted further adaptations.

19
Lobe-Finned Fish Versus Amphibians
20
Diversity of Amphibians

• Amphibians today occur in three groups
• Salamanders and newts
• Salamanders practice internal fertilization.
• Frogs and toads
• Tailless
• Caecilians
• Legless, sightless, worm-shaped
• Most return to water for reproduction.

21
Amphibians
22
Amphibian Features

• Usually tetrapods.
• Lungs usually present in adults.
• Metamorphosis
• Smooth and moist skin.
• Three-chambered heart.
• Ectothermic

23
Vertebrate Circulatory Systems
24
Reptiles

• Class Reptilia is believed to have evolved from
  amphibian ancestors by the Permian period.

25
Phylogenetic Tree
26
Reptiles

• Practice internal fertilization and lay eggs
  protected by a leathery shell (amniotic egg).

27
Anatomy and Physiology of Reptiles

• Reptiles have a thick, scaly skin that is
  keratinized and impermeable to water.
• Usually tetrapods.
• Lungs with expandable rib cage.
• Shelled amniotic egg.
• Dry, scaly skin.
• Ectothermic

28
(No Transcript)
29
Birds

• Characteristics of Class Aves
• Feathers
• Hard-shelled amniotic egg.
• Four-chambered heart.
• Often winged
• Air sacs
• Endothermic

30
(No Transcript)
31
Bird Beaks
32
Mammals

• Class Mammalia evolved during the Mesozoic era
  from therapsids.
• Mammalian skull accommodates a larger brain
  relative to body size.
• Chief characteristics and hair and milk-producing
  mammary glands.
• Infant Dependency
• Internal Development
• Differentiated Teeth

33
Mammals

• Monotremes - Hard-shelled amniotic eggs.
• Marsupials - Females contain pouch.
• Placentals - Females have organ for exchange of
  maternal and placental blood.

34
Major Orders of Mammals

• Perissodactyla
• Horses
• Artiodactyla
• Deer
• Carnivora
• Cats
• Primates
• Monkeys
• Cetacea
• Whales

• Chiroptera
• Bats
• Rodentia
• Mice
• Proboscidea
• Elephants
• Lagomorpha
• Rabbits

35
Review

• Echinoderms
• Chordates
• Invertebrates
• Vertebrates
• Fishes
• Amphibians
• Retiles
• Birds
• Mammals

36
(No Transcript)