Chapter 11. Diversification of the Eukaryotes Animals

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Chapter 11. Diversification of the Eukaryotes Animals Powered By Docstoc
					Animal Diversity
Learning Goals

    Describe what it means to be an animal
    Identify the key distinctions that divide the species
    Discuss evolutionary success
    Describe vertebrates and their evolution
    Define and describe the terrestrial vertebrates,
     including amphibians, birds, and mammals
    Define and describe the invertebrates, including
     echinoderms, arthropods, molluscs, annelids,
     flatworms, cnidarians, and sponges
What is an animal?
Some Key Characteristics
 Animals: How do we tell one
   group from the other?
 Cellular nature (single celled or multicellular)
 Symmetry (none, radial, bilateral)
 Digestive system (complete or incomplete)
 Segmentation (present of absent)
 Skeleton (exoskeleton vs. endoskeleton)
 Regulation (ecothermic or endothermic)
 Fertilization (internal or external)
 Fate of the blastopore (mouth or anus)
Embryological Development

 Fertilized Egg (Zygote)
 Morula
 Blastula
 Gastrula
 Blastopore

 It is not birth, death or marriage which is the
  most important event in your life…but

 First Tissues
   Ectoderm
   Mesoderm
   Endoderm
    Evolutionary Success
   From an evolutionary perspective, all species
    existing today are successful

   Among the 36 animal phyla, 9 phyla account for
    more than 96 percent of all described animal

   We will study these 9 animal groups
features of
The Most Diverse Subphylum of
Chordates = The Vertebrates
Vertebrate Evolution

   In the transition of vertebrates from life in water
    to life on land:

    • fins were modified into limbs

    • vertebrae were modified to transmit weight to the

    • the site of gas exchange was transferred from gills to
Invertebrates are the largest and
most diverse group of animals
Invertebrate Evolution

   Invertebrates, defined as animals without a
    backbone, are the largest and most diverse
    group of animals, comprising 96% of all the
    living species of animals

   The invertebrates are not a monophyletic group,
    however, and include protostomes and
Evolutionary Specialization

   Include star fish, sea urchins and sand dollars

   Radial symmetry in adults

   An evolutionary specialization associated with
    locomotion (tube feet) and feeding (stomach
    through anus)
Echinoderms and Chordates

   Bilateral symmetry in larvae

   The larvae have anatomical characteristics in
    common with the larvae of primitive chordates

   Echinoderms and chordates are each other’s
    closest relatives

   The arthropods are protostome invertebrates
    and include the insects, spiders and crustaceans

   The life cycle of most insects includes a larval
    stage (eating), a pupa stage (transformation)
    and an adult stage (reproduction)
Arthropods: Natures Success
   This separation of life stages has contributed to
    the enormous ecological diversity and success of

   It has also produced remarkable specializations
    among the nearly 1 million species of insects
    that have been named
Other arthropods include
arachnids, crustaceans,
millipedes, and centipedes

 Include snails, octopus, squid and clams
 All molluscs have:
   Shell
   Mantle
   Radula
The Three Major Groups of
1) Gastropods = “belly foot” include snails, slugs
   make up ¾ of all molluscs, herbivores,
   omnivores, some predators

2) Bivalves = clams, mussels, possess two shells,
   filter feeders

3) Cephalopods = “head foot” include octopus,
   squid, predators
   Worms fall into several different phyla and are
    not a monophyletic group

   All are bilaterally symmetrical protostomes with
    defined tissue

   Worms
     Segmented worms = annelids, earthworms
      (important decomposers)
     Flatworms = planarians
     Roundworms = nematodes
Segmented worms
come in all
shapes and

   Jellyfish, Sea Anemones, Coral

   Two types of cnidarian bodies:
    • a sessile polyp
    • a free-floating medusa

   Carnivores that use stinging cells

   Sponges are among the simplest of the lineages
    of animals

   A sponge consists of a hollow tube with pores in
    its wall, it has no tissues or organs

   Filter feeders

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