Introduction to Animals

Major Characteristics That All Animals Share:

  • Kingdom Animalia
    • So they’ll differentiate on the phylum level
  • Multicellular
  • Heterotrophic
  • Eukaryotic
  • Lack cell walls

Different Description Types of Animals

  • Level of Organization
  • Body Cavity
  • Number of Tissue Layers
  • Segmentation
  • Blastopore: (Protostome or Deuterostome)
  • Cephalization
  1. Levels of Organization:

    1. Cells

    2. Tissue

      1. Diploblastic or Triploblastic
    3. Organs

    4. Organ systems

    5. Organisms

      1. Simplest animals: just specialized cells to organs to organism

      2. Complex animals: Cell to tissue to organ to system to organism

        1. Just because an animal is more complex than another does not make it a “better” animal. There is no such thing.
  2. Differentiation of Germ Layers: (absent, two, or three)

  • During embryological development, cells begin to differentiate (activate) into three layers (called germ layers)
    • Endoderm: Forms digestive and respiratory systems
    • Mesoderm: Forms muscular, reproductive, circulatory, and excretory systems (muscles)
    • Ectoderm: Forms nervous and integumentary systems (skin/outer covering)
  • Classifications:
    • Diploblastic: having 2 germ layers
    • Triploblastic: having 3 germ layers
  1. Formation of Body Cavity:

==Body Cavity:== fluid filled space between digestive tract and body wall

  1. Coelem: complex animals have true body cavity completely lined with mesoderm

    1. <<In coelemates the endoderm forms a circular digestive tube that is surrounded by a thin layer of muscle<<
  2. Psuedocoelem: some invertebrates, only partially lined with mesoderm

    1. <<In psuedocoelemates the endoderm forms a crescent shape digestive tube<<
  3. Acoelomate: lack coelem between body wall and digestive tract (just a tube of flesh w/ body wall)

    1. <<In acoelomates the endoderm forms a triangular digestive cavity<<

      1. ==All three germ layers are present in each one (just formed differently)==
    2. ==Advantage to having a body cavity: Have room for specialized organs==

  4. Blastopore Classification

Blastopore: Opening in blastula

  1. Zygote: fertilized egg that gives rise to blastula
  • Blastula: hollow ball of cells that eventually folds into itself (creating the beginning of a digestive tract)

  • Different Groups:

    • ==Protostome: blastopore gives rise to the mouth==
    • invertebrates
    • ==Deuterostome: blastopore gives rise to anus==
    • Chordates and echinoderms (starfish)
  1. Body Symmetry Classification:

Radial: body parts extend outward from the center

  1. Cnidarians and Echinodermata

  2. Bilateral: body parts have identical left and right sides

    1. Platyhelminthes, Nematoda, Annelida, Mollsuca, Arthropoda, Invertebrate Chordates, and Vertebrates
  3. Asymmetrical: no symmetry

    1. Porifera
  4. Segmentation: repeating parts

    1. Segments can become specialized

      1. Examples: legs, flippers, wings, etc.
    2. Bilaterally symmetrical animals

    3. Annelids (Earthworm)

  5. Cephalization Classification:

    1. concentration of sense organs and nerve cells

Invertebrates:

Invertebrate Characteristics/Overview:

  • Lack a backbone or vertebral column
  • Includes 33 phyla (largest group)

Different Phyla Include:

  • Phylum Porifera

  • Phylum Cnidarian

  • Phylum Arthropoda

  • Phylum Platyhelminthes

  • Phylum Nematoda

  • Phylum Echinodermata

  • Phylum Annelida

  • Phylum Mollusca

    Invertebrate Phylums and Their Individual Classifications Table:

PhylumExample(s)Germ LayersSymmetryCephalizationEarly Development (Blastopore formation)
PoriferaSpongesabsentasymmetricalabsentnone
CnidarianSea Anemonestworadialabsentnone
Platyhelminth-esFlatwormstwobilateralpresentprotostome
NematodaRoundwormsthreebilateralpresentprotostome
AnnelidaEarthwormsthreebilateralpresentprotostome
MolluscaSnailsthreebilateralpresentprotostome
EchinodermataStarfishthreeradialabsentdeuterostome
Arthropoda (Largest Phylum)Crabsthreebilateralpresentprotostome
}}(Not Phylum) Invertebrate Chordates}}}}Tunicates}}}}three}}}}bilateral}}}}absent}}}}deuterostome}}
}}Vertebrates}}(Not Invertebrates)}}Birds, Humans}}}}three}}}}bilateral}}}}present}}}}deuterostome}}

Quick Sight List:

  • Phylum Porifera: absent germ layers, asymmetrical, no cephalization, and no blastula rise
  • Phylum Cnidarians: two germ layers, radial symmetry, no cephalization, and no blatstula rise
  • Phylum Platyhelminthes: three germ layer, bilateral symmetry, cephalization, a protostome
  • Phylum Nematoda: three germ layers, bilateral symmetry, cephalization, a protostome
  • Phylum Annelida: three germ layers, bilateral symmetry, cephalization, a protostome
  • Phylum Mollusca: three germ layers, bilateral symmetry, cephalization, a protostome
  • Phylum Arthropoda: three germ layers, bilateral symmetry, cephalization, a protostome
  • Phylum Echinodermata: three germ layers, radial symmetry, no cephalization, a deuterostome
  • Invertebrate Chordates: three germ layers, bilateral symmetry, no cephalization, a deuterostome
  • Vertebrates: three germ layers, bilateral symmetry, cephalization, a protostome

Relationship Between Echinodermata and Chordates:

  • Invertebrates of the Phylum Echinodermata are the closest cousins to the chordates

Characteristics of All Chordates (that they will exhibit at some point in life):

  • ==Dorsal hollow nerve cord==: the major cord of nerve fibers running the length of the animal’s body that can develop into the %%spinal chord%% in vertebrates
  • ==Notochord==: supporting rod below the nerve cord that gives rise to the %%(intervebral disc)%% in vertebrates
  • ==Tail== that extends below the anus that gives rise to the %%(tailbone)%% in vertebrates
  • ==Pharyngeal pouches/sacs==: lateral sacs that branch from the pharynx of chordate embryos and may open outside as %%gill slits%% in adult fishes (vertebrates) and invertebrate chordates

@@Difference between Invertebrates and Vertebrates?@@

  • Vertebrates are just chordates that have a @@backbone@@ while invertebrates lack a backbone or vertical column

Diagrams:

  • Invertebrate Chordates: @@Cephalochordata@@:

  • Body Wall.Body Cavity Diagrams:

    • \