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)

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• 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. 
      

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:

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@@:

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• Body Wall.Body Cavity Diagrams:

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