knowt logo

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

  1. 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

  1. Segmentation: repeating parts

    1. Segments can become specialized

      1. Examples: legs, flippers, wings, etc.

    2. Bilaterally symmetrical animals

    3. Annelids (Earthworm)

  2. 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:

Phylum

Example(s)

Germ Layers

Symmetry

Cephalization

Early Development (Blastopore formation)

Porifera

Sponges

absent

asymmetrical

absent

none

Cnidarian

Sea Anemones

two

radial

absent

none

Platyhelminth-es

Flatworms

two

bilateral

present

protostome

Nematoda

Roundworms

three

bilateral

present

protostome

Annelida

Earthworms

three

bilateral

present

protostome

Mollusca

Snails

three

bilateral

present

protostome

Echinodermata

Starfish

three

radial

absent

deuterostome

Arthropoda (Largest Phylum)

Crabs

three

bilateral

present

protostome

(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:

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

  1. 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

  1. Segmentation: repeating parts

    1. Segments can become specialized

      1. Examples: legs, flippers, wings, etc.

    2. Bilaterally symmetrical animals

    3. Annelids (Earthworm)

  2. 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:

Phylum

Example(s)

Germ Layers

Symmetry

Cephalization

Early Development (Blastopore formation)

Porifera

Sponges

absent

asymmetrical

absent

none

Cnidarian

Sea Anemones

two

radial

absent

none

Platyhelminth-es

Flatworms

two

bilateral

present

protostome

Nematoda

Roundworms

three

bilateral

present

protostome

Annelida

Earthworms

three

bilateral

present

protostome

Mollusca

Snails

three

bilateral

present

protostome

Echinodermata

Starfish

three

radial

absent

deuterostome

Arthropoda (Largest Phylum)

Crabs

three

bilateral

present

protostome

(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:

robot