Zoology – the study of animals.

There are 1.5 million+ animals (estimates as high as 3 million undescribed).

Classified into 35 current Phylums

Phylum Arthropoda = 1.2 million+ named species.

Mammals represent only about 5, 000 named species!

Zoology Disciplines

Comparative Anatomy – the study of structures and functions of various animal groups.

Taxonomy – the science of finding, describing, and classifying animals.

Entomology – the study of insects. Ichthyology – the study of fish Herpetology – the study of reptiles and amphibians. Ethology – the study of animal behavior. Malacology – the study of molluscs. Myrmecology – the study of ants. Helminthology – the study of worms

What is an Animal?

Petunia is a plant and

Wolf spider is an animal.

What is an Animal?

Coral

sessile (“rooted”?)

stem, branches,

greenish.

Resembles plant;

but this IS an animal! Why?

What IS an Animal?

Definition of "Animal"

Multicellular (so are plants, fungi)

Eukaryotic (so are plants, fungi)

Diploid (usually) (so are plants, fungi)

Meiosis produces gametes called sperm and egg

Sperm, egg are the only haploid cells

Heterotrophic by ingestion

Cells lack cell walls.

What IS an Animal?

Basic structure (not definition) = Tube-in-tubeBody wall = outer tube

gut (GI tract) = inside tubemouth

anus

Embryological Development in Animals

Every animal begins as ZYGOTE

How do animals develop tube-in-tube body form?

Important in understanding relationships, classification of Phyla.

Three fundamental processes:

1. Morphogenesis

(morph- = shape, + genesis = origin)

Origin of shape, form

2. Differentiation

Process of cells becoming different, and specializing for different functions

3. Growth

Increase in size, requires input of matter, food

Embryology Sequence of Events:

1. Fertilization

2. Cleavage

3.Gastrulation

4.Organogenesis

1. Fertilization

Gametes join in fertilization

gametes are produced (gametogenesis) through meiosis

What process produces every other cell in the human body?

MITOSIS

Let the Division Begin!

2. Cleavage

Cleavage is a series of rapid mitotic divisions (without cell growth)

The two-celled zygote divides repeatedly until a ball of 32 cells is formed

This is the morula - 32 cells

Continued divisions make the hollow blastula

These few cells are pluripotent (have the potential to become ANY of the 220 types of cells in the human body).

These are embryonic stem cells

3. Gastrulation Gastrulation = formation of a gut;

Major MORPHOGENIC event !!! At the end of the cleavage stage, cells making up the

blastula move about and surface proteins help cells recognize each other

Location of cells after GASTRULATION determines further development

The gastrula is formed, which can consists of 3 “germ layers”

1. Endoderm “inside skin” 2. Mesoderm “middle skin” 3. Ectoderm “outside skin” Will yield Archenteron in primitive animals

“ancient gut” = first formation of "inside tube."

Development in Classification

Tissues -collections of specialized cells working together and isolated from other tissues by membranous layers. (germ layers)

•Diploblastic Animals–Have two germ layers, ectoderm and

endoderm. (Jellyfish)•Triploblastic Animals–Have three germ layers, ecto-,

meso-, and endoderm. (Vertebrates)

Gastrulation

Zygote

Cleavage

Eight-cell stage

Cleavage

Blastula Cross section of blastula

Blastocoel

Blastocoel

Gastrula Gastrulation

Endoderm

Ectoderm

Blastopore

Early embryonic development in animals

In most animals, cleavage results in theformation of a multicellular stage called a blastula.The blastula of many animals is a hollow ball of cells.

3

The endoderm ofthe archenteron de-

velops into the tissuelining the animal’s

digestive tract.

6

The blind pouchformed by gastru-

lation, calledthe archenteron,

opens to the outsidevia the blastopore.

5

Most animals also undergo gastrulation, a rearrangement of the embryo in which one end of the embryo folds inward, expands, and eventually fills the blastocoel, producing layers of embryonic tissues: the ectoderm (outer layer) and the endoderm (inner layer).

4

Only one cleavagestage–the eight-cellembryo–is shown here.

2 The zygote of an animal undergoes a succession of mitotic cell divisions called cleavage.

1

Body Cavity Development

Body Cavity (Coelom) – is a fluid-filled space separating digestive tract from outer body wall.

Cushions internal organs, allows internal organs to move independently of the outer body wall, hydroskeleton in some animals (earthworm).

Animals with no coelom - acoelomates

Animals with a true coelom – coelomates – coelom forms from mesoderm to become mesenteries and suspend internal organs.

Animals form a cavity from the blastocoel - pseudocoelomates

Organisms without body cavities

Are considered acoelomates

Body covering(from ectoderm)

Tissue-filled region(from mesoderm)

Digestive tract(from endoderm)

Acoelomate. Acoelomates such as flatworms lack a body cavity between the digestive tract and outer body wall.

A pseudocoelom

a body cavity derived from the blastocoel, rather than from mesoderm

Pseudocoelom

Muscle layer(from mesoderm)

Body covering(from ectoderm)

Digestive tract(from ectoderm)

Pseudocoelomates such as nematodes have a body cavity only partially lined by tissue derived from mesoderm.

A true body cavity is called a coelom and is derived from mesoderm

Coelom

Body covering(from ectoderm)

Digestive tract(from endoderm)

Tissue layerlining coelomand suspendinginternal organs(from mesoderm)

Coelomate. Coelomates such as annelids have a true coelom, a body cavity completely lined by tissue derived from mesoderm.

Coelomates will further branch into either a Protostome or Deuterostome

Based on certain features seen in early development

3 Characteristics Determine the Group:

Cleavage Pattern (Cell Division)

Coelom Formation

Fate of the Blastopore

Cleavage Pattern (Cell Division)

In protostome development

Cleavage is spiral (mitotic spindles at diagonals to embryo axis) and determinate (cells fixed on a developmental pathway)

In deuterostome development

Cleavage is radial (spindles parallel and perpendicular) and indeterminate (cells can adjust)

Protostome development(examples: molluscs, annelids,

arthropods)

Deuterostome development(examples: echinoderms,

chordates)

Eight-cell stage Eight-cell stage

Spiral and determinate Radial and indeterminate

(a) Cleavage. In general, protostomedevelopment begins with spiral, determinate cleavage.Deuterostome development is characterized by radial, indeterminate cleavage.

Coelom Formation

In protostome development, the solid mass of mesoderm cells split to form the coelom

In deuterostome development, mesoderm buds from endoderm

Fate of the Blastopore

In protostome development the blastopore becomes the mouth

In deuterostome development the blastopore becomes the anus

Anus

Anus

Mouth

Mouth

Mouth developsfrom blastopore

Anus developsfrom blastopore

Digestive tube

4. Organogenesis

Organogenesis Purpose: Formation of organs from three germ layers

Differentiation & continued Morphogenesis

1. Ectoderm will form the following: Epidermis

Lining of mouth & rectum

Cornea of eye

Lens of eye

Nervous system

Thin linings of gut & branches

lining of excretory ducts, bladder

Lining of lungs, trachea

Lining of reproductive ducts, uterus, vas deferens

liver

pancreas

Organogenesis

2. Mesoderm will form the following:

Skeleton,

Muscles (skeletal, smooth, cardiac)

Dermis of skin

Heart, blood, blood vessels

Kidneys,

Ovaries/testes, etc.

Organogenesis

3. Ectoderm forms the following:EpidermisHow Nervous system

gets insidea. Dorsal surface of embryo forms Neural plate

b. Plate sinks inward forming Neural groove

c. Edges of groove fuse to separate Neural tube from epidermis

Extraembryonic Membranes

These membranes develop from the germ layers, but are NOT part of the embryo (they are lost at birth)

They lie outside of the embryo & provide protection and nourishment

Four exist in terrestrial vertebrates:Chorion, amnion, allantois (stores

nitrogenous waste in reptiles), & yolk sac (not found in humans, but yolk aids in formation of RBC

Human Development

The gestation period lasts 266 days from fertilization to birth

Organogenesis (development of the organs and organ systems) begins with the nervous system

Think on this:

Do all animals have the same gestation period?

Patterns of Organization

4 Ways of Animal Organization:

• Symmetry (Asymmetry, Radial, Bilateral)

• Tissue Organization (Diploblastic, Triploblastic)

• Body Cavity Development (Acoelomate, Pseudocoelomate, Coelomate)

• Embryological Development (Protostome and Deuterostome)

Symmetry

• Asymmetry – arrangement of body parts without a central axis or point (sponges).– No complex sensory or locomotion functions.

• Radial Symmetry – arrangement of body parts such that a single plane passing through the oral-aboral axis divides the animal into mirror images (sea anemones, starfish).– No blind side.

• Bilateral Symmetry - arrangement of body parts such that a single plane passing through the longitudinal axis divides the animal into right and left mirror images (vertebrates).– Cephalization – form distinct head to analyze the environment as they

move through it.

Some animals have radial symmetry like in a flower pot

Radial symmetry. The parts of a radial animal, such as a sea anemone (phylum Cnidaria), radiate from the center. Any imaginary slice through the central axis divides the animal into mirror images.

Some animals exhibit bilateral symmetry or two-sided symmetry

Bilateral symmetry. A bilateral animal, such as a lobster (phylum Arthropoda), has a left side and a right side. Only one imaginary cut divides the animal into mirror-image halves.

What Kind of Symmetry Do I Have?

What Kind of Symmetry Do I Have?

What Kind of Symmetry Do We Have?

Anatomical Planes and Directions

7-9

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

Fig. 7.9

Sagittal plane

Bilateral Symmetry

Directional Terms

1. Anterior and Posterior

a. Anterior refers to being towards the front

b. Posterior refers to being towards the back

2. Dorsal and Ventral

a. Dorsal refers to the upper back region

b. Ventral refers to the bottom region, relating to the underside

Directional Terms

3. Superior and Inferior

a. Superior refers to being above

b. Inferior refers to being below

Directional Terms

4. Proximal and Distal

a. Proximal refers to being closer to a point of attachment or the trunk

b. Distal refers to being farther away from a point of attachment or the trunk

Directional Terms

5. Medial and Lateral

a. Medial refers to being closer to a vertical midline

b. Lateral refers to being closer to the sides with relation to the midline

Directional Terms

6. Superficial and Deep

a. Superficial refers to being closer to the surface

b. Deep refers to being more internal

7. Plantar

Refers to the sole of the foot

Body Planes (Sections)

The body can be sectioned in three different planes. Each one gives a different perspective.

Body Planes (Sections)

1. Sagittal Section – lengthwise (vertical) cut that divides the body into right & left halves

2. Transverse Section – horizontal cut that divides the body into inferior and superior portions

3. Coronal Section – vertical cut that divides the body into anterior & posterior portions

Hot Dog DissectionObjectives: The student will become familiar with directional terminology. The student will become familiar with body section cuts.

Procedure: Identify the superior and inferior position on your specimen.

Label these regions on your paper plate. Identify the anterior and posterior position on your specimen. Using a permanent marker, draw a sagittal body plane on the

anterior portion of your specimen. Specimen must be dry for this!

Discuss with your partner how medial & lateral relate to this sagittal plane.

Make a medial superficial incision on the posterior side from the superior to the inferior position.

Now make a superficial transverse incision on the anterior side proximal to the arms.

On the inferior, anterior tip, remove a 1-inch section. Use this section to cut a coronal section.

Label the plantar region. Using the examples in your notes, relate the body terminology

to the relative position terminology.