The Animal Kingdom

Anatomical Positions

ANTERIORPOSTERIOR

DORSAL

VENTRAL

Directional OrientationAnterior vs. Posterior head vs. tailDorsal vs. Ventral back vs. frontMedial vs. Lateral mid-line vs. outsideDistal vs. Proximal away from core vs. toward

core

Inferior vs. Superior toward head vs. away from head

Cephalic vs. Caudal head vs. tailAboral vs. Oral opposite the mouth vs. mouth

side

Anatomical Position Review

Use the proper terms to describe the relationship between the following body parts:A) hand is ____ to the elbowB) knee is ____ to the headC) bellybutton is ____ to the spinal cordD) heart is ____ to the lungsE) head is ____ to the neck (2 terms fit here)F) wrist is ____ to the fingers

Characteristics of Animals

HeterotrophicMulticellularMovementEukaryotic

SymmetryAsymmetryRadial SymmetryBilateral Symmetry

Symmetry: Asymmetry

Irregular shapesDo not moveSponges

Symmetry: RadialCan divide into equal halves using many planes

Cnidaria (stinging animals)

Echinoderms (sea stars)

Symmetry: BilaterialCan only divide into left & right halves

Most efficient for movementFlatwormsRoundwormsMollusksSegmented WormsChordates

Bilaterally Symmetrical AnimalsPlatyhelminthsChordatesFishesHerpsBirdsRotifersMolluscsArthropodsALLOWS FOR CEPHALIZATION!

CephalizationThe process in animals by which nervous

and sensory tissues become concentrated in the "head."

Cephalization evolved several times within the animal kingdom, suggesting that it offers certain inherent advantages

the evolution of an advanced degree of cephalization in animals was associated with the evolution of a predatory lifestyle.

Benefits of Cephalization

The anterior end of the animal became most likely to first encounter food, predators, and other important features of the external environment. Flatworms (platyhelminthes) are the most primitive organisms to show cephalization

Loss of CephalizationCephalization has been lost in some

groups. Bivalves (Clams, Mussels, etc.)Echinoderms (Sea Stars)

Body Plan of OrganismsGeneral similarities in development and

form and function among members of a particular phylum

Germ LayersGerm layer is a collection of cells found in

an embryo that will give rise to all of the body’s tissues and organs.

3 Types of Germ Layers

Ectoderm – outside layer

Mesoderm – middle layer

Endoderm – inside layer

LAYER ORGAN & ORGAN SYSTEM

Ectoderm Nervous system

Skin

Sensory Organs

Mesoderm Muscles

Circulatory System

Skeletal System

Reproductive System

Endoderm Lining of gut and respiratory tracts

Liver

Pancreas

Digestive Glands

Tissue Layer Body PlansDiploblastic – ectoderm and endodermTriploblastic - ectoderm, mesoderm and

endodermAcoelomatePseudocoelomateEucoelomate

Animal Development (Embryology)

Stage 1: Fertilization

Sperm (n) meets Egg (n) to create Zygote (2n)

EmbryologyStage 2: Initial CleavageCleavage = cell divisionsThe single cell begins to divide into a solid

mass of cells (morula)

EmbryologyStage 3: BlastulationInterior of morula is pulled

awayForms blastocoel (hole

middle)Once hollow ball of cells is

created, it is now known as a blastula.

EmbryologyStage 4: GastrulationIndentation starts at pole of blastula

(blastopore)

What the blastopore becomes…

Determines if the organism is a protostome (mouth) or deuterostome (anus)

Cleavage: Radial vs. SpiralIn deuterostomes, cleavage is radialIn protostomes, cleavage is spiral

EmbryologyStage 5: Determination of Germ LayersAs cells move into blastopore; cells

differentiate and creates 2 layers of cells (endoderm & ectoderm)

The horse-shoe shapes ball is called the gastrula

EmbryologyStage 6: Coelom DevelopmentIn gastrula stage, digestive tract is formed

in the middle of the organismWhat surrounds that digestive tract is

called a body cavity (coelom) determines whether the organism is a acoelomate, pseudocoelomate or coelomate

Gastrulation VideoInvaginationCreation of Primitive Gut

Protostomes Body CavitiesAcoelomates – no body cavity

Platyhelminthes

Pseudocoelomates – fake body cavityNematodes

Deuterostomes Body CavitiesAll are Coelomates – true body cavity

MollusksAnnelidsArthropodsEchinodermsChordates