The Animal Kingdom

Anatomical Positions ANTERIOR POSTERIOR DORSAL VENTRAL

Directional Orientation Anterior vs. Posterior  head vs. tail Dorsal vs. Ventral  back vs. front Medial vs. Lateral  mid-line vs. outside Distal vs. Proximal  away from core vs. toward core Inferior vs. Superior  toward head vs. away from head Cephalic vs. Caudal  head vs. tail Aboral 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 elbow B) knee is ____ to the head C) bellybutton is ____ to the spinal cord D) heart is ____ to the lungs E) head is ____ to the neck (2 terms fit here) F) wrist is ____ to the fingers

Characteristics of Animals Heterotrophic Multicellular Movement Eukaryotic

Symmetry Asymmetry Radial Symmetry Bilateral Symmetry

Symmetry: Asymmetry Irregular shapes Do not move Sponges

Symmetry: Radial Can divide into equal halves using many planes Cnidaria (stinging animals) Echinoderms (sea stars)

Symmetry: Bilaterial Can only divide into left & right halves Most efficient for movement Flatworms Roundworms Mollusks Segmented Worms Chordates

Bilaterally Symmetrical Animals Platyhelminths Chordates Fishes Herps Birds Rotifers Molluscs Arthropods ALLOWS FOR CEPHALIZATION!

Cephalization The 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 Cephalization Cephalization has been lost in some groups. Bivalves (Clams, Mussels, etc.) Echinoderms (Sea Stars)

Body Plan of Organisms General similarities in development and form and function among members of a particular phylum

Germ Layers Germ 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

LAYERORGAN & ORGAN SYSTEM EctodermNervous system Skin Sensory Organs MesodermMuscles Circulatory System Skeletal System Reproductive System EndodermLining of gut and respiratory tracts Liver Pancreas Digestive Glands

Tissue Layer Body Plans Diploblastic – ectoderm and endoderm Triploblastic- ectoderm, mesoderm and endoderm Acoelomate Pseudocoelomate Eucoelomate

Animal Development (Embryology) Stage 1: Fertilization Sperm (n) meets Egg (n) to create Zygote (2n)

Embryology Stage 2: Initial Cleavage Cleavage = cell divisions The single cell begins to divide into a solid mass of cells (morula)

Embryology Stage 3: Blastulation Interior of morula is pulled away Forms blastocoel (hole middle) Once hollow ball of cells is created, it is now known as a blastula.

Embryology Stage 4: Gastrulation Indentation starts at pole of blastula (blastopore)

What the blastopore becomes… Determines if the organism is a protostome (mouth) or deuterostome (anus)

Cleavage: Radial vs. Spiral In deuterostomes, cleavage is radial In protostomes, cleavage is spiral

Embryology Stage 5: Determination of Germ Layers As cells move into blastopore; cells differentiate and creates 2 layers of cells (endoderm & ectoderm) The horse-shoe shapes ball is called the gastrula

Embryology Stage 6: Coelom Development In gastrula stage, digestive tract is formed in the middle of the organism What surrounds that digestive tract is called a body cavity (coelom) determines whether the organism is a acoelomate, pseudocoelomate or coelomate

Gastrulation Video Invagination Creation of Primitive Gut

Protostomes Body Cavities Acoelomates – no body cavity Platyhelminthes Pseudocoelomates – fake body cavity Nematodes

Deuterostomes Body Cavities All are Coelomates – true body cavity Mollusks Annelids Arthropods Echinoderms Chordates