ANIMAL KINGDOM

MAIN CHARACTERISTICS• Multicellular, eukaryotic,

heterotrophs• Specialized cells; most have

tissues• Response to stimuli by nervous

and muscular tissue• Most capable of locomotion; few

sessile• Most diploid and reproduce

sexually

ANIMALS LIVE IN DIVERSE HABITATS

• Marine

• Origin of animal life

• Provides buouyancy

• Body fluids isotonic to environment

• Plankton, nekton, sessile

• Freshwater

• Cells hypertonic to environment

• Osmoregulation

• More challenging than marine: food, oxygen, sunlight, temperature

• Terrestrial – Threat of Dessication:

• Body covering to reduce evaporation

• Respiratory organs deep in body cavity

• Reproduction

• Eggs

• Means of thermoregulation

EVOLUTION OF ANIMALS

• Common protist ancestor: choanoflagellate

• Evo-Devo

• Diversity

• Hox genes

CHARACTERISTICS USED TO FURTHER CLASSIFY ANIMALS…

BODY SYMMETRY

• Asymmetry

• Radial symmetry

• Bilateral symmetry

CEPHALIZATION

• Concentration of sensory structures in a head

• Nerve cells concentrate in head brain

• Nerve cord extends toward rear

• Found in bilaterally symmetrical organisms

• Adaptations to locomotion

EMBRYONIC DEVELOPMENT• Zygote

• Undergoes cleavage

• Develops into blastula

• Undergoes gastrulation

• Radial• Parallel or right

angles to axis• Indeterminate

• Spiral• Diagonal to axis• Determinate

2 TYPES OF CLEAVAGE PATTERNS

GERM LAYERS• Form in all animals except sponges

• 3 layers:• Ectoderm – outer layer

• Endoderm – inner layer

• Mesoderm – middle layer

DIPLOBLASTIC

TRIPLOBLASTIC

OVERVIEW OF ANIMAL TYPES• Sponges – loose arrangement of different

types of cells; do not have tissues

• Diploblastic • Cnidarians and Ctenophores• Only have 2 germ layers

• Triploblastic

• Have 3rd germ layer - mesoderm

Triploblastic organisms further grouped base on presence and type of coelom – fluid-filled cavity between digestive tract

and body wall

BODY CAVITY

BODY CAVITY CLASSIFICATION

• Acoelomates

• Solid body; no cavity

• Flatworms and ribbon worms

• Pseudocoelomates• Have a body cavity but it is not

completely lined with mesoderm

• Nematodes and rotifers

• Coelomates• Tube-within-a-tube body plan• Coelom completely lined with

mesoderm

• Comparison

2 MAIN GROUPS OF BILATERAL ANIMALS:

• During gastrulation, group of cells move in forming sac … embryonic gut

• If blastopore becomes mouth – organism is a protostome

• If blastopores becomes anus - deuterostome

PROTOSTOMES

• Flatworms, annelids, arthropods, mollusks

• Spiral, determinant cleavage

• Schizocoely

DEUTEROSTOMES

• Echinoderms and chordates

• Radial, indeterminate cleavage

• Enterocoely

PROTOSTOMES VS. DEUTEROSTOMES

Fig. 29-7, p. 627