Domain Eukarya – Kingdom Animalia
Origins:
 Colonial flagellated Protista, from the protozoa group
 Little to no evidence
Characteristics:
 Multicellular, eukaryotic, heterotrophic organisms
 Use ingestion:* takes in food through a mouth
 No cell walls, has intercellular junctions
 Carbohydrates stored as glycogen
 Have muscles & nervous tissue
 Life cycle
o Mainly sexual & diploid
o Eggs and sperm are the only haploid cells
o Egg & Sperm fuse, form a zygote
o Blastula:* hollow ball of cells
o Gastrula:* invaginated ball of germ layers
o Some animals have larval stage & undergo metamorphosis to form adult (can be used to distinguish the
animal groups)

Larva:* immature stage, looks different from adult

Metamorphosis:* change in body form, adult form
Distinguishing Characteristics:
 Body Plans
o Radial Symmetry:*

Mirror image; body radiate from center

Has a top & bottom but no left & right

Passive organisms, all sides equal
o Bilateral Symmetry:*

Left/right mirror image

Dorsal (top/back) & ventral (bottom/belly)

Anterior (head) & posterior (tail)

Cephalization: evolving a head
 Germ Layers: embryonic tissue layers
o Ectoderm:* outer layer

Forms the skin (outer covering) and nerves
o Mesoderm:* middle layer

Forms the muscles, bone & blood
o Endoderm:* inner layer

Forms the digestive tract and associated organs
 Organization of Tissue
o No tissues: sea sponges
o Diploblasty: 2 tissue layers

Have an endoderm and ectoderm layers

Jellyfish, sea anemones
o Triploblasty: 3 tissue layers

All higher and intermediate organisms

Two groups distinguished by development
▫ Blastopore: hole that forms in the Archenteron
▫ Archenteron: primitive gut , develops into the digestive tract

Protostomes:*
▫ Blastopore opening becomes the mouth
▫ Spiral cleavage that is determinate (cell fate is determined as they are formed)
▫ Coelom forms from the mesoderm

Deuterostomes:*
▫ Blastopore opening becomes the anus
▫ Radial cleavage that is indeterminate
▫ Coelom forms from invaginations in the gut


Types of Body cavity
o Body Cavity:* fluid filled space between the digestive tract and body wall
o Acoelomates: 3 layers, no body cavities

Flatworms
o Pseudocoelomates (pseudocoelom):*

3 layers; body cavity not surrounded by mesoderm

All are protostomes

Round worms
o Coelomates (coelom):*

3 layers; body cavity lined by mesoderm

Fluid filled cavity, allows organs to grow and move independently of the body wall

Annelids & most bilateral animals, including vertebrates
Skeletons
o Hydrostatic:* fluid, filled cavity forms a rigid structure against which muscles can contract
o Exoskeleton:* external, protects the animal, provides points for muscle attachment
o Endoskeleton:* internal, protect internal organs
Major Groupings
 Protozoa: Protista that led to kingdom (possibly)
 No true tissues: Phylum Porifera (sponges)
o Pores
o Asymmetrical
o Sessile as adults
o Diffusion for circulation & excretion
o No nerves or muscles
 True tissues: 2 Tissues. Phylum Cnidaria (jellyfish, hydra)
o 1 opening
o Radial symmetry
o 2 forms: polyp and medusa
o Gastrovascular Cavity: digestion, excretion & circulation
o Diffusion for circulation & excretion
o Basic contractile and nerve network
 True tissues: 3 tissues, bilateral symmetry
o
Acoelomates

Phylum Platyhelminthes (flatworms)
▫
▫
▫
▫

Diffusion for circ
Simple circ system
2 openings
Pseudocoelomates

Rotifera (cilia around mouth)

Nematoda (round worms)

Both have
▫
▫
▫
o
Flame cells for excrete
1 open
Nemertina (ribbonworms)
▫
▫
o
Muscle, ganglia
Ceolomic fluid as circ
Muscle
2 open
Coelomates: PROTOSTOMES, 2 openings

Mollusca (snail, clam, octopus)
 Foot, mantle, gills, CaCO3 shells
 No segments
 Open circ system (fluid bathes organs, does not stay in vessels)
Annelida (earthworms)
 No joints
 Closed circ with vessel pumps
 Metanephria for excretion
 Diffusion for gas exchange

Arthropoda - Insecta (6), arachnida (8), crustacean (10 or more legs)
 Jointed limbs, chitin exoskeleton
 Tracheal system for gas exchange
 Malphigian tubules for excrete
 Open circ with heart
Coelomates – deuterostomes (a throwback)

Echinodermata (starfish)
 Radial symmetry
 Spiny skin
 Water vascular system with tube feet for feeding, circ, diffusion
 Larva is bilateral
Coelomates – deuterostomes – Chordata - bilateral, closed cir with heart, segmented

Chordata characteristics
 Notochord
 Dorsal, hollow nerve chord
 Pharyngeal slits
 Postanal muscular tail

Urochordata and cephalochordate
 Possible paedogeneis to get chordates as Larval stage gained sexual organs

Agnatha (jawless fish), Chondrichthes (cartilage fish)
 Gills, toothlike scales
 Internal fertilization
 Eggs/live birth
 2 chamber heart

Osteichthyes (bone fish)
 Gills, flat scales
 Internal fert
 Eggs
 2 chamber heart

Amphibian
 Skin body covering
 skin, lungs, gills for gas exchange
 External fert
 Eggs/live

Reptilian
 Scale body covering
 Lungs
 Internal fert
 amniote egg Has Membranes
http://www.ucmp.berkeley.edu/vertebrates/tetrapods/amniota.html
 amnion - filled with amniotic fluid, provides stable fluid environment.
 allantois- providing for gas diffusion and removal of wastes.
 yolk sac - Food
 chorion – most exterior

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