1. 1
Characteristics of Animals
- evolved from protists
- eukaryotic
- lack cell walls
- multicellular
- heterotrophic
- ingest food most
- digestive cavity
Animal Flow Chart
Animal

2. 2
Early Embryonic Development in Animals
(Cell Differentiation)
_____________________________ _____________________________ _____________________________
1. 1. 1.
Germ layers:
a. _____________________
-
-
b. _____________________
-
-
-
c. _____________________
-

3. 3
Body Plans
Symmetry:
One way in which scientists categorize the diversity of animals is according to the symmetry of their bodies (or its absence).
1. ________________________ 2. ________________________ 3. ________________________
No body symmetry Any number of lines can be drawn One line can be drawn that divides
through the center, each dividing the body into equal halves
the body into equal halves. (have a left & right half)
Ex. Ex. Ex.
Lifestyle: Lifestyle: Lifestyle:
Sessile –don’t move Sessile Move actively from place to place
Planktonic – drift or weakly swimming

4. 4
Tissues:
Animal plans vary according to the organization of the animal’s tissues layers (germ layers).
- Sponges lack true tissues. In all other animals, the embryo becomes layered through the process of gastrulation. As development progresses, these
germ layers form more specialized tissues and organs that make up the body.
o Diploblastic - animals that have only 2 germ layers (Endoderm, ectoderm).
 Ex. Cnidarians
o Triploblastic - animals that have only 3 germ layers (Endoderm, mesoderm, ectoderm)
 Ex. All bilaterally symmetrical animals & Echinoderms
Body Plans of Triploblastic Animals
1. ________________________ 2. ________________________ 3. ________________________
Acoelomate Pseudocoelomate Coelomate

5. 5
1. 1. 1.
2. 2. 2.
3. 3. 3.
4.
Ex. Ex. Ex.
Protostome & Deuterostome Development:
Based on certain features of early development, many animals can be categorized as having one of two developmental modes:
- Coelomates can be divided into 2 evolutionary groups based on several fundamental differences in their development.
- Protostomes include: Segmented worms, mollusks, arthropods
- Deuterostomes include: Echinoderms, chordates
Comparison of Protostome & Deuterostome Development

6. 6
Spiral cleavage vs. Radial cleavage
Schizocoelous: Endoderm cells form solid masses of Enterocoelous: Certain cells of the endoderm differentiate
Mesoderm which then split to form coelom into mesoderm and form outpockets of the archenteron.
Coelom Formation

7. 7
Protostome vs. Deuterostome
Characteristic Protostome Deuterostome
Cleavage
Developmental fate
Blastopore fate
Coelom formation
Developmental fate

8. 8
Sponges
- simplest of all animals
- lack true tissues and organs (parazoa)
- symmetry → asymmetrical
- sessile
- most are hermaphroditic
- no gastrula stage
Obtaining food:
- Filter feeding - filters small particles (bacteria) of food from the water.
Reproduction:
Asexual:
- Budding - forms a growth or bud that eventually falls off
- Fragmentation - a piece breaks off
- Gemmules - seed-like particles that fall from the sponge & grow into a new sponge
Sexual:
- Internal fertilization - Amoebocytes produce eggs and sperm. Sperm then swim to a different sponge
and fertilize eggs.
o Hermaphrodites
Structure:

9. 9
Cnidarians
- Symmetry → radially symmetrical
- Diploblastic - produce only 2 germ layers (endoderm & ectoderm)
- 2-way digestive tract (incomplete)
- Hydrostatic skeleton – a skeletal system composed of fluid held under pressure in a closed body
compartment.
- Cnidocytes – stinging cells that contain nematocysts – stinging capsule
- 2 basic forms: most undergo a change in body form during their life cycle
o Medusa - the free swimming form
o Polyp- the sessile form
Obtaining food:
Tentacles & cnidocytes are used to capture food. Food is then put into a gastrovascular cavity where it
is digested. Undigested materials are ejected back out through the mouth.
Nervous system:
Nerve net - a loose association of nerves with no control center.
Reproduction:
Asexual
a. Budding - an outgrowth that eventually falls off and develops into an adult
Sexual
a. External fertilization - sperm and egg form a zygote in water.
-
Structure:

10. 10
Platyhelminthes (flatworms)
- acoelomates with thin, solid bodies
- 2-way digestive tract
- Triploblastic - produce 3 germ layers (endoderm, mesoderm, ectoderm)
- hydrostatic skeleton (all bilaterally symmetrical animals are triploblastic)
- Cephalization – has a head or control center
- symmetry → bilaterally symmetrical
- grouped into 3 classes:
o free-living planarians
o parasitic flukes
o parasitic tapeworms
Planarians:
Obtaining food:
- Extends pharynx
- Releases digestive enzymes
- Food particle s are sucked in through pharynx
- Food is endocytosed and digested by individual cells
- Wastes are eliminated through pharynx
Reproduction:
Asexual
Fission (regeneration) - worm splits in 2 and then regenerates its missing halves.
Sexual reproduction
Structure:

11. 11
Tapeworms:
- parasitic
- can grow to 20 ft in length
Obtaining food:
- Have no mouth, gastrovascular cavity, or digestive organs.
- Absorb nutrients through their
Reproduction:
- Have a complex reproductive life cycle

12. 12
Nematodes (roundworms)
- pseudocoelomates
- 1-way digestive tract (complete)
o Anterior region of the tract churns and mixes food with enzymes for digestion. The posterior
region absorbs nutrients and disposes of wastes. This step-by-step processing of food allows
each part of the digestive tube to be highly specialized for its particular function.
- No circulatory system (simple diffusion)
- hydrostatic skeleton
- cylindrical worms with lengthwise muscles
o moves by a thrashing motion
- cuticle covers the body; as the worm grows, it periodically sheds its old cuticle (molting).
- most numerous of all animals on Earth
- many roundworms are parasitic.

13. 13
Annelids (segmented worms)
- symmetry → bilaterally symmetrical
- coelomate
- hydrostatic skeleton
- tube within a tube body plan
- bodies are cylindrical and segmented
o allows shortening & lengthening of body
o segmentation allows for specialization of a particular function
- have setae (tiny bristles) on each segment
Circulation:
- closed circulatory system - blood remains within vessels
- 5 aortic arches (hearts) - to pump blood
Respiration:
- Cutaneous respiration - exchange of gases directly through moist skin
Sexual reproduction:
Excretory system:
- Nephridia - Primitive kidney; structures that eliminate metabolic wastes
Structure:

14. 14
Mollusks
- symmetry → bilateral symmetry
- coelomate
- complete digestive tract
- Mantle - membrane that surrounds the internal organs; secretes shell
- Muscular foot - used for locomotion
- Radula - a tongue-like organ with rows of teeth; used to drill, scrape, and cut food
Obtaining food:
- most use a radula to cut food into small pieces
- Bivalves are filter feeders
Sexual reproduction:
Circulation:
- have a 2-3 chambered heart
- most have an open circulatory system in which blood moves though vessels and into open spaces
around the body organs (cephalopods have a closed circulatory system).

15. 15
Open circulatory system & 2-chambered heart diagram
Respiration:
- Gills - consist of a system of projections that contain blood vessels through which gases are exchanged.
Diagram:
Gill Gill filament

16. 16
Countercurrent exchange diagram
- The transfer of a substance from a fluid moving in one direction to another fluid moving in the opposite direction.
Excretion:
- Nephridia - specialized organs for removing metabolic wastes.
Diversity:
Characteristic Gastropoda Bivalvia Cephalopoda
External shell
Head
Radula
Locomotion
Circulation
Examples

17. 17
Arthropods
- Symmetry → bilateral
- Segmented
o Head
o Thorax
o Abdomen
- coelomate
- exoskeleton
- molting
- jointed appendages
Exoskeleton:
- hard, thick, outer covering made of chitin
o protection
o Muscle attachment
o Prevent dehydration (waxy layer)
Molting:
- the shedding of the exoskeleton
o animal secretes a new soft exoskeleton
o animal sucks in air or water and splits open old exoskeleton
o old exoskeleton is discarded
o animal swells up body with increased circulation until new exoskeleton hardens
* most animals molt 4-7 times

18. 18
Gas exchange:
1. Gills - found in aquatic arthropods
2. Tracheal tubes - found mostly in insects
a. Branching hollow pipes that carry air throughout the body
b. Muscle activity helps move air through tubes
3. Book lungs - found mostly in arachnids
a. Air filled chambers that contain many folds
b. Folds are stacked and arranged like pages in a book
Sexual reproduction:
Some species exhibit _______________________________
- offspring develop from unfertilized eggs (asexual reproduction)
- ex. Wasp, aphid, bee, ant
Diversity:
1. ____________________ - 2 body regions
Ex.
2. ____________________ - 2-3 body regions
Ex.
3. ____________________ - 3 body regions
Ex.

19. 19
Metamorphosis - a series of changes, controlled by chemical substances.
a. Complete metamorphosis - larval stage is specialized for eating & growing; adult is specialized for
moving and reproducing.
- allows the insect to take advantage of more than one habitat & food source
at different life stages.
1) Egg – hatches into a larva
2) Larva – wormlike stage of an insect (caterpillar). As the larva eats and grows, it molts several
times.
3) Pupa – period of reorganization in which the tissues and organs of the larva are broken down and
replaced by adult tissues.
* Note: insect does not move or feed.
4) Adult
Ex. Beetles, flies, moths, wasps

20. 20
b. Incomplete metamorphosis - juveniles look like miniature adults
- juveniles lack wings & sexual organs
1) Egg
2) Nymph – when the insect hatches from an egg, it has the same general appearance
as the adult but is smaller.
• Note: cannot reproduce
3) Adult
Ex. Grasshoppers, cockroach

21. 21
Echinoderms
- symmetry → radial symmetry
- endoskeleton - internal skeleton
- Hard, bumpy skeleton made of calcium carbonate.
Water vascular system:
- Water vascular system - a network of water-filled canals that are connected to tube feet. The hundreds
of tube feet act like tiny suction cups.
- allows animal to climb slippery rocks and capture prey.

22. 22
Body systems:
- no circulatory, excretory, or respiratory system
o Fluid in the coelom bathes the organs and distributes nutrients and O2.
Sexual reproduction:
Structure:
Chordates
- can be classified into 3 subphyla:
o Urochordates (tunicates) Invertebrates
o Cephalochordates (lancelets)
o Vertebrates – animals with a backbone
- all chordates have 4 characteristics during some point in their life
1. Notochord - a flexible rod that gives animals support.
a. In vertebrates its remains only as part of the disks.
b. Chordates are named for this structure.

23. 23
2. Dorsal, hollow nerve cord (neural tube) - a nerve cord made from ectoderm that rolls into a hollow
tube
a. Located dorsal to the notochord
b. Ant. Becomes brain Vertebrates
c. Post. Becomes spinal cord
3. Pharyngeal pouches - develops into gill slits
4. Postanal tail - contains muscles and helps propel aquatic organisms.
Lancelet
Notochord:
- Semi rigid rod-like structure.
- Anchors internal muscles and enables invertebrate’s chordates to make rapid movements of the body
and move through water quickly.
- In invertebrate chordates, the notochord may be retained into adulthood.
- In vertebrate chordates, the notochord is replaced by a backbone.
Dorsal hollow nerve cord:
- Develops from a plate of ectoderm that rolls into a hollow tube.
Dorsal hollow nerve cord (neural tube)

24. 24
Pharyngeal pouches:
- Paired openings located in the pharynx, behind the mouth.
- In aquatic chordates, pharyngeal pouches develop openings called gill slits and gills.
- In terrestrial chordates, pharyngeal pouches develop into jaws, inner ear, and tonsils.
Postanal tail:
- In some, the postanal tail disappears during development.
- In others, the postanal tail develops into a tail fin.

25. 25
Chordate Body Plan

26. 26
Organogenesis

27. 27
Chordate evolution
A phylogenetic tree of chordates showing key derived traits

28. 28
Fishes
- Symmetry → bilateral symmetry
- Ectothermic (cold blooded) – cannot regulate their body temperature; same temp as environment.
- Coelomates
- Breathe using gills
- 2 chambered heart
- Most have paired fins
- Highly developed sensory system
3 classes of fishes:
1. Chondrichthyans (cartilaginous fish)
Ex. Sharks, rays
2. Ray-finned – have thin, skeletal rays (bones) in fins
Ex. Tuna, trout, goldfish
3. Lobe-finned – fins have heavy bones and are muscular
- have 3 lineages
a. Coelacanth – a deep sea fish
b. Lungfishes – live in stagnant waters in southern hemisphere; use primitive lung to gulp air
c. Tetrapods – adapted to life on land and gave rise to terrestrial vertebrates
Highly developed sensory system:
- Lateral line system
o Fluid-filled canals running along the sides of fish
o Allows fish to detect movement in the water.
Paired fins:
- used for balance, swimming, and steering
Heart & circulation:
- 2-chambered heart
o 1 atrium
o 1 ventricle
- Single circulation

29. 29
Single circulation diagram
Cartilaginous fish Bony fish
moveable jaws moveable jaws
scales scales
cartilage skeleton bony skeleton
paired fins paired fins
Buoyancy due to: Buoyancy due to:
1. __________________ 1. __________________
2. __________________

30. 30
Buoyancy diagram
Amphibians
(having 2 natures)
- Symmetry → bilateral symmetry
- Coelomates
- Scaleless skin through which gasses and H2O are exchanged.
- Lay eggs in water or moist places
Sensory organs:
Larva: lateral line system
Adult: smell, sight, hearing, touch
Excretion:
- use kidneys to get rid of metabolic wastes
o Larva: excrete ammonia
o Adult: excrete urea
 Convert
ammonia → urea
(very toxic) (less toxic)
needs to be diluted requires less water.
with large amounts Good strategy for
of water. land animals.
Respiration:
Larva:
1. ____________________________
2. ____________________________
Adult:
1. ____________________________
2. ____________________________

31. 31
Heart & circulation:
3-chambered heart
- Rt &Lt atria
- ventricle
Double circulation - provides faster blood flow through the body.
1. ____________________________
2. ____________________________

32. 32
3 – Chambered Heart
3-chmbered heart diagram

33. 33
Reptiles
- symmetry → bilateral symmetry
- coelomates
- dry, scaly skin, and clawed toes.
- All reptiles have 4 legs with the exception of snakes.
- Most reptiles have a 3 chambered heart, but crocodiles have a 4 chambered heart.
Scaly skin:
- Scaly skin prevents the loss of water and provides additional protection from rugged terrestrial
environment.
Reproduction:
- Reproduce by laying soft shelled eggs on land
- Most reptiles provide no care for hatchlings.
- Amniotic egg
o Provides nourishment to the embryo and contains membranes that protect it while it develops on
land.
Amniotic egg diagram

34. 34
o Encases the embryo in a secure, self-contained aquatic environment. Contains 4 membranes.
 Amnion -thin membrane enclosing the fluid in which the embryo floats.
 Yolk sac - thin membrane that encloses the yolk, a fat-rich food supply for the embryo.
 Allantois - stores wastes; also serves as the embryo’s “lung,” exchanging CO2 and O2.
 Chorion - Surrounds all the membranes and helps protect the developing embryo.
Respiration:
- Lungs - contain alveoli, small sacs that increase the surface area inside lungs.
Excretion:
- Uric acid is much less toxic than ammonia or urea. Thus, it requires little water for dilution.
Heart & circulation:
- Double circulation
- 3 chambered heart

35. 35
Aves (birds)
- symmetry → bilateral symmetry
- coelomates
- endotherms – maintain own body temperature
- 4 chambered heart
- Keeled sternum
- hollow bones
- air sacs
- beak
- feathers (unique to birds)
Heart & circulation:
- more efficient than a 3-chambered heart, because it prevents mixing of blood from the 2 circulation
loops.

36. 36
Keel-shaped sternum:
- needed to support the enormous thrust and power produced by the flight muscles
Hollow bones:
- Hollow bones, strengthen by bony crosspieces, allow for both strength and lightweight.
Air sacs:
- The high metabolic rate of birds requires large amounts of oxygen.
- Have anterior sacs, posterior sacs, and lungs. Sacs are not used for gas exchange.
- Breathing mechanism allows bird to have oxygenated air in its lungs during both inhalation and
exhalation.
Breathing mechanism diagram

37. 37
Beaks:
- sometimes called bills
- covered by a protein called keratin
- do not have teeth
Feathers:
- A lightweight, modified protein scale that provides insulation and enables flight.
Reproduction:
- internal fertilization
- amniotic egg
- Eggs are encased in a hard shell.
Digestion:
- Have no teeth, so food is swallowed whole.
Excretory system:
- Need to maintain a lightweight, so no liquid waste is stored. (no bladder)
- Uric acid is filtered from the blood by kidneys, then travels to the cloaca, where it is mixed with
undigested feces.
- Bird droppings are a mixture of feces and uric acid.
Origin of birds:
- Fossil finds in China support the idea that birds evolved from a dinosaur.

38. 38
Mammals
- symmetry → bilateral symmetry
- coelomates
- endotherms
- internal fertilization
- 4-chambered heart
- Diaphragms – thin sheet of muscle that separates chest from abdomen
- hair
- produce milk to nurse their young.
- specialized teeth
- highly developed brains.
Diaphragm:
- helps expand the chest cavity to aid the flow of air into the lungs
Hair:
- Hair is present on all mammals at some point in their lives.
- Made out of the protein keratin
- Provides insulation and waterproofing and thereby conserves body heat.
- Mammals cool off by panting and sweating.
Produce milk:
- Feed their young from mammary glands which produce and secrete milk, a liquid that is rich in fats,
sugars, proteins, minerals, and vitamins. Mammals nurse until the young are able to digest and absorb
nutrients from solid foods.

39. 39
Specialized teeth:
- Have different kinds of teeth that are adapted to the type of food the animal eats.
Highly developed brains:
- One major reason mammals are successful is that they guard their young and teach them survival skills.
Mammals can accomplish complex behaviors, such as learning and remembering what they have
learned.
Mammal classification:
- Mammals are classified into subclasses based on how they reproduce:
o Placentals
 Give birth to young that have developed inside the mother’s uterus until their body
systems are fully functional.
 90% of all mammals are placentals
o Marsupials
 A marsupial is a mammal in which the young have a short period of development within
the mother’s body, followed by a period of development inside a pouch made of skin and
hair on the outside of the mother’s body.
 Ex. Kangaroo, possum
o Monotremes
 Reproduce by laying eggs
 Ex. Platypus

40. 40
Metabolic Wastes, Thermoregulation, Reproduction
Metabolic wastes:
Aquatic animals Terrestrial animals
ammonia urea
/ uric acid
lots of water some water little water
liquid liquid paste
high toxicity medium toxicity low toxicity
lots of space some space little space
* animals that do not * animals that do produce
produce shelled eggs shelled eggs
Thermoregulation:
Ectothermy vs. Endothermy
Characteristic Ectothermy (cold blooded) Endothermy (warm blooded)
Heat source
Metabolism
Sweat
Energy
Exertion
Food consumption
Climate
Examples