1. Characteristics of Animals
Chapter 25

2. General Characteristics of Organisms Found in the Animal Kingdom
Animals are eukaryotic, multicellular, heterotrophic organisms.

3. Not all animals have the ability to move to find food or capture their prey.
Organisms that are permanently attached to a surface are known as sessile.

4. Digestion in Animals Once food has been ingested it must be digested.
Some organisms do not have a complete digestive tract.
Their food enters and waste exits through the same opening.

5. Fertilization Most animals reproduce sexually.
Fertilization of egg cells may be internal or external.
-internal
-External

6. The 3 Embryonic Germ Layers of Animal Development
Most animals develop from a fertilized egg cell called a zygote.

8. Once fertilization has occurred, the zygote begins rapidly dividing.
A blastula is the hollow fluid filled ball of cells that is the result of the cell division of the zygote.
A gastrula is the structure that forms from a blastula as the cells on one side move inward forming an opening.
During gastrulation a third layer of cells is added to most embryos known as mesoderm.

9. Germ Layers Form the tissues, organs, & systems of an animal
Ectoderm (outer) forms skin, nerves, & sense organs
Endoderm (inner) forms the digestive & respiratory organs & systems
Mesoderm (middle) forms muscles, circulatory system, reproductive & excretory systems

15. protostomes
In animals where the opening of the gastrula develops into the mouth are known as protostomes. (snails, earthworms, and insects)

16. Deuterostomes
Animals that develop a mouth from cells in the gastrula rather than the opening are called deuterostomes. (fish, birds, and humans)

18. 3 Forms of Symmetry in Animals
Symmetry describes the arrangement of body structures of animals. (Asymmetry, Radial, Bilateral)
Asymmetry -If an animal has an irregular shape or no symmetry to its body plan.

19. Radial Symmetry
Animals that can be divided along any plane, through a central axis, into equal halves.

20. Bilateral Symmetry
Animals that can be divided lengthwise into equal right and left halves.

21. Anatomical Directional Terms
Ventral = the belly or under side of an animal
Dorsal = the back or top side of an organism
Anterior = towards the head end
Posterior = towards the tail end or away from the head
Proximal = towards the body where an appendage joins the body
Distal = away from the body towards the end of an appendage
Caudal = synonym for posterior
Cranial = relating to the skull or cranium

22. Anatomical Directional Terms

23. Anatomical Directional Terms

24. Body Plan
Body cavities are fluid-filled spaces inside an organism where the internal organs are often found.
1) Acoelomate = the simplest body plan, 3 germ layers but no body cavity
2) Pseudocoelomate = has a fluid-filled body cavity between endoderm and mesoderm = pseudocoelom
The internal organs are actually found free within pseudocoelom
3) Coelomate = has body cavity & specialized organs that develop in coelom
Found in humans, insects, fishes

25. 3 Animal Body Plans
1) Acoelomate = animals that develop from the 3 cell layers but have no body cavities.
They have a digestive tract throughout their body
Ex. Flatworms

26. 3 Animal Body Plans
2) Pseudocoelomate = animals with a fluid filled body cavity that is partially lined with mesoderm
They have a one-way digestive tract with regions of specific functions
Ex. Earthworms

27. Pseudocoelomate

28. 3 Animal Body Plans
3) Coelomate = animals that have a true fluid filled body cavity completely surrounded by mesoderm that contains internal organs
They have internal organs and a digestive tract attached by mesoderm and suspended within the coelom
Ex. Humans and Fish

29. Coelomate

30. Ectotherm Vs. Endotherm
Ectothermic- animal that has a variable body temperature and derives its heat from external sources.
Ex) Snake
Endothermic- Animal that maintains a constant body temperature and is not dependant on environmental temperature.
Ex) Cat

31. Ectothermic

32. Endothermic