1. Animals
Chapter 25

2. Common Characteristics of all animals:
Multicellular
Eukaryotes
Have membranes around organelles
No cell walls or chloroplasts
Get food by feeding on other animals
Heterotrophs
Move based on the way they obtain food
Sessile-animals that don’t move (ex. Sea Urchin)
Digest food
3 steps of digestion:
Break down food
Use food for energy
Store excess food as glucose/glycogen

3. Development overview:
All animals have the same development process
Zygote cleavage (splitting of the cell)

4. Gastrula formation

5. Layers of gastrula (germ layers)
Ectoderm- (outside layer)
Forms skin, nerves, smaller vessels
Mesoderm-(middle layer)
Forms muscles,
Large Blood vessels,
reproductive organs
Endoderm- (innermost layer)
Forms digestive tract and organs

6. Animal development cont…
Protostome- opening in the indented space becomes a mouth
(lower organisms)
Deutorostome-opening in the indented space becomes on anus and the mouth forms from cells elsewhere
(higher animals like mammals)

7. Coelom- body cavity completely surrounded by a mesoderm/lining
Ex. Human, higher organisms

8. types of body cavities Acoelomate (no coelem) Pseudocoelomate-
Has all the layers of development but no cavity for organs
Has 1 opening to body
Pseudocoelomate-
has all 3 layers of development, a digestive tract and fluid filled cavity (coelem) for organs
Has 2 body openings
Coelomate-
has the 3 layers and a digestive tract and fluid filled cavity (coelem)
*also has a membrane attached to the organs

9. 3 symmetries of animals:

10. Symmetry of animals: Symmetry- balance of an animals body proportions
3 kinds of symmetry:
1. asymmetry (no balance)-
Body is irregular shaped
Cannot cut it anywhere and make the halves balance
Includes sessile organisms (don’t move)

11. Symmetry types cont…
2. radial symmetry- body can be divided into equal halves by cutting at multiple locations (ex. Hydra)
3. bilateral symmetry- can cut the body into equal halves at 1 location
The halves are mirror images
These organisms move very efficiently
Ex. Man, mammals, birds

12. Animal protection and support:
skeleton- protects and supports
2 kinds of skeletons in animals:
Exoskeleton- on the outside of body
Hard waxy covering
In insects, the skeleton is made of chitin
Molting-shedding of exoskeleton
Endoskeleton- skeleton within-supports body and protects organs

13. Animal protection and support cont…
There are 2 types of organism groups based on if they have a backbone
1.Vertebrates- have a backbone
2. Invertebrates- no backbone
If an animal has an exoskeleton, it cannot have backbone

14. Body direction terms: Dorsal-toward the back
Ventral-toward the stomach

15. Body terms cont… Posterior-toward the tail/back Superior-above
Inferior-below
Anterior-toward the front