Animal Features

Ch. 44-47

1. muticellular heterotrophs

2. forms

a. invertebrates: lacking a backbone

b. vertebrates: true backbone

3. no cell walls: all but sponges have distinct tissues

4. active movement: flexible cells/development of nervous system

5. sexual reproduction: no alternating generations. Gametes fuse thenà mitosis

6. embryonic development

a. morula; solid ball of cells

b. blastula; hollow ball of cells.

c. gastrula; Blastopore forms in most to form another cavity (digestive system)

7. classification of animals

a. parazoa: no definite form/tissues=songes (porifera)

b. eumetazoa: symmetry/tissue layers

i. ectoderm:

diploblastic

ii. endoderm triploblastic

iii. mesoderm

body plan of animals

1. distinct tissue types:

a. parazoa lack tissue types: sponges

b. eumetazoa: cnidaria, platyhelminthes, nematoda, rotifer, mollusca, annelida, arthropoda, echinidermata, chordata

2. symmetry:

a. no symmetry: sponges

b. radial symmetry: radiata(cnidaria & ctenophores)

c. bilateral symmetry: platyhelm., nematod.,rotieria.,mollusca, annelida, arthropoda, echinoderms, chordata.

i. Evolutionary advantages: more efficient movement, cephalization, organization of organs, locating mates, avoiding predation.

3. body cavity

a. acoelomates: no body cavity (except for digestive cavity surrounded by endoderm)

b. pseudoceolomates: false body cavity lined by mesoderm and endoderm.

c. Coelomates: true cavity surrounded by mesoderm.

i. Gives rise to a compartment for digestive/reproductive organs

ii. Requires circulation of nutrients that cant just diffuse to cells now.

1. open circulatory system: vessels and sinuses send nutrients to cells.

2. closed circulatory system: vessels and hearts separate and move blood to make more effective delivery of nutrients.

iii. Primary induction allows for the development of complex organ systems.

1. necessary for endoderm and mesoderm to be in direct contact during embryologic development.

4. deuterostomes/protostomes

a. coelomates:

i. protostomes: blastopore becomes mouth. Examples include:mollusca, annelida, arthropoda.

ii. Deuterostomes: blastopre becomes anus. Examples include: echinodermata, chordata.

5. segmentation

a. increase efficiency

i. movement can be controlled by section

ii. damage to one segment isn’t fatal

iii. metamerism: present