Chapter 23 Animal origins and Diversity

Question 1

What are the general characteristics of Animals?

Answer 1

Multicellularity
Motility
Heterotrophy
Internal digestion
*These are not diagnosit for all animals

Question 2

What are the synamorphologies of animals

Answer 2

Unique junctions between cells
Common set of extracelluar molecules, including collagen and proteoglycans
Similarities in Hox and other developmental genes

Question 3

What are Hox genes?

Answer 3

Hox genes (a subset of homeotic genes) are a group of related genes that control the body plan of an embryo along the cranio-caudal (head-tail) axis

Question 4

What was the common ancestor of animals

Answer 4

Probably a colonial flagellated protist - similar to existing choanoflagellates and sponges

Question 5

Why did colonies probably occur

Answer 5

Because they are more effective at prey capture

Question 6

What developmental patterns can be seen in animals

Answer 6

Diploblastic - animals that have 2 cell layers - ectoderm and endoderm

Triploblastic - animals that have 3 cell layers - ectoderm, endoderm and mesoderm

Question 7

What is granulation

Answer 7

Embryo is ahollow ball of cells that indents to form a cavity (blastospore)

Question 8

What are the 2 divisions of tripoblastic animals

Answer 8

Protosomes - blastospore develops into mouth

Deuterostomes - blastospore develops into anus, mouth develops later

Question 9

What are the 4 key features of body plan in animals

Answer 9

Symmetry
Body cavity structure
Segmentation
External appendages

Question 10

What are the 2 types of symetry

Answer 10

Radial symmetry - body parts arranged around cental axis

Bilateral symetry - one plane of symetry

Question 11

What is cephalization

Answer 11

concentration of sensory organs and nerve tissue at anterior end or head

Question 12

What are the 3 types of body cavity structure

Answer 12

Acoelomate
Pseudocoelomate
Coelomate

Question 13

Describe the body cavity structure of Acoelomate

Answer 13

lacks fluid filled body cavity (e.g. flatworm)

Area between gut and body wall is filled with mesenchyme (Cells)

Question 14

Describe the body cavity structure of Pseudocoelomate

Answer 14

Pseudocoel body cavity, fluid filled space in which organs are suspended.
- Pseudocoel only on outside, mesoderm surrounds internal organs

Question 15

Describe the body cavity structure of Coelomate

Answer 15

(Mammals)
Body cavity is coelom that develops with mesoderm
- Layer of muscular tissue (peritoneaum) lines the coelom and surrounds internal organs

Question 16

What is the role of segmentation in organ specialty?

Answer 16

Facilitates special

Question 17

What is the significance of segmentation in animals?

Answer 17

Allows for specialization of areas

Allows animals to alter body shape and cotrol movement

Question 18

What are appendages

Answer 18

Antennae, claws, mouthparts and reproductive orans

Question 19

How does the nervous system of bilaterans differ to some others, such as jellyfish

Answer 19

Bilaterans have well-coordinated central nervous system

Jellyfish have diffuse nervous system called nerve net