Chapter 23 animals

Question 1

8 major characteristics that are common to all animals

Answer 1

heterotrophs, multicellular, no cell walls, most can move, diverse form and habitat, most produce sexually, embryotic development, cells organized into tissues (except sponges)

Question 2

Tissues

Answer 2

Parazoa(sponges)- lack defined tissues and organs, can disaggregate and aggregate their cells
Eumetazoa(all other animals)- distinct well-defined tissues, irreversible differentiation for most cells
(allows for better response to enviroment-evolution of more complex organs)

Question 3

Symmetry

Answer 3

sponges lack symmetry, eumetazoa- defined symmetry along an imaginary axis.
Radial- central axis Bilateral- down the middle, advantages= cephalization and greater mobility.

Question 4

Body cavity

Answer 4

Space surrounded by mesoderm tissue that is formed during development (allows for complex phisiology and reproductive strategies)

Question 5

3 germ layers (body cavity)

Answer 5

Eumetazoa- ectoderm(body coverings and nervous system), mesoderm(skelenton and muscles), endoderm(digestive organs and intestines)

Question 6

3 body plans

Answer 6

Acoelomates(no body cavity), pseudocoelomates(body cavity between mesoderm and endoderm-pseudocoel), coelomates(body cavity in mesoderm-coelom)

Question 7

Circulatory sytems

Answer 7

developed by coelomates to flow nutrients and remove waste.

Question 8

Open circulatory sytem

Answer 8

blood passes from vessels into sinuses, mixes with body fluids and reenters the vessels

Question 9

Closed circulatory sytem

Answer 9

blood moves continuously through vessels that are separated from body fluids

Question 10

Development

Answer 10

(allows for wide varaity of forms and distinct groups)

Question 11

Bilateral pattern of development

Answer 11

Mitotic cell divisions of the egg forms a hollow ball of cells, called the blastula, Blastula indents to form a two-layer-thick ball with: Blastopore = Opening to outside-Archenteron = Primitive body cavity

Question 12

Protostomes

Answer 12

group of bilaterians that develop the mouth first from or near the blastopore-Anus (if present) develops either from blastopore or another region of embryo, Determinate development (type of tissue each embryonic cell will form in adult is predetermined early on – can’t separate and differentiate)

Question 13

Deuterostomes

Answer 13

Indeterminate development (type of tissue each embryonic cell will form in adult is not predetermined at early stages – can separate and differentiate)

Question 14

Segmentation

Answer 14

provides 2 advantages- redundant organ systems in adults such as kidneys occurs in the annelids and more efficient and flexible movement each segment can move independently.
(segments can be adapted for diffrent functions leading to high diversity)

Question 15

Be able to map each of the five transitional characters onto a phylogeny
(i.e., given a phylogeny or a question about which animals possess a given character, be able to map the character or state which animals possess it).

Question 16

why animal taxonomy is being revised

Answer 16

key morphological characters used in traditional classification are not necessarily conservative and always reciving new data

Question 17

Metazoans

Answer 17

multicellular animals

Question 18

2 main branches of metazoans

Answer 18

Parazoa = Lack symmetry and tissues
Eumetazoa = Have symmetry and tissues
and
Diploblastic = Have two germ layers
Triploblastic = Have three germ layers

Question 19

Molecular systematics

Answer 19

uses unique sequences within certain genes to identify clusters of related groups

Question 20

irreversible differentiation

Answer 20

a process during development in which a cell becomes committed to a specific function the cell cannot revert to its original state.