Chapter 27 - Part 1

Question 1

All but the simplest animals have specialized _, _, and _, systems that make them highly effecting eating machines.

Answer 1

Muscle
nervous
digestive

Question 2

Animals life began in the ocean with small, _ _ species about 560 MYA.

Answer 2

soft - bodied

Question 3

How many animal species are there today?

Answer 3

8 million species

Question 4

What are the most basal (base) and simple modern-day animal group?

Answer 4

Sponges
Phylum Porifera

Question 5

What is the earliest group to have diverged from all other animals?

Answer 5

Porifera (sponges)

Question 6

List the characteristics of Sponges:

Answer 6

1. Lack true tissues
2. all are aquatic, most are marine
3. sessile (immobile) filter feeders
4. can be super small or super big

Question 7

What animal diverged from all other animals after the sponges and list some examples.

Answer 7

Cnidarians
Jellies,
sea anemonies

Question 8

List the characteristics of Cnidarians:

Answer 8

1. Eumetazoans - true animals since they have tissues
2. all are aquatic, most are marine
3. Radial body plan (think cutting it like a pizza)
4. some are mobile (medusa), others are sessile (polyp)
5. All carnivores with a gastrovascular activity
6. no brain but have simple muscles and nerves

Question 9

What is a gastrovascular cavity?

Answer 9

one compartment that functions as both mouth and anus, where all digestion occurs. Pre-cursor to a true digestive system.

Question 10

List some examples of Cnidarians

Answer 10

1. Hydrozoa (colonial polyps)
2. Scyphozoa (jellyfish)
3. Anthozoa (sea anemones)

Question 11

What was the Cambrian explosion?

Answer 11

when the diversity of animals increased dramatically 525-535 MYA.

Question 12

What happened in the Cambrian explosion?

Answer 12

1. the new species were bilaterians
2. have a complete digestive tract
   3.when ancestors of modern-day chordates and arthropods appear

Question 13

what are chordates?

Answer 13

vertebrates

Question 14

List the 3 types of symmetry

Answer 14

1. none
2. radial
3. bilateral

Question 15

Why did the rise of bilaterian life-forms coincided with a decline in earlier life forms?

Answer 15

the evolution of armor and weapons

Question 16

List the characteristics of earlier life forms

Answer 16

1. soft bodied
2. not predatory (grazers, filter feeders or scavengers)

Question 17

What did the new predators emerge with?

Answer 17

1. defensive hard bodies, shells, sharp pines
2. offensive adaptations - claws, grasping limbs

Question 18

What do majority of bilaterians have?

Answer 18

Mobility, nervous system and digestive tracts that made them dangerous feeding machines

Question 19

The Cambrian explosion was huge for the evolution of diverse forms of animals in the __.

Answer 19

Ocean

Question 20

What characteristics did the animals in the early oceans have?

Answer 20

1. morphology (body form)
2. ecology (way of life)
3. taxonomic affiliation (type of animal group)

Question 21

What is a body plan?

Answer 21

a particular set of morphological and development traits that are integrated into a functional whole - the living animal

Question 22

What are the 3 important aspects to an animal’s body plan?

Answer 22

1. Symmetry
2. tissue organization
3. body cavities

Question 23

The symmetry of an animal fits it __.

Answer 23

lifestyle

Question 24

Why does radial symmetry work for some animals?

Answer 24

because they are sessile or planktonic (drifting or weakly swimming) and this allows them to meet their environment equally from all sides

Question 25

Why is bilateral symmetry important for some animals?

Answer 25

because they have sensory equipment that is concentrated at the anterior (front) and this enables them to move directionally to fly, swim, crawl, burrowing

Question 26

What are the 3 types of tissue organization in animal body plans?

Answer 26

1. ectoderm
2. endoderm
3. mesoderm

Question 27

What is ectoderm?

Answer 27

outermost germ layer which gives rise to the outer covering of the animal and the central nervous system.

Question 28

what is endoderm?

Answer 28

innermost layer - gives rise to the digestive organs and respiratory organs

Question 29

What is the mesoderm?

Answer 29

everything else the in between layer - gives rise to all the other organs between the outer covering of an animal’s digestive tract.

Question 30

list some examples of mesoderm

Answer 30

muscles, bones, circulatory system

Question 31

How many germ layers do Porifera have?

Answer 31

zero since they have no true tissues

Question 32

how many germ layers do cnidarians have?

Answer 32

2
endoderm and ectoderm

Question 33

how many germ layers do Bilaterians have?

Answer 33

All three

Question 34

Having all 3 germ layers is referred to as

Answer 34

trioploblastic

Question 35

What do most bilaterians have?

Answer 35

a body cavity called a coelom

Question 36

what is a coelom?

Answer 36

fluid or air filled space between the digestive tract and the outer body wall.

Question 37

where does the coelom develop from?

Answer 37

mesoderm

Question 38

What are the 3 functions of the coelom?

Answer 38

1. cushions organs
2. hydrostatic skeleton
3. independent movement

Question 39

what is hydrostatic skeleton?

Answer 39

for animals with a soft body, non-compressible fluid against which muscle can work