Ch 32 an overview of animal diversity

Question 1

How many living animal species have scientists identified?

Answer 1

1.3 million

Question 2

How do we distinguish animals from other life forms?

Answer 2

Animals are multicellular, heterotrophic eukaryotes with tissues that develop from embryonic layers.

• Their cells lack cell walls
• their bodies are held together by structural proteins such as collogen
• nervous tissue and muscle tissue are unique, defining characteristics of animals

Question 3

Explain reproduction and development of animals

Answer 3

• most animals reproduce sexually, with the diploid stage usually dominating the life cycle
• after the sperm fertilizes an egg, the zygote undergoes rapid cell division called cleavage
• cleavage leads to formation of a multicellular hollow blastula
• the blastula undergoes gastrulation, forming a gastrula with different layers of embryonic tissues

Question 4

What is a larva stage? and a metamorphosis?

Answer 4

a larva is sexually immature and morphologically distinct from the adult; it eventually undergoes metamorphosis (adult stage)

Question 5

What is an example of an animal of the earliest fossil record?

Answer 5

a sponge

Question 6

What is the endiacaran biota?

Answer 6

it is one of the earliest fossil records for multicellular organisms which date fom 565 to 550 million years ago.

Question 7

What happened to the endiacarans after the cambrian explosion?

Answer 7

They went extinct however all the phyla we see today came from the cambrian explosion.

we lost a lot of phyla but there hasnt really been any new ones

Question 8

What re some hypothesis regarding the cause of the cambrian explosion and decline of ediacaran biota?

Answer 8

• New predator-prey relationships
• a rise in atmosphere oxygen
• the evolution of the hox gene complex

Question 9

When did animals make an impact on land and how?

Answer 9

by 460 million years by having animals have both gils and lungs allowing them to be both on land and sea.

Question 10

When did vertebrates make the transition to land?

Answer 10

360 million years ago

Question 11

What occurred during the mesozoic era?

Answer 11

• coral reefs emerged in 251-65.5 million years ago becoming important marine ecological niches for other organisms
• dinosaurs were the dominant terrestial vertebrates of that time
• the first mammals emerged
• flowering plants and insects diversified

Question 12

what events occurred in the cenozoic era?

Answer 12

• the beginning of the cenozoic era followed mass extinctions of both terrestrial and marine animals
• these extinctions included the large, nonflying dinosaurs and marine reptiles
• mammals increased in size and exploited vacated ecological niches, there was gigantism among rodents
• the global climate cooled

Question 13

What is symmetry?

Answer 13

How things are place, symmetry allows for us to dstinguish good genes from the bad “health”

Question 14

What is the difference between radial symmetry and bilateral symmetry? give an example of each

Answer 14

radial symmetry is used to describe an animal that has no front, back, or left or right side

ex: a sea anenimy, jelly fish

bilateral symmetry indicates an animal that has a left and right side such as a human or a dog

Question 15

What is planktonic?

Answer 15

radial animals are planktonic which mean that they usually stick to something and swim slowly

Question 16

What are the colors for ectoderm and endoderm?

Answer 16

ectoderm is blue

endoderm is yellow

and mesoderm is red

Question 17

is there a multicellular animal who doesnt have tissue?

Answer 17

yes, sponges, they are precursors to tissues

Question 18

What is an ectoderm?

Answer 18

the ectoderm is the germ layer covering the embryos surface

Question 19

What is the endoderm?

Answer 19

it is the innermost germ layer and lines the developing digestive tube, called the archenteron

Question 20

What is the first archenteron formed inside of humans?

Answer 20

The gastrulation and then the opening (anus)

Question 21

What do diploblastic animals have and give examples

Answer 21

they have ectoderm and endoderm

-these include cnidarians and comb jellies

Question 22

What are triploblastic animals?

Answer 22

animals that have an intervening mesoderm layer; these include all the bilaterians

-these include flatworms, arthropods, vertebrates, and others

most triploblastic animals posses a body cavity

Question 23

what is a coelom? and what is its function?

Answer 23

A coelom is a body cavity a coelom is a space surround by mesoderm. It is used as a sort of cushion for the inner organs. It also allows for the body to bend and move around without possibly harming your inner organs. Also it allows for your organs to expand

Question 24

What are coelomates?

Answer 24

They are animals that posses a true coelom, such as earthworms have a true coelom, a body cavity lined by tssue derived from mesoderm

Question 25

What are pseudocoelomates?

Answer 25

pseudocoelomates such as roundworms have a body cavity lined in part by tissue derived frommesoderm but also from endoderm

Question 26

what are acoelomates?

Answer 26

acoelomates such as planerians, lack a body cavity between the digestive cavity and the outer body cavity.