Animal Diversity - Ch. 27

Question 1

Edicaran biota

Answer 1

evolved around 635-543 mya - time before the cambrian explosion
may have evolved from protists
were only a few mm or cm long

Question 2

Cambrian explosion

Answer 2

includes animals with multiple body parts that are similar to today
is 542-488 mya
animals were similar to echinoderms, molluks, worms, anthropoda, and chordates
dominate species during this time was the trilobite, which was an arthropod which may have been able to see.
thousands of species from this period but none are alive

Question 3

Mesozoic era

Answer 3

251-65.5 mya
coral reefs evolved, becoming an important marine ecological niches for other organisms
plesiosaurs were reptiles that returned to water
dinosaurs were the dominant terrestrial vertebrates
first mammals appear
flowering plants and insects diversified

Question 4

Cenozoic era

Answer 4

65.5 mya - present
beginning of the era marked by a mass existinction of both terrestrials and marine animals
mammals increased in size and exploited vacated ecological niches
the global climate cooled

Question 5

cell structure of animals

Answer 5

animals are multicellular eukaryotes
cells lack cell wall
bodies are held together by structural proteins such as collagen
nervous tissue and muscle tissue are unique, defining characteristics of animals

Question 6

diploblastic

Answer 6

animals that have an ectoderm and an endoderm

Question 7

triploblastic

Answer 7

animals have an intervening mesoderm layer

Question 8

endoderm

Answer 8

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

Question 9

ectoderm

Answer 9

the germ layer covering the embryos surface

Question 10

radial symmetry

Answer 10

no front or back, and no left or right

typically are sessile animals, often drifting or swimming weakly

Question 11

asymmetrical symmetry

Answer 11

having no symmetry

Question 12

bilateral symmetry

Answer 12

two sided symmetry
have a dorsal (top) and a ventral (bottom), a right and left, and an anterior (head) and posterior (tail)
cephalization
bilateral animals typically move actively and have a central nervous system

Question 13

coelom

Answer 13

term used to describe a fluid filled cavity or space
placental vertebrates develop both extraembryonic and intraembryonic coeloms
instraembryonic coelom is intially a single space located in the mesoderm, which will later form the major body cavities

Question 14

pseudocoelomates

Answer 14

any group of invertebrates with a three layer body that has a bluid filled body cavity between the endoderm and the mesoderm

Question 15

acoelomates

Answer 15

animals that lack a body cavity

Question 16

cleavage pattern of protostomes

Answer 16

spiral and determinate

Question 17

protostomes

Answer 17

the blastopore becomes the mouth

Question 18

tissues in gastrulation

Answer 18

gastrulation is when the tissues form

-stage of the embryo with two or three cell layers

Question 19

what is the nutritional mode of animals?

Answer 19

they are heterotrophs

Question 20

what is the reproduction and development modes of most animals?

Answer 20

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

Question 21

cleavage pattern of deuterstomes

Answer 21

radial and indeterminate

Question 22

deuterostomes

Answer 22

the blastula becomes the anus

Question 23

blastula

Answer 23

an early development of an embryo, consisting of a spherical cell layer and a fluid filled cavity