chapter 27

Question 1

filter feeders (sponges)

Answer 1

capture food particles suspended in the water that passes through their bodys

Question 2

tissues

Answer 2

groups of cells that function as a unit

Question 3

choanocytes

Answer 3

flagellated collar cells generate a water current through the sponge and i get suspended food.

Question 4

amoebocytes

Answer 4

mobile cells that play roles in digestion and structure

Question 5

cnidarians

Answer 5

have no tissue. wide range of both sessile and mobile forms. still no brains but have noncetralized nerve net associations with sensory structure distributed throughout the body.

Question 6

cambrian explosion

Answer 6

marks the earliest fossil appearance of many major groups of living animals. most were bilaterians

Question 7

bilaterians

Answer 7

a clade whose members have a complete digestive tract and a bilaterally symmetric form

Question 8

gastrovascular cavity

Answer 8

the basic body plan of a cnidarian is a sac with a central digestive compartment. both mouth and anus

Question 9

cambrian explosion theories:

Answer 9

new predator prey relationships
a rise in atmospheric oxygen
the evolution of the Hox gene complex

Question 10

body plan

Answer 10

a set of morphological and developmental traits. three important aspects: symmetry, tissues, body cavities.

Question 11

radialsymmetry

Answer 11

no front/back or left/right symmetry. usually sessile or planktonic.

Question 12

bilateral symmetry

Answer 12

two-sided symmetry (top/bottom, right/left, head/tail)

Question 13

ectoderm

Answer 13

germ layer covering the embryos surface

Question 14

endoderm

Answer 14

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

Question 15

mesoderm

Answer 15

third germ layer that fills the space between the endoderm and the exoderm in all bilaterally symmetric animals

Question 16

body cavity (coelomates)

Answer 16

a fluid or air-filled space between the digestive tract and the outer body wall. cushions suspended organs, acts as a hydrostatic skeleton, enable internal organs to move independently of the body wall.

Question 17

chordata

Answer 17

the only phylum that includes vertebrates, animals with backbone

Question 18

lophotrochozoa

Answer 18

bilaterian clade that primarily defined by molecular data

Question 19

exdysozoa

Answer 19

bilaterian clade that is defined by shedding a cuticle covering

Question 20

decterostomia

Answer 20

a bilaterian clade that’s mouth forms from the second opening formed in early embryo development

Question 21

arthropods

Answer 21

two out of every species known. insects are most diverse. body plan consists of a hard exoskeleton made of layers of protein and the polysaccharide chitin joined apperdaya

Question 22

four key derived characters of chordates:

Answer 22

-notochord: flexible rod providing support
-dorsal hollow nerve cord
-pharyngeal sits or pharyngeal clefts which function in filter feeding as gills or as part of the head
-muscular post-anal tail

Question 23

gnathostomes

Answer 23

law vertebrates. diverged from chorndrichthyans. ray-finned fishes and lobe-fin.

Question 24

chrondrichthyans

Answer 24

sharks rays and relatives. composed of mostly cartilage and has some of the most successful aquatic animals.

Question 25

ray-finned fishes

Answer 25

nearly all the familiar aquatic osteichthyans

Question 26

lobe-fins

Answer 26

major lineage of osteichthyans. have rod-shaped bones surrounded by a thick layer of muscle in their pectoral and pelvic fins. consist of coelacanths, lungfish, and tetrapods

Question 27

tetrapods

Answer 27

terrestrial vertebrates with limbs/digits

Question 28

amphibians

Answer 28

salamanders, frogs caccilians. restricted to moist areas within terrestrial habitats. moist skin helps breathe. aquatic external fertilization

Question 29

amniotes

Answer 29

group of tetrapods whose living members are the reptiles including birds and mammals. known for amniotic egg which contains membrane that protects embryo.

Question 30

reptiles

Answer 30

one living linage of amniotes. most have scales that create a waterproof barrier. many lay eggs on land. most are ectothermic

Question 31

ectothermic

Answer 31

absorbing external heat as the main source of body heat

Question 32

endothermic

Answer 32

capable of keeping the body warm through metabolism

Question 33

mammals

Answer 33

extant lineage of amniotes. have hair/differentiated teeth. many glands that produce milk

Question 34

monotremes

Answer 34

egg-laying

Question 35

marsupials

Answer 35

mammals with pouch

Question 36

eutherians

Answer 36

placental animals