Lecture 4

Question 1

in what type of animals do body cavities exist?

Answer 1

-triploblastic animals

Question 2

what are the 3 grades of body cavities?

Answer 2

-(eu)coelomates
-pseudocoelomates
-acoelomates

Question 3

what is a (eu)coelomates body cavity?

Answer 3

-full cavity completely lined with mesoderm
-closed circulatory system

Question 4

what phylums have a (eu)coelomate body cavity?

Answer 4

-annelids
-chordates
-echinoderms
-molluscs
-arthropods

Question 5

what is a pseudocoelomate body cavity?

Answer 5

-false cavity only partially lined by tissue derived from the mesoderm

Question 6

what phylum has a pseudocoelomate body cavity?

Answer 6

-nematodes

Question 7

what is a acoelomate body cavity?

Answer 7

-no body cavity (not completely formed)
-no space between tissue layers

Question 8

what phylum has a acoelomate body cavity?

Answer 8

-platyhelminthes

Question 9

what does the lophotrochozoa clade feature?

Answer 9

-animals with a wide range of body forms
-contains bilaterian animals
-have a lophophore
-have a trochophore larva form

Question 10

what is a lophophore?

Answer 10

-feeding structure in aquatic organisms

Question 11

what is a trophophore larva form?

Answer 11

-common larval form
-simple
-3 tissue systems
-complete gut (coelomate)

Question 12

what bilaterian animals are found within the lophotrochozoa clade?

Answer 12

-coelomates (full cavity with a digestive tract and 2 openings)
-ex: annelids, molluscs, brachiopods, rotifers, and flatworms

Question 13

what are the 4 common structures within the mollusca phylum?

Answer 13

-muscular foot
-mantle
-radula
-visceral mass

Question 14

what is the purpose of the muscular foot?

Answer 14

-helps with movement, digging, and capturing prey

Question 15

what is the mantle and what is its purpose?

Answer 15

-water filled chamber containing gills (or lungs), anus, and excretory pores
-produces the shell

Question 16

what is the purpose of the radula?

Answer 16

-functions as a tongue to capture food

Question 17

what is the purpose of the visceral mass? why is it pushed in?

Answer 17

-houses internal organs
-pushed in b/c of the large foot

Question 18

what are the 4 major classes of molluscs?

Answer 18

-gastropods
-bivalvia
-polyplacophora
-cephalopoda

Question 19

what are the key features of the gastropod class? what are examples?

Answer 19

-1 piece shell
-use radula to feed off plants + algae
-ex: snails + slugs

Question 20

what are the key features of the bivalvia class? what are examples?

Answer 20

-2 piece shell
-no distinct head
-suspension feeders
-sedentary lives
-ex: clams, oysters, and other bivalves

Question 21

what are the key features of the polyplacophora class? what are examples?

Answer 21

-many piece shell
-scrape algae from rocks
-ex: chitons

Question 22

what are key features of the cephalopoda class? what are examples?

Answer 22

-intelligent animals
-can camouflage
-use tentacles to grasp prey
-ex: squids, octopuses, and cuttlefish

Question 23

what are the key aspects of the annelida phylum?

Answer 23

-segmented worms
-live in water or damp soil
-have compartmentalized organs
-have a true body cavity + complete gut
-have a trochophore larva stage (undergo metamorphosis)

Question 24

what are the 2 clades within the annelida phylum?

Answer 24

-errantia
-sedentaria

Question 25

what are the key aspects of the errantia clade?

Answer 25

-active -mostly marine -predators or grazers (plant feeders) -2 appendages

Question 26

what are the 2 appendages found within the errantia clade?

Answer 26

-parapodia -palps

Question 27

what are parapodia used for? how many are present in each organism?

Answer 27

-locomotion (quickness) -one pair per segment

Question 28

what are palps used for? what do they resemble?

Answer 28

-sensation -look like antennae whiskers

Question 29

what are the key aspects of the sedentaria clade? what are examples?

Answer 29

-less active (sedentary) -live in marine sediment or soil -can live in tubes -ex: leeches, earthworms, tubeworms

Question 30

why do worms within the sedentaria clade have slower movement?

Answer 30

-no extensions on their segments

Question 31

if worms live in tubes what will they have?

Answer 31

-elaborate gills

Question 32

what may leeches be predators of?

Answer 32

-other invertebrates

Question 33

how do earthworms get their nutrients?

Answer 33

-extracted from the soil

Question 34

what are key aspects of the brachiopoda phylum?

Answer 34

-attached to the seafloor -have a lophophore -no trochophore larval stage -typically lamp shells

Question 35

what does it mean for brachiopods to be considered 'lamp shells'?

Answer 35

-2 muscles (1 for opening, 1 for closing) -dorsal half and a ventral half -also have bilateral symmetry

Question 36

what are the 2 main clades within the brachipods?

Answer 36

-inarticulata -articulata

Question 37

what are the key aspects of the inarticulata clade? what is an example of an organism?

Answer 37

-small or no hinge (not as lamp shell like) -complete gut (mouth, intestinal tract, and anus) -ex: lingula

Question 38

what are the key aspects of the articulata clade?

Answer 38

-large hinge (strong/robust) -incomplete gut (no exit for waste, enters + exits through mouth) -intestine protrudes out the back of the shell

Question 39

what are the key aspects of the platyhelminthes phylum?

Answer 39

-flatworms -rudimentary cephalization (undeveloped) -live in marine/freshwater or terrestrial habitats -gas exchange through the skin -can be free living or parasitic

Question 40

where is there evolutionary loss in platyhelminthes?

Answer 40

-incomplete gut (acoelomate) -only a gastrovascular cavity

Question 41

what does a platyhelminthes flat body help them with? what does it limit?

Answer 41

-disguising -limits room for compartmentalization

Question 42

what does it mean to be parasitic?

Answer 42

-another organism is needed to carry out its lifestyle

Question 43

what is the clade within the platyhelminthes?

Answer 43

-neodermata

Question 44

what are the 2 classes within the neodermata clade?

Answer 44

-parasitic trematodes (flukes) -cestodes

Question 45

what are the key features of the parasitic trematodes? what is an example?

Answer 45

-parasitic -ex: schistosoma parasitic worm (swimmers itch)

Question 46

what are the key features of the cestodes?

Answer 46

-have loss of a gastrovascular cavity over evolution -can reach 20m in length -ex: tapeworms (live inside an organism's intestines)

Question 47

what is an exoskeleton? what is its purpose?

Answer 47

-tough cuticle or shell -protects the organism from environmental conditions

Question 48

what is typically involved when an organism has a exoskelton?

Answer 48

-moulting/periodic shedding followed by rapid growth

Question 49

what is stepwise growth? when does it take place?

Answer 49

-when the exoskeleton sheds, organism grows rapidly, and a new exoskeleton forms (repeats) -when the organism cannot grow continuously and is limited by the size of its exoskeleton

Question 50

when does the process of stepwise growth stop?

Answer 50

-once an organism has reached its full size

Question 51

where did stepwise growth/evolution of an exoskeleton begin?

Answer 51

-ecdysozoa clade -nematoda + arthropods

Question 52

what are the key aspects of the nematoda phylum?

Answer 52

-most common animal on earth -small or microscopic -free living or parasitic lifestyles -pseudocoelomate -body is covered with a cuticle -flexible bodies

Question 53

what type of hosts can a nemotode have?

Answer 53

-plant or animal hosts

Question 54

what is an example of a nematode?

Answer 54

-roundworms