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Ecology and diversity > Lecture 11 > Flashcards

Lecture 11 Flashcards

1
Q

What is the third embryonic germ layer that arose after the origin of diploblastic animals?

A

The mesoderm (triploblastic)

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2
Q

What are the two clades of triploblastic animals called?

A

Protostomes and deuterostomes

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3
Q

Which of the two clades of triploblastic animals has more numbers of species and individuals?

A

Protostomes

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4
Q

When is the trait of the formation of the blastopore not universally shared?

A

No blastopore forms during early development of insects

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5
Q

What are the characteristics of protostomes?

A

Bilateral symmetry
Anterior brain that surrounds the entrance to the digestive tract
Ventral nervous system consisting of paired or fused longitudinal nerves

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6
Q

What type of coelom is found in protostomes?

A

Acoelomate- flatworms

Pusedocoelomate and coelomate

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7
Q

In what two clades has the coelom been secondarily modified?

A
  • Arthropods

- Mollusks

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8
Q

How has the coelom been secondarily modified in arthropods?

A

Lost their ancestral coelom, internal cavity has become a hemoceol (blood chamber) where open circulatory fluid bathes internal organs

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9
Q

How has the coelom been secondarily modified in mollusks?

A

Open circulatory system

Have some hemocoel but have retained enclosed coelom around major organs

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10
Q

What are the two major clades of protostomes?

A

Lophotrochozoans

Ecdysozoans

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11
Q

What type of skeleton do lophotrochozoans have?

A

Internal skeletons

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12
Q

What type of larvae do many lophotrochozoans have?

A

Trochophore- free living larvae

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13
Q

How do many lophotochozoans move?

A

Cilia

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14
Q

What do several, distantly related groups of lophotrochozoans have?

A

A lophopore

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15
Q

What is a lophopore?

A

A circular or U shaped ridge around the mouth that bears one or two rows of ciliated, hollow tentacles

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16
Q

What is the purpose of a lophopore?

A

Food collection and gas exchange

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17
Q

How has the lophopore evolved?

A

Independently, at least twice, or else it was ancestral and has been lost

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18
Q

What is a characteristic of most individuals with a lophopore?

A

Sessile as adults

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19
Q

What do some lophotrochozoans, including flatworms, ribbon worms, annelids and mollusks, exhibit?

A

A form of radial cleavage known as spiral cleavage- these are a nonmonophyletic group called spiralians

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20
Q

What are members of several groups with radial cleavage like?

A

Worm-like

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21
Q

What is the purpose of a worm-like body?

A

To be able to burrow efficiently in muddy and sandy marine sediment or soil
Except mollusks

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22
Q

What do ecdysozoans have?

A

An exoskeleton

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23
Q

What is the external skeleton of ecdysozoans?

A

Non-living covering secreted by underlying epidermis

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24
Q

What does an exoskeleton provide?

A

Protection and support

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25
Q

How do ecdysozoans grow?

A

By shedding or moulting the exokeleton and replacing it with a new one

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26
Q

What recent evidence showed that molting evolved 500 million years ago?

A

Discovery of cambrian period soft-bodied arthropod

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27
Q

What evidence suggests that ecdysozoans have a common ancestor?

A

Molecular and genetic evidence, including a set of shared hox genes

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28
Q

What happens when an ecdysozoan molts?

A

The new exoskeleton has not yet hardened, the animal is vulnerable- slow moving and soft

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29
Q

What name is given to the exoskeleton of wormlike ecdysozoans that are thin and flexible?

A

Cuticle

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30
Q

What does a cuticle allow?

A

Some protection, little body support, gas, mineral and water exchange

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31
Q

What does a cuticle restrict?

A

Animals to a moist habitat

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32
Q

Where do most animals with a cuticle live?

A

Marine sediment

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33
Q

How do marine sediment worm-like cuticle covered ecdysozoans capture larger prey?

A

Using a toothed pharynx

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34
Q

What is a pharynx?

A

A muscular organ at the anterior end of the digestive tract

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35
Q

What type of eaters are many wormlike ecdysozoans?

A

Predators- eating protists and small animals

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36
Q

How is the exoskeleton of other ecdysozoans thickened?

A

Layers of protein and polysaccharide chitin

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37
Q

What does chitin do?

A

Impedes passage of oxygen and nutrients into the animal

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38
Q

How do animals with hard exoskeletons move rapidly?

A

Apendages- extensions of the body that can be manipulated by mucles

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39
Q

What did evolution of apendages during late precambrian period lead to?

A

Arthropod clade

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40
Q

What triploblastic animal was difficult to classify as protostome or deuterstome and why?

A

Arrow worms because they retained features that are ancestral to diploblastic animals

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41
Q

What is the body plan of arrow worms?

A

Coelom divided into three compartments: head, trunk, tail

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42
Q

Where are most arrow worms found?

A

Swimming in the open sea, some on sea floor

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43
Q

How do arrow worms exchange gas and waste?

A

Diffusion through body surface (due to size between 3mm and 12cm)

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44
Q

What type of circulatory system do arrow worms have?

A

None- waste/nutrients are moved by coelomic fluid propelled by cilia lining the coelom

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45
Q

What type of development do arrow worms have?

A

Direct development

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46
Q

How are arrow worm eggs fertilized?

A

Internally following elaborate courtship between two hermaphroditic individuals

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47
Q

How are arrow worms stabalised in water?

A

By two pairs of lateral fins and a tail

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48
Q

What do arrow worms eat?

A

They are predators of planktonic organisms in the open ocean

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49
Q

How do arrow worms capture prey?

A

They are motionless, movement signals approach of prey, they dart forward and grasp prey with stiff spines adjacent to mouth

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50
Q

How many species of ectoprocts are there?

A

4500

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51
Q

What do ectoprocts live in?

A

colonies in a house made of material secreted by the external body wall

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52
Q

Where do all ectoprocts live?

A

Marine- a few in fresh or brackish water

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53
Q

What is the structure of an ectoproct colony?

A

Small individuals connected by strands of tissue along which nutrients can be moved.

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54
Q

How are ectoproct colonies founded?

A

Asexual reproduction of founding member- 2 million individuals

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55
Q

Where can ectoprocts be found?

A

Rocks in coastal regions in many parts of the world

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56
Q

How do individual ectoprocts increase their contact with prey?

A

By oscillating and rotating their lophophore which can also be retracted

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57
Q

How are eggs fertilized in ectoprocts?

A

Internally, developing embryos are brooded before exit as larvae

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58
Q

What diverse group is found below ectoprocts?

A

Flatworms, rotifers and ribbon worms

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59
Q

What type of coelom do flatworms, rotifers and ribbon worms have?

A

Flatworms- acoelomate
Rotifers- Psuedocoelomate
Ribbon worms- coelomate

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60
Q

How do flatworms keep each cell near their body surface for gas exchange?

A

Dorsoventrally flattened body form

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61
Q

What type of gut does a flatworm have:

A

A mouth opening into a blind sac

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62
Q

What is the structure of a flatworms blind sac?

A

Highly branched

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63
Q

What are some free-living flat worms

A

Cephalized- head bears chemoreceptor organs, two eyes and a brain

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64
Q

How do free-living flatworms move?

A

Glide over surfaces powered by broad bands of cilia

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65
Q

What type of feeding do flatworms have?

A

Most are internal parasites
Other feed externally on living or dead animal tissues
Some are free-living

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66
Q

What are the two groups of most species of living flatworm?

A

Tapeworm and flukes- internal parasites particularly of vertebrates

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67
Q

What disease do some tapeworms and flukes cause in humans?

A

Schistosomiasis

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68
Q

What group of flatworms are external parasites of fishes and other aquatic vertebrates?

A

Monogeneans

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69
Q

What group includes most free-living species of flatworm?

A

Turbellarians

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70
Q

How big are rotifers?

A

50-500 micrometers long

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71
Q

What type of gut do rotifers have?

A

A complete gut as well as specialized internal organs

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72
Q

What type of body cavity do rotifers have?

A

A psuedooel

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73
Q

What is the function of the psuedocoel in rotifers?

A

Hydrostatic skeleton

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74
Q

How do rotifers move?

A

Rapdily beating cilia

75
Q

What is the most distinctive organ of rotifers?

A

Ciliated corona (surmounts head)

76
Q

Coordinated beating of cilia sweep particles of organic matter down through the mouth into what complicated structure?

A

The mastax- which grinds food

77
Q

What species of rotifers has only females?

A

bdelloid rotifers

78
Q

Where do most rotifers live?

A

Freshwater

79
Q

Where do some other rotifers live?

A

Surfaces of mosses or lichens in a desiccated, inactive state until it trains

80
Q

What are ribbon worms also called?

A

Nemerteans

81
Q

What type of excretory system do ribbon worms have?

A

Simple nervous and excretory systems

Complete digestive tract

82
Q

How do ribbon worms move?

A

Small by beating cilia

Large by using waves of muscle contraction to move over or burrow into sediment

83
Q

What is the fluid filled cavity of ribbon worms?

A

Rhynchocoel

84
Q

What lies within the fluid filled rhynchocoel?

A

Hollow, muscular proboscis (feeding organ)

85
Q

How does the proboscis work?

A

Contraction of muscles around rhynchocoel cause proboscis to exit explosively through anterior pore

86
Q

What might line the proboscis?

A

Sharp stylets that pierce prey and discharge paralysis causing toxins

87
Q

Where do ribbon worms live?

A

Largely marine, some live in freshwater or on land

88
Q

What other groups of animals use a lophophore to feed?

A

Brachiopods and phoronids

89
Q

How did the lophophore evolve?

A

Independently, or was lost in other groups

90
Q

When were brachiopods most abundant?

A

Paleozoic and mesozoic eras

91
Q

How big are the 20 known species of phoronids?

A

5-25cm

92
Q

What are characteristics of phoronids?

A

Sessile worms living in muddy or sandy sediments or attached to rock substrate

93
Q

Where are phoronids found?

A

Marine waters, from intertidal zone to about 400 m deep

94
Q

What do phoronids secrete?

A

Tubes of chitin in which they live

95
Q

How do phoronids capture food?

A

Cilia drive water on top of the lophophore tentacles, water moves through, particles are caught and transported to mouth by ciliary action

96
Q

How do phoronids reproduce?

A

Eggs are released into water to be fertilized, but some eggs are retained in certain species to be brooded until hatching

97
Q

What are brachiopods?

A

Solitary marine animals with a rigid shell dividing them into two parts connected by a ligament

98
Q

What do brachiopods superficially resemble?

A

Bivalve mollusks- shells evolved independently

99
Q

How are brachipods shells different to mollusk shells?

A

Brachiopod shells are dorsal and ventral- bivalves have lateral shells.

100
Q

Where are brachiopods lophophores located?

A

Within their shells

101
Q

How big are brachiopods?

A

4-6cm long, up to 9

102
Q

How do brachiopods live?

A

Attached by short, flexible stalk to solid substratum or embedded in soft sediment

103
Q

How are gasses exchanged in brachiopods?

A

Across body surfaces

104
Q

How are annelids and mollusks related?

A

They are sister groups

105
Q

How are annelids different to other worm groups?

A

They are clearly segmented

106
Q

What is the name given to the unique body plan of mollusks?

A

Tripartite body plan

107
Q

What were the earliest segmented worms?

A

Preserved in fossils from the late cambrian, they were burrowing marine worms

108
Q

In most annelids, how is the coelom arranged?

A

Each coelom in a segment is isolated from the other segments

109
Q

What is the name given to the nerve centre that controls the coelom of each segment of an annelid?

A

Ganglion

110
Q

How are ganglions function coordinated?

A

Nerve cords connect ganglion

111
Q

What is the surface of most annelids?

A

A thin, permeable body wall for gas exchange- thus most are restricted to moist environments

112
Q

Where do annelids live?

A

Marine, freshwater, moist terrestrial environments

113
Q

What are two major groups of annelids?

A

Polychaetes

Clitellates

114
Q

Where do most polychaetes live?

A

Marine, burrowing in soft sediments

115
Q

How many eyes do polychaetes have?

A

One or more pairs

116
Q

How many tentacles do polycheates have?

A

One or more pairs

117
Q

Where are polychaetes tentacles and what do they do?

A

At the anterior end

Filter prey from surrounding water

118
Q

In polychaetes, how are segments arranged?

A

Body wall of most segments extends laterally in a series of thin outgrowths called parapodia

119
Q

What are parapodia in polychaetes?

A

Paired bristle appendages used for locomotion, sensation or respiration

120
Q

What protrudes from parapodia?

A

Setae- stiff bristles

121
Q

What do setae do on polychaetes parapodia?

A

Form temporary attachments to the substratum

122
Q

What is the name of the clade of polycheates that lost their digestive tract?

A

pogonophorans

123
Q

What are pogonophorans?

A

Burrowing animals with a crown of tentacles through which gas exchange occurs

124
Q

What do pogonophorans live in?

A

A tube of chitin and other substances which they secreted

125
Q

What does the pogonophoran coelom consist of?

A

An anterior compartment into which tentacles can be withdrawn and a long, subdivided cavity the length of most of the body

126
Q

What end of the pogonophoran body is segmented?

A

The posterior end

127
Q

What do pogonophorans eat?

A

Dissolved organic matter in the sediment in which they live or surrounding water

128
Q

How is uptake of nutrients by pogonophorans facilitated by? In which organ does this occur?

A

Endosymbiotic bacteria

Trophosome

129
Q

Where do most clitellates live?

A

Freshwater or terrestial environments

130
Q

What are the two major groups of clitellates?

A

Leeches and oligochaetes

131
Q

What are some characteristics of oligochaetes?

A

No parapodia, no eyes, no anterior tentacles, few setae.

132
Q

What is a familiar oligochaete?

A

Earth worms

133
Q

What is a common feature of all oligochaetes?

A

They are hermaphroditic (each individual is born male and female)

134
Q

How is egg and sperm exchanged between oligochaetes?

A

Simultaneously between two copulating individuals

135
Q

What do oligochaetes do with their eggs?

A

Lay them in a cocoon outside of the adults body

136
Q

What happens to the eggs laid in a cocoon by oligochaetes?

A

The cocoon is shed when development is complete and miniature, independent worms emerge

137
Q

What are some features of leeches?

A

They lack parapodia and tentacles, undivided coelom, filled with undifferentiated tissue

138
Q

What are groups of segments at each end of a leeches body modified into?

A

Suckers, used for temporary anchoring to aid movement

139
Q

How does a leech move along the substratum?

A

The posterior sucker attaches, the leech extends its body by contracting circular muscles, leech shortens by contracting longitudinal muscles, etc.

140
Q

Where do leeches live?

A

Freshwater or terrestrial habitats

141
Q

How do leeches suck blood?

A

Makes an incision in the host.

Secretes an anticoagulant to keep blood flowing

142
Q

What is the name of the medicinal leech?

A

Hirudo medicinalis

143
Q

What is Hirudo medicinalis used for?

A

Reduce fluid pressure and prevent blood clotting in damaged tissues, to eliminate pools of coagulated blood and to prevent scaring

144
Q

What are the anticoagulants of other leeches being studied for possible medical uses for?

A

contain anesthetics and blood vessel dilators

145
Q

What were the probable features of the ancestors of modern mollusks?

A

Unsegmented, wormlike animals

146
Q

What have mollusks undergone?

A

A dramatic evolutionary radiation

147
Q

The evolution of what feature set the stage for the dramatic animal evolutionary evolution of mollusks?

A

Tripartite (three parts) body organization

148
Q

What are the three major components of the mollusk body plan?

A

A foot, visceral mass, mantle

149
Q

What is the foot of a mollusk?

A

A large, muscular structure

150
Q

What was the mollusk foot originally used for?

A

Locomotion and support of internal organs

151
Q

What happened to the mollusk foot in squids and octopuses?

A

It was modified to form arms and tentacles

152
Q

What is the foot used for in clams?

A

A burrowing organ

153
Q

What is the visceral mass of mollusks?

A

Where the heart, digestive tract, excretory and reproductive organs are concentrated

154
Q

What is the mantle of mollusks?

A

A fold of tissue that covers the organs of the visceral mass, secretes a hard calcareous shell typical of many mollusks

155
Q

What happens with the mantle in most mollusks?

A

It extends beyond the visceral mass to form a mantle cavity

156
Q

What is within the mantle cavity in mollusks?

A

vascularized gills for gas exchange

157
Q

How is a current of water generated to move over mollusks gills?

A

Cilia beat

158
Q

How do mollusks feed?

A

Gills can be used as a filter feeder,

Others used a rasping structure called a radula to scrape algae from rocks

159
Q

Where has the radula been modified and what into?

A

Marine cone snails

Into a drill or poison dart

160
Q

What circulatory system do mollusks have?

A

Not a closed system

Fluid empties into large hemocoel

161
Q

What are 5 major groups of mollusks?

A 
Monoplacophorans
Chitons
Bivalves
Gastropods
Cephalopods
162
Q

How are monoplacophorans different to all other living mollusks?

A

Gas exchange organs, muscles and excretory pores are repeated over the length of the body

163
Q

What characterizes chitons?

A

Multiple gills and shell plates, bilateral symmetry, simple internal organs

164
Q

What do most marine chitons eat?

A

They are marine herbivores

Scrape algae from rocks with radulae

165
Q

How do chitons move?

A

Slowly by rippling waves of muscular contraction in the foot

166
Q

Where does fertilization of chitons take place?

A

In the water

Sometimes internally and then brooded

167
Q

What are some familiar examples of bivalves?

A

Clams, oysters, scallops, mussels

168
Q

Where are bivalves found?

A

Marine and freshwater

169
Q

What is the body plan of bivalves?

A

Small heads, hinged two-part shells

170
Q

What do most bivalves use their foot for?

A

To burrow into mud and sand

171
Q

How do bivalves feed?

A

By taking water in through an incurrent siphon and filtering out food using their gills

172
Q

How does water and gametes exit bivalves?

A

Through their excurrent siphon

173
Q

Where does fertilization of bivalves take place?

A

In open water

174
Q

Give some examples of gastropods.

A

Snails, whelks, limpets, slugs, naudibranchs, abalones

175
Q

How do gastopods move?

A

Gliding on their muscular foot,

Swimming using foot (sea butterflies, heteropods)

176
Q

What are two features of naudibranchs?

A

Lost their protective shell

Aposematic or camouflaged coloring

177
Q

How many parts make up the shell of shelled gastropods?

A

one

178
Q

In terrestrial species of mollusks (gastropods only) what is the mantle tissue modified into?

A

Highly vascularized lung

179
Q

Name some cephalopods.

A

Squids, octopuses, nautiluses

180
Q

How is the excurrent siphon modified in cephalopods?

A

To allow the animal to control water content in mantle cavity- move by jet propulsion

181
Q

What did jet propulsion of cephalopods allow

A

Them to become major predators

182
Q

How do cephalopods capture and subdue prey/

A

With their tentacles

183
Q

What cephalopods still have chambered shells to control their buoyancy?

A

Nautiloids

Ecology and diversity (17 decks)

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