Exam #2

Question 1

Explain how the radula of the Mollusc Class Gastropoda has been modified from the ancestral mollusc.

Answer 1

Radula is used in same manner as ancestor.

Strap like toothed structure, used to tear & grind solid food

Question 2

Explain how the radula of the ancestral Mollusc was used.

Answer 2

Strap like toothed structure, used to tear & grind food

Question 3

Explain how the radula of the Mollusc Class Cephalopoda has been modified from the ancestral mollusc.

Answer 3

Turned into a beak or ancestral radula still used to tear & grind found behind beak

Question 4

Explain how the radula of the Mollusc Class Bivalvia has been modified from the ancestral mollusc.

Answer 4

Lacks radula, b/c they feed by filtration

Question 5

Explain how the shell of the Mollusc Class Gastropoda has been modified from the ancestral mollusc.

Answer 5

Shell coiled

Used for protection & not as long in coiled form as it would be straight

Question 6

Explain how the shell of the Mollusc Class Bivalvia has been modified from the ancestral mollusc.

Answer 6

Hinged shell protects against predation

Question 7

Explain how the shell of the Mollusc Class Cephalopoda has been modified from the ancestral mollusc.

Answer 7

Shell internalized, lost or coiled

Question 8

Explain how the shell of the ancestral Mollusc was used.

Answer 8

Thick calcareous cap-shaped shell, used to cover body and protect against predation and environmental stresses

Question 9

Explain how the foot of the ancestral Mollusc was used.

Answer 9

Large flat muscular foot, used to creep slowly in benthic aquatic habitats

Question 10

Explain how the foot of the Mollusc Class Gastropoda has been modified from the ancestral mollusc.

Answer 10

Foot covered in slime consisting of its urine, cilia used to move

Question 11

Explain how the foot of the Mollusc Class Cephalopoda has been modified from the ancestral mollusc.

Answer 11

Foot modified into tentacles for grasping & siphon

Question 12

Explain how the foot of the Mollusc Class Bivalvia has been modified from the ancestral mollusc.

Answer 12

Foot used to burrow into soil by pushing it into the soil then fattening the end and moving it back and forth, this is repeated

Question 13

Explain the parasite/host biology of freshwater unionid mussels (Mollusca)/fish

Explain the parasite’s lifecycle
Explain how it colonizes the host & where on it it lives.

Answer 13

The freshwater unionid mussels use a lure to attract fish into biting it. Being bitten, it releases the mussel’s Glochidia larvae which attach to the gills of the fish. The glochidia feed by absorbing nutrients from the blood supply. After maturing, they release their grip on the fish & float to the bottom to start their sessile adult life.

Question 14

freshwater unionid mussels (Mollusca)/fish

Describe 2 key adaptations (behavior, physiology &/or morphology) used by the parasite to colonize and/or survive in its host.

Answer 14

1 evolution of the lure that is used to find the host

Question 15

Explain the parasite/host biology of thorn-headed worms (Acanthocephala) / duck

Explain the parasite’s lifecycle
Explain how it colonizes the host & where on it it lives.

Answer 15

Free swimming larvae eaten by Gammarus (invertebrate) where they attach to the inside of the definitive host. While infected the invertebrate changes it behavior & color. The uninfected invertebrate will hide in the darkness from predators at the bottom of the water source where they live. An infected one will change color to become more visible and behave as if it were mating season. They come out of hiding not worried about predation and attach themselves to foliage near the surface making them easy prey for ducks. If there is another thorn-headed worm of opposite gender they will attach to the gut with their spiny proboscis for the rest of their lifecycle, mate and their fertilized eggs defecated out.

Question 16

Thorn-headed worm (Acanthocephala) / duck

Describe 2 key adaptations (behavior, physiology &/or morphology) used by the parasite to colonize and/or survive in its host.

Answer 16

#1 spiny proboscis used to attach to the definitive host
#2 the effect it has on the behavior of the invertebrate intermediate host

Question 17

A difference between annelid subclasses Oligochaeta & Hirudinea is:

Answer 17

Oligochaeta have few chaeta (bristles) while Hirudinea has many

Question 18

Feeding Nemertea evert their proboscis with a series of actions that occur in what sequence?

Answer 18

Contract sphincter muscles, contract circular muscles, pressurize rhynchocoel, relax sphincter muscles

Question 19

The metanephridia in mollusca does what?

Answer 19

draws in coelom fluids w/ciliates cells in funnel region, selectively re-absorbs useful material from urine in tubule region, expels urine into mantle cavity, is more efficient at filtering wastes from large amounts of fluid than protonephridia

Question 20

gills are found in what invertebrates?

Answer 20

Those with circulatory system

Question 21

what is the difference betweeen torsion & the coiled body?

Answer 21

coiling allows for a compact body
torsion only occurs in the class Gastropoda, but the advantage is unclear

Question 22

What features are found in Nemertea but not Nematoda??

Answer 22

closed circulatory system
acoelomate body
create hydrostatic pressure w/circular muscles

Question 23

Where is the metanephridia located in Annelida?

Answer 23

throughout the body due to their coelom being partitioned with septa

Question 24

What feature of Nematoda indicates they are more closely related to Arthropods than Rotifers

Answer 24

a multi-layered cuticle that is molted

Question 25

What feature is found in Acanthocephala and Nematoda?

Answer 25

Pseudocoelom

Question 26

The origin of bilateral symmetry is closely associated with the evolution of:

Answer 26

The central nervous system

Question 27

Which Rotifera are useful adaptations for life in temporary aquatic habitats?

Answer 27

winter eggs
parthenogenesis
cryptobiosis