BIOL371 MIDTERM TEST EXAM QUESTIONS AND
ANSWERS WITH COMPLETE SOLUTIONS GRADED
A++
Gonochorism
Separate, fixed sexes
Hermaphrodism
Both sexes in one individual
Protoandry
Changing from male to female
Protogyny
Changing from female to male
Planktotrophic larvae
High numbers of eggs and sperm released into the water column
No parental care put in to ensuring the offspring's survival
Offspring have to feed (no nutrient sac in the egg)
Longer developmental period in the pelagic zone meaning they are more vulnerable to
predation
Much smaller when they hatch
Wider dispersal as they are laid into the water column
Lecithotrophic larvae
, Do not have to feed in the pelagic zone as the eggs contain a nutrient yolk sac
Not as many offspring created
More time and energy put into the offspring's survival (yolk sac)
Direct development
All of the developing is done within the egg
Offspring hatch as mini juveniles and not larvae
Localised dispersal, larvae stay close to the parents
What is Thorson's 1950 rule? Why?
That there is typically planktotropic larvae in the tropics and lecithotrophic and direct
development in the temperate zones. This is due to nutrient availability being much
more constant in the tropics and unpredictable in the temperate zones.
Why do fish time their spawning with the new and full moon?
These times experience the strongest tides that sweep the eggs and sperm off the reef
and out to sea, away from the parents very quickly.
Also because of DMV (vertical migration) of animals from the deep sea that like to feed
on plankton and other organisms in the water column. However they do not do this
when there is high levels of light in the water as to avoid being seen by other predators
so at the full moon they don't migrate.
Why do larval fish settle on the new moon?
Low light allows them to avoid being seen by predators on the edge of the reef and
increases the chances for successful settlement.
Semelparity
Spawn once and then die
ANSWERS WITH COMPLETE SOLUTIONS GRADED
A++
Gonochorism
Separate, fixed sexes
Hermaphrodism
Both sexes in one individual
Protoandry
Changing from male to female
Protogyny
Changing from female to male
Planktotrophic larvae
High numbers of eggs and sperm released into the water column
No parental care put in to ensuring the offspring's survival
Offspring have to feed (no nutrient sac in the egg)
Longer developmental period in the pelagic zone meaning they are more vulnerable to
predation
Much smaller when they hatch
Wider dispersal as they are laid into the water column
Lecithotrophic larvae
, Do not have to feed in the pelagic zone as the eggs contain a nutrient yolk sac
Not as many offspring created
More time and energy put into the offspring's survival (yolk sac)
Direct development
All of the developing is done within the egg
Offspring hatch as mini juveniles and not larvae
Localised dispersal, larvae stay close to the parents
What is Thorson's 1950 rule? Why?
That there is typically planktotropic larvae in the tropics and lecithotrophic and direct
development in the temperate zones. This is due to nutrient availability being much
more constant in the tropics and unpredictable in the temperate zones.
Why do fish time their spawning with the new and full moon?
These times experience the strongest tides that sweep the eggs and sperm off the reef
and out to sea, away from the parents very quickly.
Also because of DMV (vertical migration) of animals from the deep sea that like to feed
on plankton and other organisms in the water column. However they do not do this
when there is high levels of light in the water as to avoid being seen by other predators
so at the full moon they don't migrate.
Why do larval fish settle on the new moon?
Low light allows them to avoid being seen by predators on the edge of the reef and
increases the chances for successful settlement.
Semelparity
Spawn once and then die
