Lecture Ten-Eleven: Transition to Land Flashcards
What major changes helped facilitate the transition to land?
- Decreased temp
- Terrestrial arthropods (food)
- Increased coastlines
- Increased shallow water
Why is shallow water important to moving to land?
The temperature is still relatively high.
Higher T = less dissolved gas.
Likely that fish had to start gulping air to get adequate oxygen.
Allowed them to see stuff on land.
With mutation of lungs, they can go there.
Deeper water circulates more oxygen.
What gave arthropods an advantage over tetrapods to advance to land?
- Exoskeleton: provides structure to counteract gravity
- Developed lungs earlier
Why is it easier to support an organism with bones instead of rays?
Skeleton is what muscle contracts against. Not much can attach to thin rays. Bone provides mobility since muscle can contract against it.
Did lobe-finned fishes only occupy shallow water?
No.
What is the advantage of mutations that allows them to persist?
Better able to reproduce.
Will a mutation in one organism lead to large evolutionary changes?
No. Multiple individuals in a population would need to have the mutation.
What is a significant morphological transition as vertebrates moved to land?
The “detachment” of the head from the body (development of cervical vertebrae/neck).
What change occurs in body/limb movement as the amniote body type arises
Limbs can move independently.
Prior, the bodies still moved in a fish-like action with legs following (\/\/).
What develops into lungs?
Swim bladder
What is one of the biggest challenges when moving from water to land?
The environment no longer supports the body. There is no buoyancy to offset gravity.
Why did bones become thicker as vertebrates transitioned to land?
- Combat gravity
- Allows for increased musculature (also helps support body)
Aquatic vertebrates need suction to combat the forces of water when hunting. Does this work on land?
No, the organisms must change how they feed.
As organisms changed how they fed, what else does had to change?
Musculature around the head and shape of the head.
More of what is needed to support increased bone and muscle mass?
Nutrients and protein.
What advantage offsets the cost of high energy requirements for an amniotic egg?
No larval stage needed.
Which animals transitioned away from the water’s edge and more inland?
Amniotes (eggs can be laid outside of water due to protective covering).
Were there organisms prior to amniotes that did not have larval stages?
Yes! (Ex. sea horses, sharks)
Though the majority had larval stages.
Bone fusions take place as tetrapods develop. Why?
Prevents excess movement that would be caused by gravity.
What happens to the metabolic rate as vertebrates transition to land? Why?
Increases.
More energy is needed to build more of the body (thicker bones, more muscle).
What is there a lot more of on land than in the water?
Oxygen.
Why are terrestrial respiratory systems less efficient than aquatic ones?
They don’t have to be – there’s way more air. Air is easier to move than water (less dense).
What becomes a threat in air?
Desiccation.
Where the first amphibians nocturnal or diurnal? Why?
Nocturnal to avoid drying out.
