Amphibians Flashcards
(30 cards)
what are the two groups of bony fish?
ray finned fish and lobe finned fish
Coelacanth was thought to go extinct but in 1938 was found in a…
South African fish market
How do Lungfish “walk”
they walk on their lobe-fins
How do Lung fish breathe?
They breathe through their gills and primitive lungs
What do lung fish do during droughts?
estivate in mud and wait until the water comes back
Tetrapod is an animal with ___ limbs
four
why move on land?
Devonian droughts - shallow inland seas, swamps and ponds
why move on land?
Increased competition in the water - small pools were becoming crowded
why move on land?
New food resources on land such as arthropods and plants
why move on land?
No vertebrate predators - a way to escape predators
What are the five differences between land and water as relevant to life?
- availability of water/moisture
- density of medium
- amount of oxygen
- stability of temperature
- amount of UV radiation
What are the advantages of terrestrial respiration?
Air has a higher concentration of oxygen
What are the advantages of terrestrial respiration?
Gases diffuse faster in air than water
- insects don’t ventilate
Most gas exchange is through which process?
diffusion
Lung evolution: 2 ventral pockets formed off of the??
esophagus
Problems on Land?
water needed to prevent desiccation
- gas exchange requires a moist surface
- water is often required for fertilization
- water is recovered through condensation (important for animals who live in deserts)
- water is required to keep eggs moist so they don’t dry out
Problems on Land?
air is less dense than water
- requires stronger skeletal support muscles - body is mostly water so you don’t need a lot of force pushing up on you in water
Problems on Land?
Air temperature is more variable
- body temperature will fluctuate more
- need to modify behaviour/physiology
- water has a pretty stable temperature
- temperature change from day to night is very drastic
Problems on Land?
UV Radiation
- physical protection or change in behaviour is necessary
- can lead to mutations
Tetrapod solutions to land problems: Air is less dense than water
tetrapods have stronger limbs, vertebral columns, ribs to help them carry their bodies around on land
What was the tail used for in early tetrapods?
balance (not swimming)
Tetrapod solutions to land problems: O2 to be brought in and distrubited
more efficient circulatory system
what kind of circulatory system do tetrapods have?
3 chambered heart double circuit of blood flow
what’s the circulatory system in fish?
- 2 chambered hear
- blood oxygenated in the gills
- single circuit circulation
- relatively low pressure is required
