Comment on the features that enabled the amphibians to migrate to land.?

Answer 1

Be back.

To survive in its most primitive form. One must be able to:
Breath.
Drink.
Eat.
Move.

All amphibians can do this task to some extent, and they have (or have developed)the equipment or organs to do it.

Once they have the capacity, they can stay on land longer and longer, and evolve in to land based creature over generations, ultimately loosing their aquarian characteristics and abilities.

Answer 2

features that enabled amphi. to migrate on land were
1 a rigid backbone that supported their body weight
2limbs that could raise body above ground
3air breathing breathing mechanism
4moist skin to prevent dessication
5mechanisms to procure food

Answer 3

Comment on them?
List them?
Define and describe them?

Well.... sure... I'll help you with this one...

#1. Limbs. ~ While underwater, beings can manage to get by with just a figure-of-eight motion as can be achieved with simple flippers... that just doesn't work out of water when motion has to be through contact with the substratum rather than the surrounding medium. Hinged limbs were a big help...

#2. Clawed toes. ~ Along with the limbs themselves, in order to move over the substratum it made sense that they need actually gain purchase on it... i.e. grip. Once claws developed, this became possible, and early tetropods were actually able to pull themselves along rather than just flail like idiots...

#3. Spinal / Skeletal Strengthening. ~ Needless to say air isn't as strong a supportive medium as water. Thats why to this day the largest creatures will be found in the water, since a terrestrial environment wouldn't allow for support of their weight.
The key strengthening adaptations would have to be in the spine and the ribcage, naturally. The spine is the support for the rest of the skeleton, especially the limbs... and through it the entire body would be supported. The ribcage is responsible for protecting and supporting the main portion of the body's internal organs... and in the case of early amphibians was the difference between survival on land and dying due to one's guts spilling out onto the sand.

#4. Waterproof skin. ~ Regardless of our being land-creatures, we still need a lot of water inside us to survive... and that requires that there isn't free flow of water between the outside and the inside, since it will always move to the area of lowest concentration... i.e. the air. Waterproof skin was a bit of an ongoing development for early amphibians. Many amphibians even these days can't stay out of the water for too long or they'll dry out... Some measure of waterproofing had to be achieved before transition to the land could even begin though.

#5. Sensory Readjustment. ~ Eyes and ears designed to see and hear respectively underwater simply aren't going to work the same way on land. Water and air have entirely different densities, which means different refractive indecies. This requires recalibration of the senses to work in a far less dense medium... As it happens, this isn't as vital as some other adaptations, but any creatures with adapted senses for land navigation would be at a huge advantage over their blinded / deafened counterparts.

#6. Lungs. ~ You knew this was going to come up sooner or later, didn't you? ... Lungs were probably one of the earlier adaptations of tetrapods in shallow water environments as they drew closer to terrestrial adaptation... allowing them at the very least to 'survive' out of the water for short periods, whether they could move and actually 'live' there or not. When its the only place you can go to escape predation, its an oppurtunity not to be missed. The actual removal of the gills would have happened a lot later on however... once full terrestrial adaptation had taken place and they had become superfluous.


Have I missed anything?
Its entirely possible that I might have...
But then I can't remember right now, so it won't have to matter.

Oh... and just in case anyone isn't paying attention... this is an important point: Evolution doesn't predict what its adapting to. Mutations happen randomly, and IF they happen to be beneficial for whatever reason, then they stick. The changes listed could only have happened gradually in partial stages... bit by bit allowing early tetropods to move -toward- the land... gradually enabling them to function better in shallower waters and eventually for brief to longer stretches out of the aqueous medium.

So... thats that then.

Answer 4

limbs, lungs to breathe

Answer 5

They were a good thing.

Answer 6

stubs of feet.