8. Beginning of Tetrapods and Amphibia Flashcards
Thermoregulation
Most fish are coldbloded, which means that thay have the same temperature as their evironment.
Some fishes produce warmth through swiming, which make them more efficient.
Osmoregulation
All fish except for hagfish have a problem with the saltiness in the ocean.
Freshwater - Their body is salty, so the salt attracts the water into the fish until the fish actually would explode. They deal with this problem through urinating. They are constantly piing.
Saltwater - fish are constantly drinking water, what haha. Because they are losing water, because the saltwater is more salt then their body.
The different fish senses?
Vision - Most daylife fishes have as good colorvision as humans.
Chemoreception - taste and smell
Lateral line system - They sense vibrations in the water like we can feel the vind on the hair of our body. Furtermore they can sense the motion of nearby fish and pray.
Actinopterygii
Ray-Finned fishes
There fins are webs of skin by bony or horny spines (rays).
imagien the normal fish fin, thats how a ray fin looks like.
Subclass
Sarcopterygii
Underclass of Osteichtyes
The so called lobe-finned fishes
The word Sarcopterygii means “fleshy fin”, so there fins are different from the ray-finned fishes.
The fins are stronger, because of the bony different bony structure, which make them useful for moving in shallow water and sediments, but not to walk on land.
In this group, we have the tetrapoda, there include humans, aphibians, birds, reptiles and mamals.
What is cosmoid scales?
Scales covered with cosmine, which is a combination of tissues and structure.
It makes a pore-channel system, there allows water to pass through the network of horizontal canals.
This make the fish able to sense movement in the water, like we can feel the wind blowing on our arm.
Why do all marine teleost fish seem to be descended from freshwater fish?
Because of past extinction from marine water, which cilled all the fish in the ocean.
What challenges the transition to land from water?
Oxygen content is much higher in air.
Fluid density - air provides less support against gravity compared to in the water. Fx the body of the wale can´t support itself. Its body collapse.
Temperature regulation - water is better at keeping the same temperature.
Vision and hearing - In water a wale can sing and be heard 100 of km away.
Respiration in details
One thing is to have lung, but another thing is to breath out of water. Fx the lungfish needs the water around it to breath, because it supports its lungs.
Analogy with first aid. You place people on the side, so its able to breath. Theirfore becomes leegs really important, beacuse it lift the fish of the ground.
And ribs becomes important.
Double circulation system.
Gravity specifics
Here the water can´t support the body, so the fishes needed a strong skeleton.
This skeleton had different stress points, than the previous one.
Temperature regulation specifics
For the earlist species there came upon land, we can only suppose that they had the same behaviour as amphibiants.
Its related to water loss, så shaded an wet habitats are the best.
To prevent water loss, they had bony scales or plates
Muscus secretion.
Tolerance of salt concentration in the body tissues.
An permeable skin allowed water to be absorbed from humid soil.
