Amphibians Flashcards
What set the stage for the invasion of land?
Evolution or lung like sacs in response to the inadequacy of gills in oxygen poor waters
What did the evolution of lung like sacs allow
Allowed them to breathe in air and leave the water temporarily
What was the first lineage to evolve jointed limbs?
Sarcopterygii - lobe finned fish
In what ways do lobe finned fish differ from ray finned?
The fins are attached on a fleshy, lobe like scaly stalk extending from the body
Pectoral and pelvic fins resemble tetrapods limbs
Teeth covered with enamel
How are lungfish specially adapted
Have lungs and gills, can burrow in mud when ponds dry up surviving for months inactive breathing air
Believed to have given rise to the tetrapods
What is the prototetrapod?
A descendant of lungfish
What fossil represents an intermediate between a finned fish and limbed tetrapod?
Devonian fossil found on Ellesmere Island
- pectoral girdle seperate from skull
- fins separated from opercular bones
What is the advantage of separating the pectoral girdle from the skull?
Feeding
- greater mobility of skull, greater feeding
- snout and jaws become elongated
- improved articulation of the jaw and expansion of primary palate
Why did lobe fins evolve into limbs? (Advantages of terrestrial land)
- adaption to temporary and shallow pools
- foraging above water surface (insects, plants)
- juvenile dispersal movements
- escape from predatory fish
- new semi-terrestrial foraging niches available
What happened because of the movement to terrestrial life
- smell, airborne now, olfactory organs had to adapt
- reproduction, can no longer do spray fertilisation
- adapted to breath air through skin and lungs, so circulatory system needed to adapt
- implications for sound conduction because of pectoral girdle divorcing from skull
What skeletal changes occurred due to terrestrialisation?
- undulatory locomotion
- suspension of vertebral column
- regionalisation of vertebral column
- organisation of amphibian vertebrae
- suspension of internal organs
- reorganisation of the skull
How did amphibians deal with water loss through evaporation?
Producing concentrated urine in kidneys
What is the buccal pump?
The method of extracting oxygen from the air
- opens mouth, closes opercula,
- depresses buccal floor, increasing the volume
- air enters, closes its mouth, then depresses the buccal cavity
- air is forced into the lungs
- positive pressure system
- elastic recoil of the lungs forced air out the operculum
What is the problem with fish form vertebrae?
There is no support so sags on land when there is no buoyancy
What did terrestrial animals evolve in their vertebrae?
Zygapophyses
Regions of vertebra that fix against the preceding vertebra to form a stop, stopping it from bending downwards
