BIOL 111 Lecture Notes - Lecture 18: Shoulder Girdle, Trachea, Exhalation
5 Jul 2018
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BIOLOGY LECTURE 18
Amphibians – Transition from life of Fish to Land
Coelacanth = a living fossil
-Thought to be extinct
-1938: found on South African Trawler
-1998: 2nd species found in Indonesian fish market
-Steal the coelacanth away from the Frenchman, army planes would come to
taunt them to take it from South Africa
-Single skeletal bony element extending from the girdle of the fish into the fin, the
origin of modern fins
Lungfish
-Lobed fins that have bones going in “walk” tetrapod motion
-6 species (Africa, SA, Aust)
-Breathe through gills and primitive lungs
-Estivate in mud during droughts (entuned in mucus to wait until the rain)
TETRAPODS: 4 LIMBS
Why move onto land?
-Droughts (400 MYA)
-Shallow inland seas, swamps, ponds
-Low dissolved 02
-Increased competition in water (if you made it out you would be ahead you kin)
-Crowding in smll pools
-New food resources (e.g. arthropods, plants)
-No vertebrate predators
Difference between land and water:
-Availability of water/moisture
-Density of medium
-Amount of Oxygen
-Stability of Temperature
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Document Summary
Amphibians transition from life of fish to land. 1998: 2nd species found in indonesian fish market. Steal the coelacanth away from the frenchman, army planes would come to taunt them to take it from south africa. Single skeletal bony element extending from the girdle of the fish into the fin, the origin of modern fins. Lobed fins that have bones going in walk tetrapod motion. Estivate in mud during droughts (entuned in mucus to wait until the rain) Increased competition in water (if you made it out you would be ahead you kin) Amount of uv radiation (no shelter of water, dna damage) Air has a higher concentration of oxygen than water. Gases diffuse faster in air than water. We choke because we only have one connection for our lungs and our gut, food and air; it gets divided into our trachea and esophagus, legacy of the fact that we evolved from fish of the same structure.
