Anatomical and Physiological Evolution
Peggy Robb
Bio-101
March 29, 2012
Roberto Jimenez
Anatomical and Physiological Evolution
As populations evolve and the environment changes, genes naturally select features in anatomy and physiology that reinforce the survival of a species. To escape the dangers of extinction a species gene pool will make changes and pass those changes down to the next generation. This is evolution. Sometimes these changes are observable, such as the case of the English moth. Sometimes these changes are only observable after looking back over history, such as the case of the lungfish. This paper will be a study on the anatomical and physiological evolution of the lungfish.
Evolution of Lungfish
Sarcopterygii are fleshy-finned fish that first appeared in the Early Devonian period. The Dipnoi are believed to have evolved from this period. The Dipnoi are unusual in their features and the way in which they have evolved over-time to adapt to their changing environment. These fish are an interesting study because of their body form, large size, detached distribution over Earth’s regions, and strange mode of life.
Lungfish Today
Most lungfish weigh up to 22 pounds and are around four-feet long. African lungfish can grow to be seven-feet long and weigh up to 40 pounds. It is interesting to know that lungfish can breathe with both gills and lungs. The lungfish uses its gills to breathe in lakes and swamps when it is the wet season in its region, and uses lungs to breathe during the dry season. The lungfish is also capable of “walking” on land to find mud or water to survive. When there is no water the lungfish will dig a hole in the mud, secrete a liquid around its body to keep from drying out, and aestivate (be dormant).
The Term Paper on Evolution 10
We act like animals, we eat like animals, and we are animals. The many theories of evolution such as Darwin's theory of evolution prove to us that we choose to believe that we are not animals when we really are. Evolution is the sequencial process of change over periods of time, which shapes and establishes the formation of modern man. In referring to evolution, the word means various changes. ...
The question that arises is how did the lungfish develop its leg like fins, lungs for breathing atmospheric air, and ability to lay dormant for such a long period of time.
Anatomical Evolution
The evolutionary line of the lungfish can be traced back as far as the Late Devonian period. Here the Dipnoi (lungfish) exhibited a smaller front dorsal fin and the second dorsal fin was larger and closer toward the tail. These fins in the Permian period fused together giving the Dipnoi better movement in the water. The tips of these fins developed a heightened sensitivity to warn the fish of predators and possible prey.
Evolution suggests that during the Triassic period the Dipnoi began to evolve to survive in a dryer climate. The Dipnoi genes began to change with each generation to include a change in the pectoral fins. This change made the fins evolve into a more thin rod-like structure the fish could use to maneuver over land. These long fins rotate in a circular motion propelling the Dipnoi forward over land and giving the fish stability.
During the Cretaceous period, another evolutionary change took place with the Dipnoi. The modern fish population began to grow causing the food supply the Dipnoi relied upon to drop. This prompted genes to make changes for the Dipnoi to have a broader menu. The Dipnoi’s upper jaw developed two round teeth near the front and the lower jaw developed crushing teeth. The Dipnoi are now able to eat clams, mollusks, snails, crawfish, and shrimp as well as its usual diet of smaller fish.
Physiological Evolution
During the Triassic period, the Dipnoi was undergoing physiological changes as well as the anatomical changes that was discussed previously. In addition to the development of the pectoral fins, the Dipnoi’s genes began rewriting its physiology to include lungs. This development is where the Dipnoi gained the name lungfish. This special lung derived from the swim bladder of the fish gives the lungfish the ability to breathe atmospheric air for long periods, up to four years in some cases. The lungfish can now survive in the environment it was distributed to.
The Essay on Locomotion In An Animal With An Endoskeleton (Fish)
* Water has a higher relative density (800 times higher than air) and is a viscous medium to move through. * The body of a fish is of a streamlined shape to move quickly in water. * The streamlined shape of a fish: * a) is long ellipse tapering to a point (shaped like a torpedo) in the direction of the flow of water. * b) reduces the drag (a drag is water resistance caused by friction between ...
In Africa and Australia, the climates go through wet seasons and long periods of dry seasons. During the wet season, the lungfish breathes oxygen through its gills as it lives in the water. It is known to come up occasionally to breathe atmospheric air through its mouth, but generally, it stays in the water. During the dry season just before the lakes and rivers have dried up, while other fish are dying, the lungfish uses its lungs and pectoral fins to begin digging a burrow in the bed of the lake.
When it has made its burrow, the lungfish secretes a mucus that encases their body and hardens much like a cocoon. The lungfish can stay in this cocoon environment for up to four years waiting for water to come. When water comes, the lungfish awakens from its dormant state, crawls out of its burrow, and uses its pectoral fins to maneuver itself to water where it uses its gills to breathe once again.
Conclusion
It is clear that the evolutionary process helped the lungfish to survive in its changing environment. Overtime the genetic structure of the Dipnoi changed its anatomy and physiology to survive in and out of water and sustain life in a dry climate. If the Dipnoi had remained a fish in this particular region, it would have become extinct. It is amazing to see the evolutionary development of the lungfish as it underwent the changes necessary for survival.
References
AnimalPlanet. (2008).
Fooled by nature. Retrieved March 28, 2012, from YouTube: http://www.youtube.com/watch?v=tqWciuuKn3c
Lungfish. (2012).
Retrieved March 28, 2012, from Animal Planet: http://animals.howstuffworks.com/fish/lungfish-info.htm
The Essay on Water Quality Vs. Fish Population
INSTRUCTIONS: •On your own and without assistance, complete this Lab 1 Answer Form electronically and submit it via the Assignments Folder by the date listed on your Course Schedule (under Syllabus). •To conduct your laboratory exercises, use the Laboratory Manual that is available in the WebTycho classroom (Reserved Reading or provided by your instructor) or at the eScience Labs Student Portal. ...
Lungfish. (2012).
Retrieved March 28, 2012, from Encyclopedia Britannica: http://www.britannica.com/EBchecked/topic/351582/lungfish/63419/Adaptations-for-breathing#toc63420
Simon, E. J., Reece, J. B., & Dickey, J. L. (2010).
Essential biology with physiology (3rd ed.).
San Francisco, CA: Pearson/Benjamin Cummings.
