A change for the better!


Pile of T. saginata taken by Carolyn Temanson


The tapeworm is a master at adapting to its surroundings.  Its flat body is ideal for absorbing maximum amount of nutrients because of it surface area to volume ratio.  A scolex was formed so the adult could say attached to its host, especially when its prime living space is in the intestine. Remember the intestine works at removing waste from the body so a strong attachment point is necessary for staying in the gastrointestinal tract.  The tapeworm also took advantage of the intestine to help it continue its life cycle and reproduce, so it developed the segmented proglottids that would break off and be passed through the feces.  The feces of it definitive host would be released into the external environment and the cow would then eat the grass that was contaminated with the eggs allowing the larvae to have an intermediate host to reside. 


This picture of a full grown adult Taenia saginata shows how long these tapeworms can grow inside a human's intestine.


Now, the relationship between cattle and humans are only recent, because domesticating these animals and farming is a fairly new occurrence when looking at the process of evolutionary adaptation.  It is said that Taenia tapeworm’s origin actually began in Africa with the hominids and Homo genus.  This was even before the modern human beings were even seen in Africa.  It is believed that the carnivorous lifestyles, preying on antelope and other bovids, that these pre-human species had lead to the evolution of Taenia using humans as their definitive host.  Now, with the most recent domestication of animals in farming, in the aspects of evolution, Taenia have gone through the process of adaptive radiation and have modified to different niches and infecting different intermediate hosts.  Examples of this would be the pork tapeworm, T. solium, or  T. pisiformis found in rabbits. 



Now take a closer look at the Life Cycle of Taenia saginata.