Throughout the year, we have discussed the Relationship Between Structure and Function in regards to proteins. Proteins are the epitome of this Biological Theme as they follow either the Lock and Key relationship with their specific substrates. Proteins are the first things that come to mind when the theme "Structure and Function" is ever mentioned, yet Shubin thinks differently. As opposed to any typical AP Bio student, he thinks about teeth. In chapter four, "Teeth Everywhere", Shubin describes how the structure and shape of a tooth can reveal the history of how animals processed their food. Using the Biological Theme of The Relationship Between Structure and Function, answer the following question: What is the relationship between the different types of teeth present in an animals mouth and the overall complexity of that animal?
Mikey Ling
(mikeyling@ymail.com)
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ReplyDeleteThe type of teeth an animal has explains its diet. Animals with sharp and pointy teeth are most likely to be carnivores with the need to tear the meat into small chunks. Animals with mostly flat and long teeth are mostly plant eaters or meat eaters that do not need to tear it with teeth. Teeth not only defines diet, but it also defines the flexibility and the joints of the jaw. Animals who cut their food by biting and tearing it between teeth tend to move their jaw in only two directions: up and down (Hillson 13). For animals who need to grind food, such as plant/nut eaters, their teeth will mostly be flat and long, and the jaw will have many more joints. As a result, the jaw will move in four directions: top, down, left, and right. This is the most complex a jaw can get. For example, Sharks, tigers, lions, and jaguars are carnivores with pointy and sharp teeth who tear their food. Their jaw only moves up and down. On the other hand, giraffes, pandas, squirrels, chipmunks, or even humans, have flat and long teeth and both are plant/meat eaters. The movement of the jaw is in four directions in these and other species which allows them to thoroughly chew. To sum it up, animals who have flat and long teeth, and who have the need to thoroughly chew the food are more complex.
ReplyDeleteChandrika D.
(shiningstar0393@gmail.com)
Hillson, S. (2005). Teeth: Second Edition. New York: Cambridge University. Retrieved
March 12, 2011, from Google Books:
http://books.google.com/books?id=hO3OtjMZ3gcC&pg=PA13&lpg=PA13&dq=teeth+and+animal+complexity&source=bl&ots=_Ja99xDg1l&sig=ujD2J_kGIxH8AkZ25Z_RrQQXs1M&hl=en&ei=0V7Tb6GC8jcrAGeoenUBQ&sa=X&oi=book_result&ct=result&resnum=4&sqi=2&ved=0CCQQ6AEwAw#v=onepage&q=teeth%20and%20animal%20complexity&f=false
The shape/type of teeth affect how complex an organism is. If the organism has many canines and incisors then that organism is most likely a carnivore (which are among the most complex organisms). On the other hand, if the organism has many molars, it is most likely a herbivore (or if has no teeth, then clearly it won‘t be as complex of an organism). Shubin explained that “teeth are such a great clue to an animal’s diet…” (61). The diet of an animal is also a good hint to find out how complex it is. For example, the diet of an earthworm is just about anything lying in the dirt, while the diet of a tiger is extremely carnivorous.
ReplyDeleteThere are four distinctive types of teeth: incisors, canines, premolars, and molars. They're the sharpest teeth, built to cut food and shaped to shovel the food inward. Canines are meant for grasping and tearing food. Premolars have a more flat chewing surface because they're meant for crushing food. And molars are much bigger than the premolars and have bigger, flatter chewing surfaces because their job is to chew and grind the food into smaller pieces (http://www.healthyteeth.org/toothGrowth/different.html). Animals with no teeth or almost always shown to be the least complex, such as worms; however, animals with many teeth, especially as they get sharper and sharper (incisors and canines) the animal rises up the food web, proving to get more complex. Chandrika provided plenty examples to explain how complexity rises with teeth (from chipmunks to sharks, etc).
Equally important in determining how complex an organism is, is the fit between upper and lower teeth. When observing tritheledonts, Shubin saw that the individual cusps do not interlock in a precise way as mammals do. Instead, the inner and outer surface sheer against one another like scissors. The way teeth fit together is another factor that leans animals toward or away from certain prey. And as mentioned earlier, the specific prey helps determine the complexity of the organism (the predator).
The material the teeth is made out of changes the complexity of the organism too. Hydroxyapatite “impregnates the molecular and cellular infrastructure of both teeth and bones, making them resistant to bending, compression, and other stresses” (74). The hardness hydroxyapatite gives the teeth, especially the enamel, is what makes our teeth so strong and powerful to crush into food and chew it. Animals like clams and lobsters, on the other hand, don’t use hydroxyapatite for their teeth, but instead use calcium carbonate or chitin. The difference in the material can be equally seen in the difference of the complexity of the animal. Hydroxypatite is found in the most complex of organisms with the strongest teeth, and a lack of teeth is found in the simplest organisms.
-Michelle Layvant, michellel94@hotmail.com
As Chandrika and Michelle have pointed out, the structure of the teeth, as well as their material, can tell us about the complexity of the animal, especially as related to what kind of prey they typically hunt. Teeth of carnivores are typically more "long, sharp, and pointed" (http://www.waoy.org/26.html) for tearing through flesh, while plant-eaters and omnivores typically have flat-edged teeth. Humans, though we are animal-eaters, have flat-edged teeth. This may bring up the question: were we designed to be animal eaters? Is the structure of our teeth more fit for only eating plants? While we may never know for sure, an important aspect to remember is that although we don't have such pointed teeth as those seen in other more predatory animals such as lions, we do have a more complex jaw structure that allows for grinding up and mashing together of food.
ReplyDeleteIn addition to what has already been said about the structure of the teeth in relation to functionality and complexity, another important aspect concerning teeth is that they are particularly helpful in seeing a snapshot into the past lives of animals--when looking at ancient, preserved teeth, studies by George Armelagos of Emory University have shown that "people who acquired tooth enamel defects while in the womb or early childhood tended to die earlier, even if they survived to adulthood" (http://www.sciencedaily.com/releases/2010/02/100204204315.htm). Thus, we can see the importance of our specific tooth structure, especially with the protective outer layer of enamel. This may also be reflected in our everyday behaviors; unlike in the past, it's become proper social behavior to brush our teeth and visit the dentist or orthodontist. These occupations and behaviors have developed from the increasing importance we've put on our teeth; as we can see from these past studies, when our teeth are damaged, this may cause a decreased life span because many digestive functions of our body are inhibited.
An interesting "halfway" development point in the structure of teeth is the gizzard, which is the digestive structure with a "thick muscular wall [that may] contain small stones, or gastroliths, that function in the mechanical breakdown" (http://www.britannica.com/EBchecked/topic/234488/gizzard) of food in animals such s birds and earthworms. These animals don't have the more complex structure of teeth that is seen in humans and other animals, and thus the gizzard may be comparable to teeth in other animals because of its grinding function in breaking down the food further before chemical digestion kicks in.
Sources:
http://www.britannica.com/EBchecked/topic/234488/gizzard
http://www.waoy.org/26.html
http://www.sciencedaily.com/releases/2010/02/100204204315.htm
Kathy Li, kathy2132@gmail.com