Anteaters and Aardvarks: A Nose for Insect Extermination
As unrelated species that have developed parallel traits in isolation from each other, these two animals provide an interesting representation of the phenomenon of convergent evolution. United by their myrmecophagy -- or ant and termite diet -- anteaters and aardvarks are nevertheless separated by an ocean. Aardvarks are native to Africa, named for an Afrikaans word meaning "earth pig." They prefer the floodplains in the southern region of the continent, where they can find water and soft soil for digging. Anteaters are native to Central and South America, where ants abound in the warmer climate.
The two species are also separated by a number of branches in the animal kingdom's genetic tree. Anteaters are part of the order Pilosa, along with sloths. Four anteater species exist, ranging in size from the diminutive silky anteater with a body length less than a foot long to the giant anteater that grows to be about 4 feet (1.2 meters) long. In between are the mid-sized northern and southern collared anteaters, also called tamanduas. Aardvarks, which are distantly related to elephant shrews, have a less extensive genetic tree than anteaters. Their species is the only one within the Tubulidentata order.
Aside from the tongue and snout, anteaters and aardvarks don't have much in common anatomically. Aardvarks are modified ungulates, or hoofed animals, with claws on their forelimbs. Anteaters have paws with large claws, and they have more fur than aardvarks. Anteaters exhibit a peculiar uneven gait to protect their 4-inch (10-centimeter) claws from wearing down. They tuck the claws up under their paws as though balling them up into a fist.
However, the primary difference between anteaters and aardvarks resides inside their mouths. Although they don't have incisors or canines, aardvarks have teeth. Because of the amount of dirt and sand that enters their mouth as a byproduct of rooting around termite mounds and anthills, their teeth continually grow to withstand damage caused by the grit [source: Myers]. For example, nearly half of one dead aardvark's stomach contents was sand [source: Redford]. Anteaters, on the other hand, have a number of primitive toothlike protrusions on the roof of their mouths called papillae, which help the animals grind up the ants [source: Cohn]. Their muscular stomachs take care of any further breakdown needed to digest these insects.
Anteaters and aardvarks evolved with similar mechanisms to follow their shared preferred diets. Yet, they remained distinctive enough so that we don't consider them to be related species. They both just happen to enjoy the scrumptious taste of ants and termites.
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More Great Links
- Cohn, Jeffrey P. "The Allure of Anteaters." Americas. November/December 2007.
- "Giant Anteater." Chicago Zoological Society. (Oct. 2, 2008)http://www.czs.org/czs/Brookfield/Exhibit-and-Animal-Guide/Tropic-World/Giant-Anteater
- Lumpkin, Susan. "Strange Joints: Anteaters, Armadillos and Sloths." Zoogoer. Smithsonian National Zoological Park. November/December 2007. (Oct. 2, 2008)http://nationalzoo.si.edu/Publications/Zoogoer/2007/6/Strange_Joints.cfm
- "Mammals: Giant Anteater." San Diego Zoo. (Oct. 2, 2008)http://www.sandiegozoo.org/animalbytes/t-anteater.html
- Mills, M.G.L. and Hes, Lex. "The Complete Book of Southern African Mammals." Struik. 1997. (Oct. 2, 2008)http://books.google.com/books?id=CavgCweI1nMC
- Myers, Phil. "Tubulidentata." Animal Diversity Web. 2000. (Oct. 6, 2008) http://animaldiversity.ummz.umich.edu/site/accounts/information/Tubulidentata.html.
- Redford, Kent H. "Curious Creatures to Whom the Ant is La Haute Cuisine." Smithsonian Magazine. August 1983. (Oct. 2, 2008)http://www.columbia.edu/itc/tc/mstu4031/ch06/pipes/article.txt
- Roy, Tui De. "The Strangest Creature I've Ever Met." National Wildlife Magazine. June/July 2003. (Oct. 2, 2008)http://www.nwf.org/nationalwildlife/article.cfm?articleId=781&issueId=62