Good Example Of Research Paper On Nine-Banded Armadillo (Dasypus Novemcinctus)

Introduction

Armadillos are mammals that have bony plates covering much of their body. They are the only known living mammals to wear these plates. Their shield-like shells led these animals to obtain the Spanish name armadillo, which in English translates to “little armored one.” There are 20 recognized varieties (with multiple subspecies) of armadillos and all but one can be found primarily in Latin America (Mengak, 2004).
The nine-banded armadillo (Dasypus novemcinctus), aka long-nosed armadillo, can be found in North, Central, and South America, and is the most widespread of the armadillo species (Smith, 2007). They are primarily found in forests and scrub-brush areas of tropical and temperate regions, but may also reside in grasslands and savannas near wooded areas and streams (McDonald and Larson, 2011; Mengak, 2004). They are more common in warm and humid areas and prefer some forest cover for foraging (McDonald and Larson, 2011; Smith, 2007). They are a very adaptable species, enabling them to colonize a wide range of habitats.

Background and Description

Armadillos have been mentioned in a Mayan legend that recounts their creation by the Mayan Sun God to teach humility to two minor gods. The two unruly gods sat down on a bench that was transformed by the Sun God into two armadillos. The armadillos jumped in the air and the disobedient gods fell down and were embarrassed in front of all the other gods present. Historically, the existence of the nine-banded armadillo can be traced back to as early as the 4th century through records of native hunters in Mexico (Taulman and Robbins, 1996). The armadillo was first recorded in the United States in 1854 in southern Texas (Humphrey, 1974). Another source cites a later discovery in 1880, still in the south parts of Texas (Smith, 2007).
The nine-banded armadillo shares the basic characteristic of all armadillos: an armor or shell (carapace) comprised of bony plates covered by leathery keratinous skin. The carapace has three sections: two immobile plates called the pelvic and scapular shields, and movable bands separated by a thin layer of skin and hair around the midsection. There are usually nine visible bands but the number may actually range from 7 to 11. The armor covers most of the armadillo from head to toe, except for the ears and the underside (belly). The ears are hairless and are covered in rough, bumpy skin. The belly has a paler color, appearing pinkish or yellowish, and is covered with coarse grey hair. They weigh about 8 to 17 lb and have lengths of about 2 to 2.6 ft, with the males being larger than the females. They have short legs with four toes on the forefeet and five toes on the hindfeet; also, all toes have thick claws. They have small, peg-like, V-shaped “teeth” that lack enamel and continue to grow throughout the animal's life. Their tongue is long and sticky. Finally, they maintain a low body temperature of 30°C to 35°C and have a relatively low basal metabolic rate of about 384.4 kJ per day (McDonald and Larson, 2011; Smith, 2007; Mengak, 2004; Avila, 1999).

Life Cycle

The life expectancy of nine-banded armadillos ranges from four to over 20 years and is affected by environmental conditions (temperature, nourishment availability, etc.), disease, and predation (Avila, 1999; McDonald and Larson, 2011). They reach sexual maturity when they reach a year old and their breeding season occurs between the months of June and August but can occur as late as December. Implantation of the fertilized ovum to the uterine wall may be markedly delayed (hypothesized to be stress-induced) which can last up to 14-16 weeks. A single fertilized ovum can split into four separate embryos, all of which are identical in genetic makeup. Gestation lasts 150 days or longer and the female usually produces only a single litter per year. Young are born in March or April with their eyes open, and each weighs about 3-4 ounces. Their armor plates are soft and flexible. They learn to walk within a few hours after birth but remain in the nest for a few weeks, after which they accompany the mother while foraging (McBee and Baker, 1982; Mengak, 2004).

Behavior

Nine-banded armadillos are largely nocturnal but may occasionally show activity at dusk or during daytime, depending on weather conditions. They have not been observed to hibernate. They are burrowing animals and may have different burrows for varying functions such as for nesting or food storage. However, nests may also be made above-ground in crevices using twigs and leaves. Their burrows are usually between one to five meters in length and may be as shallow as a few centimeters below the soil surface or as deep as a few meters underground. Nine-banded armadillos are usually solitary animals and usually do not share burrows, except for mating partners or a female and its litter. However, adults may share burrows in cold weather for warmth (Avila, 1999; Smith, 2007; McDonald and Larson, 2011).
Nine-banded armadillos are able to jump three to four feet vertically. This ability has been attributed to increased fatalities of armadillos near roads—an oncoming vehicle may startle an armadillo on or near the road which causes it to jump and be hit. Another observed ability of this armadillo is the way it crosses bodies of water. In shallow or narrow bodies of water it can simply walk across the bottom, as it can hold its breath for up to six minutes. It can also swim across or float across by gulping air (Avila, 1999).
Aggression is not commonly observed among members of this species, but pregnant or a mother with its young may exhibit protective behavior. During mating season males may show aggression towards younger or smaller males, but this is most probably for intimidation and does not result to fatalities. Threatened individuals usually seek a burrow or a thick brush to hide in. They may also curl up to use their armor for protection but cannot fully enclose themselves in a full ball (which can be done by the three-banded armadillo) (McDonald and Larson, 2011).

Feeding Habits

Nine-banded armadillos are considered generalists as they eat a wide range of food items. A large part of their diet comprises of insects such as beetles, termites, centipedes, millipedes, ants, grasshoppers, etc. They also feed on other invertebrates, small reptiles, amphibians, baby mammals, and bird eggs. They have also been observed to eat carrion. Less than 10% of their diet includes fruit, seeds, fungi, and other plant matter. They rely on their strong sense of smell (as they have poor eyesight) while foraging in order to locate food. They spend most of their time above-ground foraging, which is hypothesized to explain the lack of altruism between littermates and their solitary nature (Smith, 2007).

Evolution

Information of the evolution of the nine-banded armadillo is not as extensive as other mammals. However, their ancestry can be traced back to the armadillo-like creatures: glyptodon and panocthus. They were as big as a car and were also armored. They resided in what is now South America but soon faced extinction with the arrival of predators from northern lands through a newly formed land bridge. The ancestral armadillos moved northward to escape predation. The beautiful armadillo (Dasypus bellus), which most closely resembles the nine-banded armadillo but three times bigger, flourished near the Ohio River valley until about 11,000 years ago when they became extinct (Nixon, 2012). Their gradual decrease in size may be a response to predation, so that it increases chances of escaping predation by increasing agility and introducing the ability to burrow underground. The armadillo then became re-established in the US in the 1800s.

Additional Interest

Nine-banded armadillos are consumed by humans and is said to be similar to pork in terms of texture and flavor. Various parts of the animals are also utilized to combat medical conditions in some Latin American communities. They help reduce pest populations by consuming insects but are considered slight pests through their burrowing and foraging activities that interfere with agriculture. Moreover, they are used in scientific studies for medical research, especially for the disease leprosy, as armadillos are the only animals apart from humans that are known to carry the bacterium (Mycobacterium leprae) that causes it (Smith, 2007).

Conclusion

The armadillo is a small mammal characterized by its hard armor of bony plates. The nine-banded armadillo (Dasypus novemcinctus) is the most widespread species of armadillo and can be found across the United States. It prefers warm, humid habitats because it cannot tolerate cold weather well. It also prefers forests for more successful foraging and feeding opportunities. It is also more commonly found in areas close to water and cannot survive in xeric environments. They most probably evolved from the beautiful armadillo that went extinct 11,000 years ago. They are consumed by humans and are hunted as wild game by certain communities. They find importance in medical research for various human diseases.

References

Avila, R. (1999). The Biogeography of the Nine-banded Armadillo (Dasypus novemcinctus). San Francisco State University. Retrieved from http://online.sfsu.edu/bholzman/courses/Fall99Projects/armadillo.htm
Humphrey, S.R. (1974). Zoogeography of the Nine-Banded Armadillo (Dasypus novemcinctus) in the United States. BioScience 24(8): 457-462.
McBee, K. and Baker, R.J. (1982). Dasypus novemcinctus. Mammalian Species (162): 1-9.
McDonald, K. and Larson, J. (2011). Dasypus novemcinctus. University of Michigan. Retrieved from http://www.biokids.umich.edu/accounts/Dasypus_novemcinctus/
Mengak, M.T. (2004). Nine-banded armadillo (Dasypus novemcinctus). USA: USDA National Wildlife Research Center - Staff Publications.
Nixon, J. (2012). Armadillos. Retrieved from http://armadillo-online.org/armadillos.html
Smith, P. (2007). Nine-banded armadillo: Dasypus novemcinctus Linnaeus, 1758. Retrieved from http://www.faunaparaguay.com/mamm8Dasypusnovemcinctus.pdf
Taulman, J.F. and Robbins, L.W. (1996). Recent range and expansion and distributional limits of the nine-banded armadillo (Dasypus novemcinctus) in the United States. Journal of Biogeography 23(5): 635-648.