Download Gopher Tortoise - Cincinnati Zoo

Gopherus polyphemus
Gopher Tortoise
Class: Reptilia. Order: Testudines. Family: Testudinidae.
Other names:
Physical Description: The gopher tortoise is a terrestrial turtle with a
domed shell and round, stumpy, elephantine hind legs that are welladapted for digging. The carapace is brown to tan, with light-centered
scutes; they usually have a yellowish plastron, grayish brown head, and dark brown irises. Head is large
and blunt in front; hind feet are smaller than front feet; male plastron is concave. Adult gular scutes
project beyond carapace, serving as a “head rest”, which is convenient, since they cannot pull their head all
the way into their shell. They typically are 9¼ - 14½” in length, and weigh from 8-15 pounds.
One of the most unique features of turtles and tortoises is their protective shell. Because of the shell,
flight, running, and climbing are not evolutionary options! But some adaptive radiation occurs within the
order. Turtles and tortoises inhabit marshes, lakes, rivers, and the open sea, as well as forests, grasslands
and deserts. The top shell is called the carapace and the bottom shell the plastron. The carapace develops
from a layer of skin and the backbone and ribs are fused to the carapace. The plastron is developed from
the bones of the shoulder girdle. The shell is so successful that it is the cornerstone of turtle design and
lends to the lineage’s longevity, while at the same time limiting species diversity.
Diet in the Wild: Generally herbivorous: grass, leaves, wild fruit; may eat some insects; in captivity they
readily accept leafy greens, vegetables, and fruit; some show an interest in meat.
Diet at the Zoo: Tortoise biscuits, mustard greens, collard greens, escarole, romaine, sweet potato, carrot.
Habitat & Range: Well-drained sandy areas between grasslands and forests. Found along the southern
coast from South Carolina to Florida and along the Gulf Coast to extreme eastern Louisiana. They dig long,
wide burrows which may reach 35 feet in length.
Life Span: Up to 80 years in the wild (typically 40-60 years); up to 100 years in captivity.
Perils in the wild:
Some mammals and birds of prey eat hatchlings.
The automobile takes its toll each year as the slow-moving turtle attempts to creep across busy
streets, highways, and railroad tracks.
The biggest peril is from habitat destruction and/or fragmentation (which is defined as habitats
separated by human land usage) causing small, isolated populations that sometimes suffer from
inbreeding.
Physical Adaptations:
Heavily scaled forelimbs, when folded, close the opening of the shell and provide good protection
for the head and neck.
Gopher tortoise’s have front feet that are well adapted to digging their burrows, and elephantine
rear feet for walking. This type of foot adaptation is common in terrestrial turtles and tortoises.
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See “physical description” above for more information on the design of the turtle’s shell.
Behavioral Adaptations:
Diurnal. Typically emerge from burrow when the day gets warm and feed until early afternoon.
Mostly solitary and territorial. Most gopher tortoises will occupy the same burrow for most of, if
not all, of their life.
Gopher tortoises are accomplished burrowers, having immovable wrists that give their forelimbs a
shovel-like movement and great power. Their tunnels slope downward from the surface and then
usually level off underground, and may be up to 35 feet long and wide enough so that the animal
may turn around at any point along its length. The burrow, which is a permanent home, is kept
painstakingly free of debris. The very stable temperature and humidity within the burrow protect
the tortoise from the alterations of climate which may occur on the surface. Because the weather
in their range is cooler and more humid, gopher tortoises may remain active through the hottest
hours of the day. They enter short periods of hibernation only if the weather becomes severe.
Reproduction and Development:
Gopher tortoises are slow to reach sexual maturity – at 10 to 20 years of age. They have a low
reproductive rate, and a total of only 3-5% of their young typically survives.
The breeding season typically spans March-December, but most eggs are laid during May and June.
When courting, a male gopher tortoise will circle the female and bob his head up and down to
attract the female. When this succeeds, the male then bites the female on the leg and the front
edge of the shell, which usually initiates mating.
Females deposit 1-25 (typically 5-8) white, spherical eggs at the entrance of their burrows to
capture heat, making them prey to raccoons and other predators. After an incubation period of 80110 days, depending on latitude, the eggs hatch and the young dig their way to the surface.
Hatchlings are 1 ½” in length with large yellow or orange spots on their carapace.
Additional Information:
The gopher tortoise is a keystone species, which is a species that has a disproportionally large effect
on its environment. Keystone species play a critical role in maintaining the ecological community
where they live through their effect on the ecosystem and the other plants and animals that live
there. For the gopher tortoise, this is mostly due to the diverse group of animals that utilize and
depend upon the burrows created by the gopher tortoise.
Many other animals seek shelter or live permanently in “gopher” burrows. These run the gamut
from insects to burrowing owls, raccoons and opossums, gopher frogs, indigo snakes, diamondback
rattlers, toads, and various invertebrates. As such, gopher tortoises are very important animals in
their ecosystem, and are considered a keystone species.
Like the desert tortoise, gopher males are normally placid except during the mating season. When
two males meet, they nod their heads rapidly and perhaps touch noses before continuing their
separate ways. However, during the mating season, a fight may ensue. Each draws back and then
rushes toward the other, using the gular scute projecting forward from the plastron to butt one
another in the hopes of tipping over one’s adversary.
According to one source, certain Indian tribes once used the gopher tortoise as a form of money. Its
shell was used to make baskets and pots.
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Conservation Status: IUCN Status
The IUCN has assessed the gopher tortoise as “Vulnerable” (VU) – High risk of endangerment in the wild.
The tortoise is listed as a Threatened Species under the U.S. Endangered Species Act and is protected by
State law in many of its range states.
Conservation Efforts:
There are conservation efforts underway to protect the gopher tortoise’s habitat in the Southeastern
United States. One organization, “The Gopher Tortoise Council”, offers professional advice for
management, conservation, and protection of gopher tortoises; it encourages the study of the life history,
ecology, and management of gopher tortoises and other upland species, and also conducts active public
information and conservation education programs, and seeks effective protection of the gopher tortoise
and other upland species throughout the southeastern United States.
Glossary: List of definitions of the most important recurrent technical terms used in the text.
Carapace - The top shell of a turtle. The carapace develops from a layer of skin and the backbone and ribs
are fused to the carapace.
Diurnal – Active during daytime hours.
Gular scutes – Enlarged scales on the plastron of a turtle which are located under the throat.
Keystone species - A species that has a disproportionally large effect on its environment, and plays a critical
role in maintaining the ecological community where they live through their effect on the ecosystem and the
other plants and animals that live there. Named after the architectural term “keystone,” which refers to
the wedge-shaped stone at the very top, or apex, of a masonry arch, which supports and essentially
upholds the entire arch. Often, if a keystone species is removed from the ecosystem, a cascade of events
occurs that greatly impacts the ecosystem (e.g. if a keystone predator is removed, its prey population
explodes, which then overgrazes the local plant life, etc.).
Plastron - The lower shell of a turtle, developed from the bones of the shoulder girdle.
Scute - Any enlarged scale on a reptile; sometimes called a “plate”.
Vulnerable (VU) – IUCN status which defines a “High risk of endangerment in the wild”.
Sources:
Cincinnati Zoo & Botanical Gardens
http://www.benning.army.mil/garrison/DPW/EMD/gopher_tortoise.htm
http://www.fws.gov/northflorida/GopherTortoise/Gopher_Tortoise_Fact_Sheet.html
http://naturalhistory.uga.edu/~GMNH/gawildlife/index.php?page=speciespages/species_page&key
=gpolyphemus
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