Gopher Tortoise Project
Food Chains
Essential Question: What food chains can exist in one Florida Upland
community?
The gopher tortoise is one of many animals that live in this part of Florida. Many other
plants and animals live in this Upland ecosystem. Some of them provide food for the
tortoise. Some of them feed on tortoise eggs. Some plants and animals have little direct
relationship to the tortoise.
All the species that live in a specific place and interact with other species in that place
make up an ecological community. In ecology, a community is all the populations of
organisms living in a particular area. The term habitat is also sometimes used to
describe an area occupied by an entire community. For example, a specific area of the
Florida Upland may be considered a habitat.
Ecosystems include all the living and non-living parts of an area. The non-living parts of
the ecosystem include rocks, soil, climate, etc. A niche refers to an organism's role or
place in its community. The niche also refers to the organism's place and function in the
food chain or food web. For example, an herbivore (a plant eater), a carnivore (a meat
eater), an omnivore (plant and meat eater), and producers (make energy from the sun)
may all live in the same community. However, they occupy different niches because of
their different feeding behaviors.
Four different communities occupy the Florida school site. The plants and animals in
those four communities are similar, but there are some important differences. Some
animals will be found in only one community in the ecosystem and not in others. This
limitation affects the food available to them. Many of the larger animals, however, will
move among communities when looking for food or shelter.
One of the main ways that organisms interact is through their feeding relationships.
When talking about animals, this is known as a predator-prey relationship. When
referring to plants, it is known as a producer-consumer relationship. In this activity, you
will explore both these relationships within communities on the Florida school building
site. And, you will learn about interactions among the species in the four communities.
This should help you make your final decision about the land use of the new school.
One way to look at the interactions between the organisms in the community is to create
a food web of the ecosystem. Food webs show the flow of energy through the
ecosystem with arrows connecting predators and prey (note that the arrows always point
to the eater not the organism being eaten). This is because the energy from the eaten
organism transfers to the eater.
Gopher Tortoise Project
Example Food Web
Gopher tortoises dig burrows -- typically ranging in size from 20 to 30 feet long and from
six to eight feet deep -- with their shovel-like front legs. Biologists have found some
burrows as big as 40 feet long and 10 feet deep! The burrows are found in dry places
such as sandhills, flatwoods, prairies and coastal dunes or in human-made
environments such as pastures, grassy roadsides and old fields. The gopher tortoise is a
keystone species, meaning its extinction would result in measurable changes to the
ecosystem in which it occurs. Specifically, other animals, such as gopher frogs, several
species of snakes and several small mammals, depend on tortoise burrows. For the
gopher tortoise to thrive, the animal generally needs three things: well-drained sandy soil
(for digging burrows), plenty of low plant growth (for food) and open, sunny areas (for
nesting and basking).
As in all of these communities, the smallest inhabitants of the sandhills are the insects.
They feed on a variety of plants, including pines and saw pawpaw, as well as other
insects. Insects, in turn, are eaten by birds that nest among the plants. Besides the
insects, squirrels and rabbits also eat plants and seeds. In the fall, the saw pawpaw
fruits ripen and provide food for opossums, gopher tortoises, and squirrels. When the
gopher tortoises lay their eggs, raccoons and gray foxes eat some of the eggs before
they hatch. Birds that nest close to the ground may also lose their eggs to snakes. The
snakes will also find plenty of frogs and mice to eat. The frogs survive on insects, while
mice prefer to eat wiregrass and other types of vegetation. Insects eat pine and
palmetto. Large mammals, such as hogs and bears, eat the palmetto. Besides the
palmetto, bears eat snakes, armadillos, and hogs. The endangered Florida panther is
sometimes seen in the flatwoods, where it hunts armadillos and hogs. Armadillos eat the
smallest members of the community, the insects.
Gopher Tortoise Project
Community Descriptions
The communities described below are sandhills, scrub, scrubby flatwoods, and
flatwoods. The scrub is at the highest elevation, and is therefore the driest. The
flatwoods community is the wettest and is at the lowest elevation. All the communities
have very sandy soil.
Sandhills
Sandhill plant communities cling to sandy ridges. Longleaf pine trees provide a treetop
canopy, while grasses such as wiregrass and saw pawpaw make up the understory, or
the underlying layer of vegetation. Periodic fires, which usually occur every four to seven
years, are essential to maintaining this plant community. This is because pine seeds
germinate well after being exposed to fire.
Gopher Tortoise Project
Flatwoods
South Florida flatwoods occur on nearly level land. Water movement is very gradual to
the natural drainageways, swamps, marshes, and ponds associated with this
community. During the rainy season, usually June through September, this site may
have water on or near the soil surface. It is easily recognized by the flat topography and
slash pine and saw-palmetto vegetation.
The landscape position of this range site affects plant-water relationships and causes
slight differences in plant composition from wetter to drier areas. The natural vegetation
of this site is typically scattered pine trees with an understory of saw-palmetto, gallberry
and wiregrasses. The relative percentages of annual vegetative production by weight for
this range site are grasses and grasslikes 75%, woody plants and trees 15%, and forbs
10%.
The south Florida flatwoods are well suited for deer, quail, and turkey. It is fair for
squirrels and well suited for many songbirds, particularly warblers. It is also well suited
for bobcat, skunks, opossums, and raccoons.
Some of the threatened and endangered species found in the flatwood communities are
the Florida panther, mangrove fox squirrel, eastern indigo snake, gopher tortoise, striped
newt, Miami black-headed snake, mole snake, and a number of birds and plants.
Gopher Tortoise Project
Scrubby Flatwoods and Scrub
Scrubby flatwoods have a shrub layer of saw palmetto scrub but and a canopy of
flatwood pines. Scrub vegetation is associated with ridges of well drained to moderately
well drained soils similar to coastal dunes. Florida scrub vegetation includes several
distinctive but related vegetation types. These include sand pine scrub, rosemary scrub,
saw palmetto scrub. These sites are often subject to periodic fires that help the pines
sprout and grow new trees. Animals that occur in scrub include the Gopher Tortoise,
Florida Scrub Lizard, Eastern Indigo Snake, and Florida Mouse. All of these are on
threatened or endangered animal’s lists.