DISCOVERY HALL
The Tennessee Aquarium celebrates the rivers of the world by offering
visitors an opportunity to observe and explore a variety of habitats associated
with rivers. Discovery Hall goes one step further by giving visitors an even
closer look at fascinating aquatic microcosms.
The habitats within Discovery Hall are as unique as the animals. Some
make their homes in rivers, lakes or streams, while other call swamps and
wetlands home. These exhibits will bring you up close and personal to the often
unnoticed creatures of our region. Although many are small in stature, their
role in the ecosystem is large. They warn us of disturbing conditions in our
environment simply by their presence or absence. Others tell a story of time
past when their populations were large and their habitats healthy. Stroll
through this gallery and discover the wonders within.
Exhibits of Discovery Hall
Sunfish Celebration
Swamp Nursery
Frogs are Disappearing
Pascagoula Bayou
Bottom Dwellers
Night Voices
Southern Spring Run
Estuary
Sturgeon Encounter
Sunfish Celebration
The sunfish, as their name implies,
are some of the most vibrant freshwater
fish. Smaller species often display the
most striking patterns. Hues of orange,
yellow, blue, green and gold complement
the spots, bands and other delicate markings. Colors become even more vivid during
the breeding season as the fish ready themselves
to attract mates.
Bluespotted Sunfish
These aquatic rainbows play a vital role in the web of life of an aquatic community. They prey on insect larvae, crustaceans and other invertebrates and, in turn, are
fed on by larger fish, birds and mammals. Sunfish are recognized by almost everyone,
although several species have fascinating qualities that make them unique. Bluespotted
sunfish live among dense vegetation in slow-moving streams. This lovely sunfish has
iridescent blue spots against a dark background. They feed on snails, insects and other
organisms. Sunfish have elaborate breeding and nest guarding behavior. Many males
guard and protect their nests from invasion by predators.
Golden Topminnow
Topminnows, as their name implies,
spend most of their time cruising just below
the surface. Their top feeding preference is
demonstrated by their upturned mouths.
Although small, topminnow males are
beautifully patterned to attract females. The
golden topminnow grows to less than three
inches and is a golden color. Breeding males
have red spots scattered on their bodies. They
feed on insects from the surface.
Like other aquatic species, their brilliance doesn’t protect them from feeling the
effects of changes in their habitat. Destruction of streambeds, dredging and runoff has
taken a toll on the population. Only through conservation efforts can we continue to
enjoy these dazzling denizens of our streams.
Swamp Nursery
Chirp, chirp, chirp! Not the sound you might expect
from a gator nest, but when a baby sends this distress signal,
you can be certain Mom’s on her way! Growing up in a swamp
can be dangerous and, luckily for baby gators, female gators have great
parenting skills. In fact, alligators are one of the few reptiles to provide any form of
parental care for their young.
Courtship of adult gators begins from mid-February through April and they
typically nest two months after mating. Nests may contain anywhere from 20 – 60 eggs.
Incubation lasts for 65-70 days, depending on the temperature.
Baby alligators begin life enclosed in protective eggs buried deep inside large
nests. Each oval egg is about three inches long and less than two inches wide. The baby
gator is nourished by its yolk sac inside the egg. The nest protects the eggs from predators, and keeps them moist. The temperature determines
whether they hatch as males or females. Temperature dependent sex determination is a fascinating aspect of nature.
Eggs incubated at higher temperatures (more than 90o)
typically hatch male babies, while cooler temps (below 85o)
hatch females. Just prior to hatching, the egg tooth forms
that allows the baby to slice its way out of its egg. Baby alligators are about eight inches in length at hatching and typically
have black and yellow banding patterns on their back. This pattern aids in their camouflage. During their first four or five years, they grow slowly,
usually less than a foot per year.
After hatching, females carry their young to the water inside their cavernous
mouths. Pretty safe place if you’re a baby gator. Juveniles begin life in the swamp
hunting for anything they can catch from insects or worms to fish and tadpoles. The
swamp is full of dangers including egrets, herons, bass, otters, raccoons and other alligators. When predators threaten, the babies head for the safety supplied by their mothers.
The range of American alligators extends south from coastal swamps in North and
South Carolina through the coastal areas of Georgia to Texas and Florida. Alligators
spend the majority of their time basking on banks and overhangs of swampy
areas. When submerged, they have a protective membrane
that covers their eyes. The size of the alligator
and the temperature of the water play a
role in determining how long it can stay
submerged. During warm months, they
can remain submerged about 45 minutes;
cooler water slows their metabolic rate
and allows them to stay under longer.
Frogs are Disappearing...
In 1989, the last golden toad was seen in the cloud forests of Costa
Rica. It is now extinct.
Amphibians face many threats, habitat loss, climate change and pollution but
the most immediate danger is a deadly parasitic fungus. Called amphibian chytrid, it is
responsible for the extinction of dozens of frog species over the past decade. It has
spread from Africa around the world to even occurring in 20 states in the U.S. What
does this mean? The predicted loss of one-third of the world’s amphibian species. Immediate captive management is one stopgap measure of an integrated conservation effort
to save certain species. To learn more about this problem visit www.amphibianark.org.
Blue poison dart frog
Dendrobates azureus
Range: Surinam
Size:
1 3/4 inches
Yellow and blue poison dart frog
Dendrobates tinctorius
Range: Surinam, Guyana,Brazil
Size:
2 1/4 inches
WOW!
In captivity, these species
lose their poisonous properties
due to a lack of toxic compounds
within the food it is fed. In the
wild, formacine ants provide
the chemicals to synthesize
toxins.
Yellow-banded poison dart frog
Dendrobates leucolmelas
Range: Venezuela
Size:
1 1/2 inches
Giant Waxy treefrog
Phyllomedusa bicolor
Range:
Amazonian Peru and Brazil
Size:
4 1/2 inches
The Giant Waxy or Monkey tree frog is a large, nocturnal, bright green frog. It is
an insectivore that crawls hand over hand in search of crickets and other insects to eat.
Their common name is derived from two behaviors. “Waxy” refers to the lipid secretions
they spread over their bodies to prevent water loss and “monkey” refers to the opposable thumb they use to better grasp the branches as they climb. These animals spend
the daytime sleeping high in the canopy off the rainforest floor.
Pascagoula Bayou
The lower sections of the Pascagoula
Longnose Gar
River wind through the bayous under a canopy
of Spanish moss. These quiet, slow moving aquatic communities serve as a nursery
for many animals. Hatchling turtles, such as the endangerd yellow-blotched map
turtle, find refuge among the forest of water plants. Juvenile fish also seek shelter
and feast on crustaceans, mollusks and insect larvae. In this habitat, young sunfish
assume their natural position in the water as topminnows skim the surface and gar
and pickerel lie in wait below. These predators remain motionless as they attempt to
ambush an unsuspecting meal.
The species of sunfish in this exhibit range in size from 4-6 inches. The orange-spotted sunfish develops a bright yellow or orange breast and belly, while the
longear sunfish turns a bright orange highlighted with blue all over. The dollar
sunfish develops patterns of iridescent blue tones. After spawning occurs during the
spring and summer, the males guard the nests and fry as they hatch.
There are four species of gar that occur in Tennessee. These primitive fish are
covered with rough diamond-shaped scales that provide additional protection. Gars
have a vascular swim bladder connected to their esophagus that allows them to
breathe oxygen from the surface. Gars spawn in late spring and eggs are laid and
adhere to vegetation. The young have an adhesive disk near the tip of the lower jaw
that they use to hang on to plants until the young absorb their yolk sac. Once they
begin feeding on their own, they eat insect larvae and microcrustaceans. Juveniles
have a broad dark stripe along the side of their body and an extension of their vertebral column can be seen just above their caudal fin. Adult gars are piscivorous,
meaning they feed on other fish.
Young turtles spend most of their time feeding on aquatic insects found in the
vegetation and basking on logs along the river’s bank. As the turtles grow, the difference between males and females becomes very obvious. Female map turtles grow to
be almost twice as big as males and develop slightly different diets. Because females
require more calcium in their diet for egg production, they tend to eat more shelled
invertebrates such as clams, mussels and snails. Because map turtles have very
specialized diets, they are more sensitive to water pollution and siltation of river
bottoms.
The yellow blotched map turtle is a federally
threatened species found only in the Pascagoula
River watershed. Juveniles and adult males
have a black spine on the first four vertebral
scutes. Females grow to about 8 inches in
length, while males remain smaller at a maximum size of 4 ¾ inches. These turtles prefer
river habitats with numerous basking sites
Yellow-blotched map turtle
where they may remain for several hours at a
time. Females typically lay 3-4 clutches of 5-6
eggs a year.
Bottom Dwellers
It’s large, it’s slimy, it’s completely harmless. What is it?
None other than the hellbender, the largest salamander
found in North America. The hellbender is one of only
three species of giant salamander, the others are found
in Asia. These cryptic creatures can grow to more than
two feet in length. Captive hellbenders have lived 29
years, but their life span in the wild is unknown. HabiHellbender
tat destruction and pollution have reduced hellbender
populations.This unusual animal lives a solitary life
among the rocks of cold, clear trout streams. The body and head of the hellbender are
flattened and wrinkled. There are flaps of loose skin along the lower sides of the body
and the color can vary from gray to black with irregular spotting. It has no lungs and
breathes through its skin.
The hellbender’s voracious appetite leads it to consume almost any aquatic animal small enough to swallow, including insects, earthworms, crayfish and snails. Hellbenders are totally aquatic and are found in clear rivers and fast-moving streams with
rocky bottoms. Since they are nocturnal, these salamanders must find ample daytime
shelter in the form of large rocks or other stream debris. The hellbender’s range is from
New York south into Alabama and Georgia.
The softshell turtle is a powerful swimmer and quite agile on land on the
rare occasion it ventures from its aquatic home. Thick webbing on their feet allow
them to evade predators in the water. Softshell turtles are aptly named for their
soft, leather-like shell that lacks the scales or scutes typical of most turtles. Its
flattened shape allows this turtle to bury itself in the substrate leaving only a tiny
portion of its head visible. Their sharp claws and strong jaws assist them in preying on small fish, insects and crustaceans.
Night Voices
A quiet evening can be suddenly transformed into
a concert hall as the night explodes into a chorus of frogs
and toads. Each species has its own call that encompasses
a wide range of pitches, tones and rhythms.
Unversed in frog talk, the human ear may mistake
a frog chorus as random and chaotic noise. In actuality
this cacophony is a fascinating, complex network of
species specific communication. Like many other animals,
frogs and toads can communicate different messages
through variations in vocal signals.
Treefrogs
Frog and toad calls can express alarm, distress,
feeding behavior or reproductive readiness. Females
respond to the calls of males eager to mate and soon new life will
invade the pool as hundreds of tiny eggs are laid in the water. Only a small percentage
will actually survive to become adults as aquatic predators find the eggs a tasty snack.
Well adapted for their arboreal existence, treefrogs have long limbs and digits
that help them cling to twigs and bark. Both the adhesive pads on their toes and the
rough skin on their bellies help them “get a grip” on slippery surfaces. While there are
some treefrogs that live high in the treetops, most prefer brushy thickets, swamplands,
and moist woodlands. These amphibians are able to change the color of their bodies in
response to light, temperature and the colors and patterns of their surroundings.
The barking treefrog is one of the larger species with its stout, rounded body
reaching a length of two inches. A good way to identify the barking treefrog from other
species is to look for profuse round, dark markings that
usually persist through various color changes. A generalist when it comes to living space, it is both a high
climber and a burrower. In hot, dry weather the barking
treefrog seeks shelter in sand or soil beneath roots or
clumps of grass. The barking treefrog gets its name
from the sound of its call — it actually barks! This call
of 9 or 10 raucous syllables is uttered from the treetops.
Barking Treefrog
The green treefrog has a pointed snout and a streamlined body shape. It is a beautiful shade of bright green, with
a broad white or gold line down either side of its body. When clinging to a branch or
leaf, this treefrog tucks all four legs under its body and looks like a smooth, damp, green
bump with eyes. Sometimes called the “bell frog,” the green treefrog’s call sounds like a
bell and may be repeated as many as 75 times per minute. The green treefrog is primarily a nocturnal creature, but you might catch a daytime glimpse of one if you take a
peek at the underside of a large leaf. Secured with its sticky toe pads, the frog is shaded
from sunlight and hidden from predators. Green treefrogs are frequent visitors to windows at night where they seek out insects that have been attracted by the light. The
green treefrog is known as a “rain frog”, an indigenous name shared by many other
treefrogs. It is believed that these amphibians are weather prophets, singing lustily
before and during damp or foul weather!
Southern Spring Run
Aquatic plants play a vital role in the health of southeastern streams. Many
plants have unique adaptations that allow them to thrive under water. Some have
pockets in their leaves that help them float, others use specialized root structures to
remain anchored in the bottom. Plants provide many functions within the aquatic
community. Their main role is providing oxygen for
the other organisms that live in the stream.
Through the process of photosynthesis, plants
utilize carbon dioxide in the water and release
oxygen. Many plants serve as nursery grounds
for young organisms. Small organisms use the
stems, roots and leaves as homes. Many plants
are eaten by a variety of aquatic
Sailfin Shiner
animals. Along the shore, plants serve to
stabilize the shoreline and prevent erosion. Some plants such as water hyacinth
absorb excess nutrients and even toxins from streams making them cleaner places for
animals to live.
Swimming among the lush landscape, shiners provide movement and color that
rival many tropical species. These fish, found in the family Cyprinidae, are often
simply called minnows. Tennessee is home to nearly 80 species of this type of fish.
Most of these fish are beautifully colored with striking stripes, spots or other patterns.
Taillight Shiner
While the term minnow typically evokes an
image of a tiny stream fish, some members of
this family, such as the common carp grow
quite large. Most of the Tennessee species
rarely exceed five inches in length. Shiners
are adapted for living in a wide range of
freshwater habitats. They eat algae, aquatic
insects, microcrustaceans, fish fry and detritus. While they don’t have teeth in their jaws,
these fish have pharyngeal, or throat teeth.
These teeth are located back in the throat and
function to hold, tear and grind food items.
Shiners spawn in spring or early summer either using hollowed-out gravel nests
or randomly over the substrate. The taillight shiner has a distinct dark spot on its
caudal peduncle. Breeding males develop bright orange-red bands along their body
and spots on the fins and operculum. This species prefers habitats with dense vegetation. They typically do not live more than one year.
Estuary
Eventually the river must meet the sea and the point at which one encounters
the other is called an estuary. In this complex and ever-changing habitat, freshwater
and saltwater animals abound. Estuaries serve as a nursery and feeding ground for
many marine species. Animals inhabitating the estuary are faced with the challenges of
fluctuating salinity, water levels and food. Each species is adapted in fascinating ways
to the ever-changing conditions.
The beautifully patterned diamondback terrapin is
the only North American turtle species to inhabit the
brackish water systems between freshwater
habitats and the ocean. They can be found
along the eastern seaboard from Massachusetts, around the panhandle of Florida and
across the Gulf Coast to Texas. Reaching a
length of 10 inches, this turtle has a dark
gray carapace and a cream-colored plasDiamondback Terrapin
tron. The skin color on its head and feet is a
spotted, smoky gray.
Terrapins feed on a large variety of crustaceans, fish and insects and spend most
of their time in the water, coming to shore only to bask and lay their eggs.The female
diamondback terrapin is able to store sperm in her body and does not need to mate
annually. Like sea turtles, female diamondbacks deposit their eggs in sandy nests
above the high water mark on a beach. Although predators such as sea gulls and foxes
eat a majority of the eggs, many will survive to return to the water. Unfortunately,
these unique animals face serious threats from estuarine pollution and drowning in
commercial crab traps.
Conservation Note
Diamondback terrapins are perhaps best known for their meat which
became a popular gourmet food item from the late 1800s to the early 1900s.
They were such a sought after commodity that large terrapin “farms” were
established to meet the demand. Luckily for the terrapin, its popularity as
a delicacy was only a fad and the natural populations have since made a
comeback. Ironically, the farms that were in the business of supplying
terrapins for the dinnerplate saved some populations from becoming
extinct. These farms raised the animals as well as decreased the
pressure on wild populations.
Diamondback terrapins sleep buried in the mud at night, and spend much of their
day scavenging for food. Their diet is varied and includes small fishes, crustaceans,
insects and mollusks. The powerful jaws of this turtle can easily crush the shells of snails
and clams.
The gulf killifish lives in a habitat of
constant flux as the ocean tides shape its existence. Found in tidal flats, grassy bays and canals,
this small fish inhabits the Gulf of Mexico region
from northeast Florida to Cuba. The gulf killifish
Gulf Killifish
has a blunt head and an upturned mouth identifying it as a top feeder. The back is dark with a
slightly yellow underside. Many small pale spots may be seen along with faint body bars
along its side. Like many fish, the killifish exhibits a change in color during the breeding season. The male will become orange-yellow on the underside with black cheeks.
They feed on a variety of prey including blue-green algae, juvenile fish and insects.
Killifish have increased in value as bait fish over the years and they are a very important biological control of mosquitos.
Hermit Crab
Have you ever seen a naked hermit crab? Your
answer is probably no because these long, soft asymmetrical crabs are seldom found outside the shelter of
their adopted home, an old snail shell. As the crab
grows, it requires a larger and more spacious shell
because too tight a fit will result in decreased
growth rates. In the struggle to find a shell of suitable size, a larger crab may evict a smaller one from
its shell.
A flash of iridescent blue in the sandy, shallow
waters of coastal marshes and tide pools may indicate
the presence of the male sheepshead minnow. This
robust fish which measures a mere 3 inches in length
rarely frequents water of more than a few feet deep. It
is extremely adaptive to drastic changes in temperature
Sheepshead Minnnow
and salinity. It has been known to enter freshwater and
can even survive in water with 4 times the salt content of
regular sea water. Its geographic range is far reaching, extending from
Massachusetts to northern Mexico.
Sturgeon Encounter
The lake sturgeon is one of eight species of
sturgeon native to North America and one of 27
sturgeon species worldwide. The historical range
of lake sturgeon includes the Great Lakes,
Hudson Bay drainage, Mississippi River basin
and Alabama river systems. While once prolific
throughout its range, sturgeon populations have
declined dramatically since the early 1900s. Causes
for their decline include overfishing, water pollution and habitat loss.
Sturgeons are often called living fossils. Unlike other bony fish, their skeletons
are flexible. Sturgeon are adapted to bottom feeding; they have protractile, tubular
mouths without teeth and a snout equipped with sensory barbels for locating food. The
five rows of bony scutes along the body are very sharp in young fish but become smooth
with age. The most vulnerable stage of a lake sturgeon’s life is between hatching and
development of the sharp body scutes. Like swimming vacuums, sturgeon feed along
the river bottoms, sucking up food items along with bottom debris. The inedible material is not swallowed; rather, it is ejected from the mouth. They feed on a variety of
foods including insect larvae, mollusks, crayfish, fish, worms and algae. Sturgeon
raised in fish hatcheries are fed chopped earthworms, frozen plankton and live brine
shrimp. Sturgeon are widely sought after for their eggs, the source of caviar, but their
flesh is also edible.
Sturgeons grow extremely slowly and live to be much older than most other
North American freshwater fish. They are thought to live an average of 80-100 years.
Growth is influenced by water temperature and food availability. Sexual maturity is not
reached until 15-25 years in females and males at 8-20 years. Spawning cycles only
occur every 4-6 years, resulting in low population growth of the species. Spawning
occurs in the late spring or early summer in shallow, flowing water. Females may scatter as many as 500,000 eggs over the spawning area in short bursts as the males release sperm. The eggs adhere to the bottom substrate and the young feed off their yolk
sac for up to three weeks.
Today the lake sturgeon is listed by most states as threatened or endangered.
The lake sturgeon is also protected from international trade under the Convention on
International Trade in Endangered Species. Many states are involved in some type of
population augmentation program, either through fisheries management, habitat
improvements or reintroduction programs. The Missouri Department of Conservation,
Wisconsin Department of Natural Resources and New York Department of Environmental Conservation along with the US Fish and Wildlife Service are working cooperatively
on sturgeon conservation. The Wisconsin DNR has released approximately 30,000 lake
sturgeon in the Wolf River since 1994. The New York DEC released lake sturgeon into
the Oswegatchie and St. Lawrence Rivers in 1997, and the Missouri DOC has been
stocking juveniles in the Missouri and Mississippi Rivers since 1984.
Lake sturgeon are listed as endangered by the Tennessee Wildlife Resources
Agency (TWRA). The decline of the lake sturgeon in Tennessee is likely due to overfishing and habitat destruction. The French Broad River, the headwaters of the Tennessee
River near the area of Douglas Dam, has been a focus area to improve water quality
through TVA’s Reservoir Release Improvement/Lake Improvement Plan. Due to the
improvements in this area, it is now considered to be an area suitable for lake sturgeon
reintroduction. The Tennessee Aquarium is involved with a variety of resource agencies
and private conservation groups to propagate and release this species into the French
Broad River. Currently, the partnership has released over 6,000 sturgeon into this river
system since 2000. The restoration effort is a long-term commitment and will likely
require over 20 years of active reintroduction and habitat improvements.
The Tennessee Aquarium offers the public an unparalleled opportunity to
encounter this unique creature. Allowing the public to see and feel this living fossil and
learn about its plight will increase public awareness of our region’s imperiled fauna.
Hopefully, together we can bring back this fish to our rivers and continue to improve the
habitat for other aquatic animals.
Sturgeon Encounter Introduction
Welcome to the Sturgeon Encounter. If you wish to touch a sturgeon, please use
two fingers and touch gently on their back. Please do not restrain the fish by grabbing,
lifting or pulling on them. Sturgeon do not have scales and feel much like sandpaper.
The bony plates along their body serve to protect them and can be sharp. The sturgeon
won’t bite you; their mouths are used to slurp up food. Sturgeon grow to be about 5-7
feet in length and can weigh over 100 pounds. Most of these sturgeon are 4-6 years old
and weigh about 10-12 pounds. These animals were raised by the Aquarium. Due to
habitat changes, pollution and overfishing, sturgeon populations have dramatically
declined. The videos above your head will give you more information about sturgeon
conservation. Thank you for visiting the sturgeon encounter. (If it’s really crowded)
Please be aware of other guests who wish to share in this opportunity.
Docents, please be sure to read the Guidelines for interpreting this exhibit.
History of the Sturgeon Population
Information from Sturgeon For Tomorrow Conservation Group, Black Lake, Michigan.
Late 1800s
Lake sturgeon were once perceived as a nuisance fish because they became entangled
in fishing nets and destroyed them, leading to their wide-spread slaughter. As they
became important economically, a commercial fishery grew by the mid- to late-1800s.
For example, the United States led the production of caviar with 60,000 pounds of
sturgeon harvested from Lake Michigan. The commercial catch of lake sturgeon from
all the Great Lakes averaged 4 million pounds. In 1885, 8.6 million pounds were harvested, of which 5.2 million pounds came from Lake Erie.
1910
Lake sturgeon populations declined dramatically and caviar production was shut down.
1929
Lake Michigan closed its commercial harvest after the catch declined to 2000 pounds
compared to 3.8 million pounds harvested in 1879.
Late 1900s
Nearly 80% of the lake sturgeon had been removed from Lake Erie. Several factors led
to the decline of lake sturgeon populations including commercial overexploitation,
habitat loss and degradation by damming of tributaries, preventing access to historical
spawning grounds. Spawning areas were destroyed by siltation from agricultural practices, dredging and pollution.
1987 to Present
As a result of the population decline, lake sturgeon are listed federally as a species of
concern, recognized by the American Fisheries Society as threatened in North
America, and listed as Endangered, Threatened, or Special Concern in 19 of 20 states
throughout its range. The fish are protected in Canadian waters of the Great Lakes
with closed seasons, size limits and gear restrictions.
Recently, interest in the restoration of lake sturgeon has increased greatly. The fish
can serve as an indicator of ecosystem health and biodiversity, particularly because of
its unique life history characteristics.
The Great Lakes area has developed partnerships
between agencies and commercial fishers who report
by-caught lake sturgeon to their respective management agency. Some partnerships allow temporary
possession so critical information can be collected from
the specimens. Since 1994, a sighting survey has been
distributed to anglers and SCUBA divers to report
their encounters.