Fishes, Reptiles, and Amphibians
ENVIRON 311/EEB 320
Winter 2007
Fishes
Lepisosteus osseus: Longnose gar
Fish Anatomy
Fish Anatomy
• Heterocercal tail
– Bony supports extend
through top of caudal fin
– Caudal fin asymmetrical
• Homocercal tail
– Caudal fin symmetrical
– No extension of spine
through top of caudal fin
Family Petromyzontidae
• Lampreys
• Lack jaws, as well as paired
fins, scales, and gill covers
• Body is elongate
• Has unique larval stage,
called the ammocoete stage
– These lack fully functional
eyes and mouthparts; feed
on detritus and drift
• Adults may be parasites,
predators or non-feeders
– Parasitic kinds use teeth on
sucking disk to rasp feeding
holes in fish
Then…
Add some jaws, paired fins, and opercula
(gill covers)…
Family Lepisosteidae
• Gars
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Long, thin body with heterocercal tail
Ganoid scales are armorlike
Long, fixed jaws and sharp teeth
Can breathe air directly
Usually an ambush predator
Prefers large bodies of water, esp. where weedy areas exist
Family Amiidae
• Bowfin or
Dogfish
• Another very
primitive fish
with a heterocercal tail and
the ability to
breathe air
• However, upper jaw (maxilla) is now more mobile
• Often confused w/ snakehead, an invasive species
– Bowfin has a shorter anal fin, heterocercal tail, and a gular plate (hard
plate on throat)
• A large, powerful ambush predator—occupies mainly weedy spots
Family Amiidae
Now…
Turn the primitive heterocercal tail into a
homocercal tail and…
Family Salmonidae
• Trout, Salmon, and
Ciscoes
• Single soft dorsal fin with fleshy
adipose fin and small scales
• Medium to large freshwater
fishes—very important to sport
and commercial anglers
• High O2 demand—needs cold
water (e.g. ground-water streams
and deep oligotrophic lakes)
• Most are predatory, first on
invertebrates and then on other
fish
• Some are migratory
Family Umbridae
• Mudminnows
• Soft dorsal fin placed far
back on body
• Rounded caudal fin
• Small, hardy fish with ability
to survive under low DO;
found in a wide variety of
habitats
• Preys mainly on
invertebrates
• Very closely related to pikes,
which it resembles
Family Esocidae
• Pikes and pickerels
• Soft dorsal fin place far back
on body, roughly even with
anal fin
• Caudal fin is slightly forked
• Snout is duck-billed in
appearance
• Voracious ambush predators
of streams, lakes, and many
wetlands
– Feed primarily on other fish,
including their own kind
Family Cyprinidae
• Minnows
• Simple looking with single
soft dorsal fin
• Mouth ranges from
subterminal to upturned
• Usually without complex
patterning but occasionally
colorful
• Very large and diverse family
• Includes shiners, carps, and
goldfish (the latter two are
invasive exotics)
• Wide variety of feeding
strategies—some are filter
feeders, others predators
Asian Carp…getting closer
• bighead and silver
• imported by catfish
farmers to remove algae
and suspended matter
out of their ponds
• Jump out of water and
can injure boaters
• Separated from Lake MI
by an electric barrier
www.epa.gov
Family Catostomidae
• Suckers and
redhorses
• Look like cyprinids but have
ventral mouth (suckerlike)
with thick lips
• Redhorses may be colorful
and grow quite large
• Benthic—sift through
sediments for invertebrates
and sometimes algae
Family Ictaluridae
• Catfishes
• Barbels, adipose fin and
single spines in both the
pectoral and dorsal fin
characterize family
• Are without scales
• Many are benthic
• Size ranges from tiny to
enormous
• Extra taste buds on body
allow catfish to locate food
where light levels are low
Then…
• Add spines to dorsal and anal fin
• Bring the pelvic fins closer to the
pectoral fins
Family Percidae
• Perches, darters, and
walleyes
• Two dorsal fins: one spiny
and one soft
• Anal fin with 1-2 spines
• Opercular spines
• Darters are generally small
and are primarily benthic
• Others are good swimmers,
voracious predators (first of
inverts, then fish) and
medium-sized
Family Centrarchidae
• Sunfishes and
tropical basses
• Two dorsal fins, usually
connected
• Anal fin with 3 or more
spines
• Includes many sport
fishes
• Small to medium
predators of inverts and
other fish
Family Cottidae
• Sculpins
• Two dorsal fins
• Tend to be dorso-ventrally
flattened, with large head
and dorsal eyes
• Possess pre-opercular
spines
• Prefer cool to cold water—
often associated with (and
eaten by) trout
• Prey mainly on inverts
Family Gasterosteidae
• Sticklebacks
• Easily identified by
spiny “finlets” on first
dorsal fin
• Caudal peduncle
extremely thin
• No scales
• Found mainly in quieter
waters—consume
invertebrates
Reptiles and Amphibians
Class Amphibia
• Amphibians
• Name implies two life
stages: larval and adult
• Many live in or near water for
much of their life cycle
• Respiration may be
accomplished through lungs,
gills or simple diffusion
through the skin, depending
on species and life stage
• Skin is generally moist, not
covered with scales
• Generally sensitive to human
impacts on water quality
Order Caudata
• Salamanders
• Two to four legs and a long
tail—no claws
• Two-thirds of world’s species
live in Americas
• Some species retain larval
characteristics throughout
life (e.g. external gills)
• Some species estivate
during periods of drought,
Order Anura
• Frogs and Toads
• Most have a familiar tadpole
larval stage that develops in
water
– Larval stage may last
anywhere from a few weeks
to a couple of years
– Feeds on algae, detritus,
inverts
• Adult stage has four legs
and is typically terrestrial or
semi-aquatic
– Feeds mainly on
invertebrates
– Some may eat other frogs
or snakes
Family Bufonidae
Bufo americanus
• American toad
• Warty skin and short legs for
hopping (characteristic of
toads)
• Adult occupies all kinds of
terrestrial habitats, returns to
water (often ephemeral) to
breed
• Tadpole is dark, has rounded
tail with little pigment around
the edges
Family Hylidae
• Treefrogs
• Slender, long limbs
and digits
• Usually small
• May be somewhat
arboreal
Family Hylidae
Hyla versicolor/chrysocelis
• Gray treefrog
• Has adhesive pads on
long toes, adapted to
climbing
• Adults warty with bright
coloration under legs
• Usually stay close to
swampy areas
• Tadpoles strongly
patterned—may also be
tinged with color
Family Hylidae
Pseudacris crucifer
• Spring peeper
• Very tiny—more likely to
be heard than seen
– If seen, can be identified
by ‘x’ on back
• Adults are somewhat
arboreal, preferring
swampy areas
• Tadpoles tiny, with
lightly mottled tails
Family Ranidae
• True frogs
• Skin fairly smooth
with well-developed
legs for leaping
• Front toes lack
adhesive pads and
webbing; rear toes
are webbed
Family Ranidae
Rana catesbeiana
• Bullfrog
• Adults are large, with no
dorsolateral ridges and
usually little patterning
on body
• Voice is deep croak
• Spend much of life in or
very close to water
• Tadpoles are large; may
take two seasons to
mature
Family Ranidae
Rana pipiens
• Leopard frog
• Adult has dorsolateral
ridges and dark, round
spots on back
• Voice is snore-like
• Found in wide variety of
wetlands; sometimes
wanders into dry
meadows
• Tadpole mottled
throughout
Family Ranidae
Rana sylvatica
• Wood frog
• Adult easily identified by
dark mask across face
• Voice sounds like clucking
• Prefers wooded
bottomlands
• Usually breeds early;
sometimes before ice is off
of lakes
• Tadpole develops quickly;
has high, relatively
unmarked dorsal fin
Class Reptilia
• Reptiles
• Have scales (few
exceptions) and
clawed toes (if they
have toes)
• Young resemble
adults
Order Squamata
Suborder Serpentes
• Family Colubridae:
Water snakes
• Nerodia sipedon
sipedon, the northern
water snake is only
member in MI
• Is not venomous, but is
persecuted by many
because of this
perception
• Common in/near rivers,
swamps, bogs, etc.
Order Testudines
• Turtles
• Characterized by
carapace and four
clawed legs
• Underbelly called
plastron—may be
variously jointed
• Some are exclusively
aquatic—others are
terrestrial
Family Chelydridae
Chelydra serpentina
• Snapping turtle
• Large, heavily armored
turtle
• Three-keeled carapace
• Spends much of time
submerged—rarely
basks
• In water, eats almost
anything
• Out of water, will try to
bite almost anything,
even cars
Family Emydidae
Graptemys geographica
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Map turtle
Single keel on carapace
Yellow spot behind eye
“Map” pattern on
dorsum
• Prefers large bodies of
water
• Good swimmer—will
eat fish—but also likes
to bask on logs
Family Emydidae
Chrysemys picta marginata
• Midland painted turtle
• Carapace shallow keel
(in females)
• Marked with reds and
oranges on sides and
plastron
• Prefers shallow, weedy
spots
• Omnivorous
Family Trionychidae
Apolone spinifera spinifera
• Eastern spiny
softshell
• Carapace is soft and
pliable—has chocolate-chip
pattern
• Head is small with long
snout for snorkeling
• Mainly a turtle of large rivers
– Spends lots of time
swimming
– Sometimes basks on logs or
rocks, but always where
water is close by
• Largely predatory on fish
and inverts
The End