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• 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

• 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

• Bowfin or Dogfish

• Another very primitive fish with a hetero-cercal tail and the ability to breathe air

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 BufonidaeBufo 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 HylidaeHyla 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 HylidaePseudacris 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 RanidaeRana 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 RanidaeRana 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 RanidaeRana 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 SquamataSuborder 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 ChelydridaeChelydra 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 EmydidaeGraptemys geographica

• 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 EmydidaeChrysemys 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 TrionychidaeApolone 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