Herpetology Exam 3

tuatara

found in a few islands off New Zealand

Rynchocephalia

• beaked head

• Sister group to lizards and snakes (squamata) - closest relatives

• Common as fossils, 2 species living

• Looks like a lizard but many primitive characteristics

• primitive amniote skull

• Large, heterodont teeth

• Paired outpockets in posterior wall of cloaca, precursors to hemipenes?

• Eggs laid in burrows, 12-15 month development!

• Long lived animals, >70 years in captivity

• Uses burrows, seabird burrows

• Mostly nocturnal, optimal temp 63-68^oF (likes colder temps)

• Insectivorous, bird nestlings/eggs also

• sort of endangered

Alligators and crocs

•Crocodylians belong to an archosaur lineage that dates back to the late Triassic, extensive fossil record.

•Only ~26 species worldwide, endangered

•Skin, meat, “dangerous”

• heavily armored with osteoderms

osteoderm

bone skin

crocodylians

• Aquatic, Freshwater & some saltwater

  • Nostrils at tip of snout with valves

    • Secondary palate, can breathe with prey in mouth

    • Advanced respiratory system, 4 chambered heart

• oviparous

• Temperature-dependent sex determination

• Social behavior often complex

  • Parental care- build nests and mothers protect, then transport babies to water

  • Vocalizations

  • Body postures, head slapping

  • mating sensory organs on mouth

• Eat anything

  • Often drown larger prey, gulpers not chewers

  • can’t eat huger things, drown it/hide it to rot, then rip apart

• great digestive systems, disolve bones

• “spin move” aka “death roll”

• Around world in tropical, subtropical regions

  • 3 families, ~26 species

  • 2 species in the U.S.

alligatoridae

•2 Alligators and 6 Caiman

• American and chinease alligator (short snout)

•Teeth in lower jaw fit in pits in upper jaw

•Large rivers, swamps, lakes, lagoons

•El lagarto (the lizard in spanish)

Male American alligators can weigh 1,000 pounds (454 kilograms), 11.2 feet (3.4 meters) long. Female alligators are on average 8.2 feet (2.6 meters)

crocodylidae

•2 genera, 13 species

•4^th tooth in lower jaw in notch in upper jaw

•Largest= Saltwater croc, 7m (20’ 2400 #)

alligator vs croc

left alligator, right croc

american croc

central/south america

gharial

2 species, garial and false gharial

•Fish eating crocodile, fish specialists- thin snout=fast

• long pointy teeth

•Endangered, now just in a few rivers in Nepal, northern India, 2% of historic range

•Big (>19 ft), awkward on land, great in water

•Adult males have a distinct boss at the end of the snout, which resembles an earthenware pot known as a ‘ghara’

• could be for vocalization, resonates

•Only crocodilian so sexually dimorphic

caimens

central south america

snake venom

• It is modified saliva

• Complex mix of proteins & enzymes

• Has about 20 different enzymes, of which, a species
  usually has between 6 and 12

• Venom’s primary importance is to immobilize its prey,
  then to help it digest it.

• ~300/3000 species of snakes

venom anatomy

bites to human

• Probably 7000-8000/yr in U.S.

  • 5-6 deaths

• E. & W. Diamondbacks most deaths

• Males 17-27 years old…alcohol

• Mortality rate in developed <1%

• snake worshippers- evil, test their faith

• Around 5.4 million people are bitten by snakes each year

• 81,000-138,000 die each year, lots of disabilities

• neglected tropical disease that disproportionately affect children, rural communities, and crisis-affected populations 

illegitimate vs legitimate bites

legitimate- bit by accident

illegitimate- keep snakes on purpose, get bit

venom

• need to subdue large prey with venom

• cooperative behavior unlikely, can’t share food

• can meter amt of venom, conserve supply - “dry bite”

  • more venom= quicker dies

  • will bite, follow, swallow unconcious animal

aglyphous dentition

• garter, milk, burmese python etc

  • recurve teeth

opistogylphous

rear fangs

• enlarged, grooved rear fangs, need to chew

  • pop toads after enlarged

Proterogylphous

• Anterior fangs deeply grooved or tubular

  • front fangs, not very long

• Elapidae (cobras, etc.), only 11mm in 4m cobra

• Typically seize prey and hang on

solenogylphous

• Can fold backwards, tubular, retractable

• 29mm fangs in 2m Gaboon Viper (3x length of cobra)

• Quickly stab & recoil, toxins in deep

• vipers, rattlesnake

• stab and release

Neurotoxin

have the ability to damage and or destroy nerve tissues

• Cobras and Coral Snakes

  • Ptosis (unable to keep eyes open), lethargic, muscle weakness, paralysis spreads throughout the body causing inability to speak because of difficulty breathing.  Salivation occurs followed by vomiting and frothing around the mouth.

Hemotoxins

affects the blood and causes Hemolysis and Hemorrhage

• Vipers

• western diamodback rattlesnake,

  • Very painful. Inflammation and oozing occur.  Bleeding from the mucous membrane occur at the mouth, anus, and nose and there is hemorrhaging under the skin. 

  • slower and more painful than the neurotoxin.  Finally, there is vascular collapse  and loss of consciousness.

  • swellings, bruising

  • hemo = muscle

Myotoxins

muscle pain and turn urine brown to black because of the protein Myoglobin that is present

• sea snakes

• yellow bellied sea snake

  • There are no symptoms really.  Just severe upper body pain and urine changes to brown black color.

  • myo = blood

antivenim

• antibodies to venom

• inject horses/sheep, suffers immune response

• treat envenomation into others

• “passive immunity”

• expensive

antivenom administration

•Early administration is crucial: The antivenom is most effective when given within 8 hours of the bite. 

•Allergic reactions: As with any antivenom, there is a risk of allergic reactions, so patients should be monitored closely. 

•Other treatments: In addition to antivenom, supportive care, such as intravenous fluids, pain medication, and respiratory support, may be necessary. 

•Not a substitute for prevention: If you are in an area where venomous snakes are present, take precautions to avoid bites.

snakebite management

herpetoculture

The keeping of live reptiles or amphibians in captivity either as a hobby or a commercial breeding operation.

herpetology vs herpetoculture

• Often amateurs

• Different than pet keeping, don’t give names usually

• Emphasis on a few species – artificial selection for certain traits as in domesticated animals

• Can be some tension between groups, concern that collection of wild specimens is harmful

• Released animals in wild a problem – big snakes

• conservation tool, increased reproductive output

• insurance policy against catastrophic events

• learned behaviors in captivity=decreased survival released in wild

breeding challenges

—Inbreeding depression

—High costs

—Ethical considerations- some oppose bringing into captivity

—Perhaps a tool, but not a panacea

complete domestication

significant genetic and behavioral changes through human selection and breeding, making them reliant on humans for survival and reproduction

must be

• docile, not panic, breed well in captivity, social structure easy for human management, useful purpose

  • started domestication = didn’t have to hunter gather, could spend time on war/inventions etc instead of worrying about food

mutations

• Genes controlling color and/or pattern

• Selective breeding

  • Valuable at first... then market gets saturated