module 3
reptiles
INTRODUCTION
Evolution



Carboniferous period (~325mya)  receding oceans/  land plants/  insects
Amphibians evolved to fill new environmental niches + escape from  water
resources
Reptiles evolved from Amphibians
 1st true terrestrial vertebrates
 First amniotes (shelled eggs)  didn’t float away,  predators +  reliance on water
ADVANTAGES OVER AMPHIBIANS
 Internal fertilisation
 Stronger limbs
 Impermeable skin
 Shelled eggs
EVOLVED 2 MAIN LINEAGES
 Lepidosaurs= scaly lizards  modern day tuataras, snakes + lizards
 Archosaurs= ancient lizards (incl. dinosaurs)  modern day crocs + birds
Skulls
TEMPORAL FENESTRAE
 Temporal fenestrae= holes in skull  allows better jaw muscle attachment +
potentially  skull weight for life on land
 Diapsid= 2 temporal fenestrae  most reptiles (except turtles= anapsids)
 Synapsid= 1 temporal fenestrae  mammals
 Anapsid= no temporal fenestrae  amphibians
Classification  4 main groups= Testudines (turtles), crocodilians, tuatara + squamates
(lizards/snakes)
 Debate re. classification
ORDERS/ SUB-CLASSES
 Crocodilia= crocodiles + aligators
 Lepidosauria= squamates
 Rhynchocephalia= tuataras
 Testudines= turtles + tortoises
Global
 Every continent
distribution
 Hotspots= Australia, SE Asia, west + south Africa, South America
 Lizards= highest in Australia
 Snakes= Highest in Sth America + SE Asia
 Crocodilia= Nth Australia, SE Asia + Sth America
Basic
 Air-breathing
characteristics  3-chambered heart  except cros= 4 chambers
 Bony skeleton
 Skin= epidermal plates/scales/scutes
 Ectothermic  don't waste energy on temp regulation
Anatomy +
 Highly variable between + within orders
physiology
THERMOREGULATION
 Body temp reflects ambient/substrate temp
 General preference= >28oC dragons + goannas= 34-38oC
 Cannot perspire
  metabolism, movement, growth + reproduction in non-optimal conditions
 Shuttling heliotherms or basking heliotherms
o Shuttling heliotherms= move b/w sun + shade as temp fluctuates
o Basking heliotherms= stay in one place  e.g. crocs
3-CHAMBERED SEPTATED HEART
 2 atria= right receives deoxygenated blood + left receives
oxygenated blood
 1 partially separated ventricle
 Disadvantages= allows some mixing of O2 + deO2 blood + 
efficient at delivering O2 to body tissues
SKIN- SCALES OR SCUTES
 Scales + scutes both made
of structural alpha + beta
proteins
 Loreal scale= scales b/w
eye + nostril  present in
colubrids/ absent in
elapids





Reproduction
Scales
Formed in the dermis
Overlapping
Help retain moisture
Aid locomotion
Can be shed +
replaced 
removed worn
out skin +
parasites





Scutes
Formed in deep layers of dermis
Individual units
Help retain
moisture
Protection
Some shed +
replace  others
continually produce
keratin at base of
scute
DIGESTION
 GIT= mouth  oesophagus  stomach  Intestines  cloaca
 Carnivores= simple stomach + smaller intestine  protein + fat= easier to digest
 Herbivores= more complex stomach + larger intestine  break down cellulose
 Crocodiles= neurologically controlled heart valve  allows blood to bypass lungs +
go straight to stomach=  gastric juice to allow for very large prey digestion
 Turtles=
o No throat= don't swallow
o Excess water ingested w/ food
o Oesophagus lined w/ papillae (cartilaginous + keratinised projections) pointing
towards stomach to trap food while water expelled
 Snakes=
o elongated oesophagus w/ folds= allow for peristalsis of large prey
o Venomous snakes= 1 pair of salivary glands evolved into poison glands
o Environmental temp determines digestion rate
COMPETITION FOR MATES
 Turtles= head butt opponents + bite copulating males to dislodge them
 Monitor lizards= wrestle competitors
 Dragons= display frills to competing males
 Garter snakes= deposit mucus plug at end of female’s cloaca after mating to
prevent other males
REPRODUCTION
Breeding season  Year round/ multiple seasons/ single annual season
Sexual/asexual
 Mostly sexual
 Some asexual parthenogenesis species
Development
 Most= inside laid egg
 Some= viviparous (live birth)
Clutch size
 1 to >100 eggs
Sex organs
 Male crocs + turtles= penis
 Squamates= hemipenis  only 1 used in single event
Unfavourable
 Some species= Able to delay + stop development in oviduct for
conditions
weeks/months
NESTS + INCUBATION
 Egg incubation= temp dependent  cooler= longer
 Some species= Temp-based sex determination  e.g. turtles (=F) + crocs (=M)
Turtles
Deposit eggs in large burrows + leave
Some squamates Deposit eggs in burrow/ leaf litter + leave
Geckos
Deposit eggs in rock crevices/ under tree bark + leave
Crocodiles
 Nests from vegetation + soil
 Parental care for a few months
DIVERSITY
Crocodilia

Only 2 species in Australia
SALTWATER CROCODILE
Length +
 Male= 4-6m + up to 500kg
weight
 Female= 3-4m + up to 200kg
Habitat
 Saltwater
 Brackish wetlands
 Wet season= swamps + rivers
 Dry season= estuaries + ocean
Colour
 Juveniles= pale yellow
 Adults= greenish/brown
Sexual
 Male= 16yrs
maturity
 Female= 12-14yrs
Food
 Opportunistic carnivores
 Drowns prey + swallows whole
 Mammals/birds/reptiles/fish/sharks
Behaviour
 Social basking
 Fight for territory (esp mammals)
Lepidosauria  5 families
(lizards)
 Higher abundance in arid zones (NT, WA + nth SA)
AGAMIDAE (DRAGON LIZARDS)
 Well-developed front + hind limbs
 Claws on distal digits
 No toe pads
 Lower eyelid= thick, scaly + moveable
 Small scales= granular or spinose (spiny)
 Tongue= broad + fleshy
 E.g. Bearded dragon + frilled neck lizard
GEKKONIDAE (GECKOS)
 Well-developed front + hind limbs
 Claws on distal digits
 Dilated toe pads  climbing + sticking
 Some species have hooks on hindlimbs  climbing
 Lower eyelid= immoveable clear scale covering eye
 Scales= small + granular
 Tongue= broad + fleshy
 E.g. Burrow-plug gecko





FRESHWATER CROCODILE
Male= 2-3m + 70-100kg
Female= max 2.1m + 40kg
Freshwater
Wetlands, billabongs + creeks
Saltwater tolerant

15-20yrs

Birds/ fish/ amphibians/
reptiles/ small-medium
mammals
Shy
Co-exist in small groups


PYGOPODIDAE (PYGOD/FLAP-FOOTED LIZARDS)
 No external traces of forelimbs
 Hindlimbs reduced to small flattened flaps on either side of
vent
 Lower eyelid= immoveable clear scale covering eye
 Scales= large + overlapping
 Scales on ventral surface of body
 Tongue= broad + fleshy
 Long tail relative to body
 External ear
 E.g. Excitable delma
SCINCIDAE (SKINKS)
 Largest Lepidosauria family
 Limbs vary from well-developed to externally absent
 Digits= clawed + no toe pads
 Lower eyelid= vary from thick, scaly + moveable to immoveable
clear scale covering eye
 Scales= large + overlapping  each have core of bone
 Tongue= broad + fleshy
 Some species= ovoviviparous (eggs hatch inside + born live)
 E.g. blue tongued lizards
VARANIDAE (GOANNAS/MONITOR LIZARDS)
 Well-developed front + hind limbs  strong + powerful= run fast
 Distal limbs= clawed + no toe pads
 Some species= large claws  climbing trees + digging
 Lower eyelid= thick, scaly + moveable
 Scales= Granular or spinose
 Tongue= long, slender + forked
 E.g. lace monitor + perentie
Lepidosauria  7 families
(snakes)
 Australia-wide  highest abundance in north + east
TYPHLOPIDAE (BLIND/WORM SNAKES)
 Eyes below thickened scales= black spots only
 No external traces of limbs
 Ventral scales= no larger than adjacent scales
 Tail= short, thick + blunt w/ thorn-like terminal scale (no
tapering)
 Smooth scales  allow ease of burrowing
PYTHONIDAE (PYTHONS)
 Obvious eyes
 Pair of small spur-like vestigial hindlimbs on either side of vent
 Ventral body scales= single row + distinctly wider than other
scales
 Tapered tail
 Head scales= large symmetrical plates or small irregular scales
 Non-venomous
 Some arboreal= prehensile tail
 E.g. carpet python
ACROCHORDIDAE (FILE SNAKES)
 Aquatic  freshwater/estuarine
 Obvious eyes
 No external traces of limbs
 Scales= small + granular
 Tapered tail
 Non-venomous
 Loose, baggy skin  allows it to grip prey
 Highly developed scale sensilla= head scales sensitive to movement
Testudines
COLUBRIDAE (COLUBRID SNAKES)
 Obvious eyes
 Coloured
 Loreal scales present
 No traces of limbs
 Ventral scales= single row + much larger than other scales
 Head scales= large symmetrical plates
 Enlarged teeth in some species
 Tapered tail
 Venomous/ non-venomous
 E.g. green tree snake
ELAPIDAE (ELAPID SNAKES)
 Obvious eyes
 No traces of limbs
 No loreal scales
 Ventral body scales= single row + much larger than other scales
 Head scales= large symmetrical plates
 Fangs at front of mouth for venom injection
 Tapered tail
 E.g. red bellied black snake/ eastern brown snake/ southern death
adder
HYDROPHIIDAE (SEA SNAKES)
 Marine
 Obvious eyes
 No traces of limbs
 Ventral body scales= variable size
 Head scales= large symmetrical plates
 Fangs + venom
 Viviparous (live birth)
 Laterally-compressed tail= paddle-like  propulsion in water
 E.g. yellowbelly sea snake
LATICAUDIDAE (SEA KRAITS)
 Marine
 Obvious eyes
 No traces of limbs
 Ventral body scales= single row + much larger than other scales
 Head scales= large symmetrical plates
 Fangs + venom
 Laterally-compressed tail= paddle-like  propulsion in water
 Oviparous= leave water + lay eggs on land
 E.g. banded sea krait
 4 families
 Carapace= top shell  diagnostic of species
 Plastron= bottom shell
CHELIDAE (SNAKE-NECKED TURTLES)
 Freshwater
 Side-neck orientation= head drawn under shell in horizontal S-bend  b/c limited space
 Distinct ankle joints
 Distal limbs= 4-5 claws + webbing
 Basking heliotherms  either on land or water surface
 Oviparous
 E.g. Eastern snake-necked turtle
CARETTOCHELYDIDAE (PITTED-SHELLED/ PIG-NOSED TURTLE)
 Northern Aus + PNG
 Freshwater  streams/ rivers/ lagoons
 Distal limbs= flippers like sea turtles w/ 2 claws
 Nose= pig-like
 Omnivorous
 Oviparous= eggs laid on river bank in dry season  don’t hatch till conditions good= 
survival rate
CHELONIIDAE (SEA TURTLES)
 Northern Australia
 Body= flat, streamlined + rounded
 Large front flippers
 Cannot retract head into shell
 Carapace= distinct + mostly bone  pattern + scute number differentiate species
 Oviparous  2 clutches per season
 Temp-dependent sex determination   temp=  females
 Late maturation
 Copulate at sea + females migrate to annual breeding site to lay (where she hatched)
 High hatchling + juvenile mortality
Vulnerable
 Carnivorous  benthic invertebrates (e.g. jellyfish)
Loggerhead
 Carapace= Irregular shape w/ 5-6 costal scutes
 Carnivorous  soft invertebrates
Flatback
 Carapace= upturned edges + 4 costal scutes
Endangered
 Herbivorous  algae/ seagrass/ mangroves
Green
 Carapace= 4 costal scutes + dark pigmentation
 Carnivorous  soft invertebrates
Olive ridley
 Carapace= wide + rounded w/ 6+ costal scutes
Critically
 Omnivorous  algae/ coral/ sea cucumber/ jellyfish
Hawksbill
endangered
 Carapace= oval w/ 4 costal scutes
DERMATOCHELYIDAE (LEATHERBACK TURTLE)
 Marine
 Largest marine turtle
 Diet= jellyfish + soft invertebrates
 Carapace= no scutes  leathery skin w/ osteoderms (bony deposits) to support
 7 ridges down back
 Limbs= flippers w/ no claws
 Oviparous= lay eggs above high tide mark in dug out nests  up to 9 clutches per year
ADAPTATIONS
Habitat
Climbing/
gripping
Swimming






Wide diversity= occur in most habitats across Australia
Claws on distal forelimbs  e.g. goannas
Pads on distal hindlimbs w/ hooks  e.g. geckoes
Prehensile tail in some snakes= adapted for gripping  e.g. tree pythons
Laterally-compressed paddle-like tails= propulsion + steering  e.g. sea snakes + kraits
Powerful tails for propulsion  e.g. crocodiles
Desert
climate



Large flippers  sea turtles + leatherback turtles
Webbed feet  freshwater turtles
Metachromatism= adjust body/skin colour in response to temp to assist
thermoregulation  light during high heat + darker in cooler periods
Nocturnal activity= avoid highest heat
Fringed feet= spiny scales resembling fringes  keep traction on sand
Fringed ears= prevent sand entering ears while digging burrows
Burrows=  predation + protect from high heat
Absorb water through feet from moist sand  prevent dehydration
Excretion of nitrogenous waste as uric acid= minimise water loss






THREATS


Habitat loss 
+ destruction 
IUCN status
2 extinct
7 critically endangered + 77 endangered
 human pop=  demand for housing + food=  encroachment on habitats
Land degradation/ urbanisation/  aquatic habitats/  transitional habitats/ 
terrestrial habitats
Change ecosystems
Predation/ native species naivety/ resource competition
Contaminants + pollutants  metals/ herbicides/ pesticides/ PCBs/ endocrine
disrupters
o Bioaccumulation
o Disrupt reproduction
Plastic= slow degradation/ leach chemicals/ ingested + block digestion
Upper respiratory tract disease caused by bacterium
Shell disease in turtles
Fibropapillomas virus= growths lead to vision, movement + feeding loss in Green
turtles
Snake fungal disease= skin lesions + blisters
Novel diseases  e.g. Bellinger river snapping turtle
Collection for food  e.g. turtle eggs dug up + consumed
Illegal pet trade
Harvesting for research
Poaching for skin/shells
Traded for medicinal purposes  snakes, turtles, crocodiles + lizards
Once adult pops exhausted, juveniles taken next=  breeding potential in next gen.
 atmospheric CO2 from fossil fuels=  greenhouse gases=  heat
 ocean acidification
 coral bleaching   turtle food
 drought + bushfires  cant escape
Temp-dependent sex determined species= skewed sex ratios w/  temps
Invasive

species

Environmental 
pollution
Disease +
parasitism






Unsustainable 
use





Climate

change




CASE STUDY: BELLINGER RIVER
SNAPPING TURTLE
Classification 
Species
information +
biology





Order= testudines
Family= chelidae (snake-necked turtles)
Species name= Myuchelys georgesi
Endemic to Australia
Habitat= rivers w/ continuous flow, deep pools, clear water + some rock/substrate
Do not like brackish waters
 Highly oxygenated habitat assists cloacal breathing
 Neck tubercles= help detect movement
 Omnivorous  macro-invertebrates, fruit, aquatic vegetation
 Hunt w/ eyesight
 Winter breeders  Lay oct-nov (10-15 eggs)
Ecology
 57km stretch of Bellingen + Kalang river systems
 Limited range= any impact on area can be catastrophic
 Prior to 2015= pop of >1500  locally abundant
 Face comp from Macquarie river turtle which has been introduced
2015 mortality  14-18 Feb 2015= ~500 dead/dying found
event
 wiped out 95% of all pop in very little time (~6mths)
Initial
 Rapid collection of remaining healthy turtles from site
response
 Collaborative project= many govt + independent organisations involved
 Veterinary care to sick turtles  however  mortality + biosecurity risk= euthanised
PROJECT AIMS
 Rapid protection of turtle
 Disease diagnosis
 Understand ecology of virus
 Assess impact in other species
 Develop diagnostic test + potential vaccination
Disease
 Lethargy + slow movement
symptoms
 Ocular inflammation
 Plaque-like skin lesions
Identifying
 Usual process= Rule out explanations progressively before proceeding using
the cause
clinical/necropsy, histology + diagnostic testing
 High mortality + potential risks= all started immediately
CLINICAL + HISTOLOGICAL SIGNS
 Ruled out environmental causative agent
 Water quality + pollutant testing= all negative
 Necropsy results= indicate pathogen
HISTOLOGY + BACTERIAL TESTING
 Ruled out bacterial causative agent  suspected virus
 All tests came back negative
VIRAL TESTING
 Excluded common viruses  indicates novel virus
 Tested for common viruses= all negative  ranovirus/ adenovirus/ paramyxoviruses/
herpesviruses
Detecting +
STEP 1: ISOLATE VIRUS
understanding 1. Inoculate medium w/ tissue homogenate
2. Incubate culture
the virus
3. Remove grown cells
STEP 2: FIND OUT WHAT IT IS
1. Isolate viral nucleic acids
2. Nucleic acid sequencing  does it match another virus?
3. Phylogenetic analysis  most related to viruses in family Coronaviridae
4. Named Bellinger river virus
STEP 3: DESIGN A DIAGNOSTIC TEST
 PCR using primers to detect + amplify specific sections of the nucleic acid sequence
STEP 4: TEST ON TARGET AND OTHER SPECIES
 Only detected in Bellinger River Snapping Turtle
 2 cases in Murray River turtle= may have been false positives
Conclusions
 Novel virus is pathogenic cause of mortality event
from research  Other factors likely contributed  e.g. environment impacts on immune system
 High water temps in river= good for viral growth
 Off-site conservation  outside natural habitat
Ex-situ
management
REASONS FOR EX-SITU MANAGEMENT
 Insurance colonies  quick mortality= important to remove healthy turtles
immediately
 Provide animals for reintroduction high mortality= important to breed some for
after disease understood
 Conservation research  many unknowns= need to understand as much as possible
CONSIDERATIONS
 Species prioritisation
 Analogue species  use similar species to develop appropriate husbandry protocols
 Founder collection  genetic diversity
 Biosecurity  careful hygiene, PPE, quarantine
 Resource availability  funding + staff
INSURANCE POPULATION
 16 individuals collected from upstream areas of river
 Quarantine at WSUni until tested for virus  protect each other + other species
 Early 2016= Transferred to Taronga
 DNA tested to ensure wide genetic background
 Jan 2017= first breeding season  4 clutches from 4 females= 22 eggs hatched
 2018= 31 eggs hatched
 Artificially incubate eggs= higher chance of success  wild= 70-80% survival rate
 Raised in mesocosms= mimics natural environment under controlled conditions
 Fed pet turtle cubes= contain all essential nutrients  couldn't be fed natural diets
b/c unknown whether disease caused by food/environment
REINTRODUCTION
 Nov 2018= 10 captive-bred turtles released to upper Bellinger river
 Only release juveniles
 Health assessment prior to release
 Radio transmitters attached to shell tracking survival + monitoring
 9 still alive 6 months later