reptiles Flashcards
ectothermic
environment regulates body temp
preferred optimum temperature zone
range of temperatures required to allow thermoregulation
preferred body temperature
optimum temp for body functions
behavioural fever
seek out higher than normal temperatures when sick/stressed
humidity
50-70%
lighting
12-14 hours of light/day
UVA light = 320-400nm - stimulates reproductive behaviour in lizards
UVB - 290-320nm = required for conversion of vit D3 in skin, important for calcium metabolism
diet
Ca:P = 2:1
feeding frequency depends on weight gain/condition
basic features
vertebrates
heavily keratinised skin
ectothermic
internal fertilization (most egg laying)
nucleated red blood cells
what is thermoregulation controlled by
hypothalamus
2 main mechanisms of acquiring heat
heliothermy - sun
thigomothermy - warm object
CV system thermoregulation
heart rate and vasodilation/vasoconstriction
high temp - HR and vasodilation increases - warm blood to periphery
low temp - HR and vasodilation = warm blood retained in core
lungs can be bypassed by means of a right to left shunt, meaning reduced heat loss by evaporation
behavioural thermoregulation
body position and shape
burrowing/hiding/shade seeking
pigmentation
metabolism
slower than in mammals
15-20% at 37 degrees
dependent on activity, diet, size, body temp
reptiles utilise mainly aerobic metabolism but will switch to anaerobic for periods of intense activity
consequence = build up of lactic acid, drop in blood pH and reduced affinity for oxygen in haemoglobin
light dependency
for physiological functions
natural sunlight provides optimum full spectrum
UVA 320-400nm required for normal feeding behaviour, reproductive activity etc
UVB 290-320nm required for conversion of sunlight to vitamin D3
skeleton features
flexible spine
number of vertebrae variable
ribs well developed
movement of head occurs mainly at occipital condyle
99% of calcium stored in bones
what conditions can develop if calcium metabolism is altered or dietary supply is insufficient?
metabolic bone disease
hypoglycaemia
bone features
lack the haversian bone systems
bone healing is slow
skeletal growth
epiphyseal growth plates do not close - no skeletal maturity occurs
skull features
2 skull types; diapsid and anapsid
integument features
waterproof
shed periodically to allow growth
3 layers;
stratum corneum
intermediate layer
stratum germinativum (stratum basale)
ecdysis
shedding of old skin
controlled by thyroid gland
dysedysis
failure to shed
usually husbandry related
CV system features
blood volume = 8-10% bw
3 chambered heart
mixing of oxygenated and deoxygenated blood occurs but kept to a minimum
portal systems
- renal portal system
external iliac veins - carry blood draining from hind limbs = enter large renal portal vein
means some of blood returning from hindlimbs enters kidney before returning to circulation - hepatic portal system
respiratory system
larynx easily identifiable
trachea leads to paired lungs
no diaphragm
lung is simple sac structure - reticular pattern of ridges increases surface area for gas exchange
phases to respiration
expiration
inhalation
rest phase
temperature controlling factor
GI system
oral cavity - mucous secreting glands - moisten and lubricated food
teeth - only present in lizards and snakes
dentition
enamel, dentine and cement - NO periodontal ligament
3 types of tooth:
- acrodont
-pleurodont
-thecodont
polyphydonty
teeth continually replaced throughout life
urinary system
excrete uric acid as the end product of protein catabolism
kidneys located in caudal coelomic cavity
no renal pelvis, no loop of henle, no renal pyramids
bladder present - except snaked
ureters open directly into cloaca
egg laying types
oviparous
lay eggs which develop outside of body
viviaparous - eggs hatched internally
which feature determines the sub-order a species is placed in?
anatomy of neck
what are shells composed of
keratinised plates called scutes
chelonia cardiorespiratory
nasal breathers
trachea short
no diaphragm
can switch to anaerobic respiration for long periods.
3 chambered heart + renal portal system
chelonia blood sampling
jugular vein
dorsal coccygeal vein
chelonoa GI
25% species completely herbivorous, rest omnivorous
no teeth, sharp beak instead
thick fleshy tongue
simple stomach, lies near bilobed liver
colon large and caecum distinct in herbivores
digestion slow = 2-4wks transmit time
chelonia - urinary system
kidney has no loop of henle and no renal pelvis
urine can be excreted directly into urodeum or refluxed into either bladder or colon for further water conservation
chelonia male reproductive system
single phallus which protrudes from the proctodeum =not involved in urination
concave plastron to assist with mounting
presence of phallus
longer distance from caudal edge of plastron to cloaca
longer broader tails than females
internal testes
chelonia female reproductive tract
paired ovaries and oviducts
ova travel down reproductive tract and egg is formed
oviparous
females store sperm for a long time - up to 6 years
flat pastron, shorter distance between caudal carapace and cloaca
lizards thermoregulation
colour change
body posture/position
behaviour
lizards integument
integument heavily keratinised
skin waterproof
some species - spines/horns
skin heals slowly in reptiles
ecdysis occurs at regular intervals
lizards skeleton
kinetic skill - allows wider gape
- pterygoideus and external adductor muscles main jaw closers + depressor mandible is main jaw opener
flexible spine
cardiorespiratory lizards
large volume lungs
glottis closed except during inspiration and expiration
no diaphragm
rely on respiratory muscles - increase chance of lung infection
the 3 lung types found in lizards
unicameral
paucicameral
multicameral
lizards GI
omnivores and insectivores - GI tract short and simple
herbivores - hindgut fermenters
urinary system lizards
lobulated kidneys
bladder
species with high potassium diets have salt glands which are additional route for excretion
male reproductive system
abdominal testes
paired hemipenes
- stored in tail base
- only one used in each copulatory event
- not used in urination, often prolapse
reproductive tract female lizards
paired ovaries and oviducts = long and pleated
mature oocytes that fail to ovulate remain in ovary
sexing lizards
males =
larger, more colourful
presence of prominent dewlaps, crests and spines
have prominent femoral pores on thigh areas
snakes thermoregulation
based on behaviour
basking used to gain heat, coiling to retain
snake integument
scales joined by small folded areas of skin
pigment in subdermal layers
ecdysis important to allow growth
