Reptiles 2 Flashcards
Chelonia order
chelonia/testudines
Shell is characteristic to chelonia
Chelonia sub orders
Only good to know for ease of handling!
a. Pleurodira – snake/ side neck
i. Can bend their neck at 3 points horizontally
ii. Can retract head but it neve goes furrly in shell
iii. Makes more flexible so more able to bite
b. Crytodira
i. Flex neck at 2 points vertically
ii. Can retract head right back fully into shell
Temp control
- heliothermic = gain heat by basking in sun
- shell can hamper cooling
- Subtropical and temperate species will hibernate in response to decreasing temperature
Chelonia shell nerves? and shedding
- Keratin overlines bony plates
Layer of epidermis over bone nerve and blood supply. Any damage the tortoise will feel it AND bleed - in the terrestrial tortoise scutes are not shed – just more keratin laid down from base
- In some turtles scutes are shed or peel away to make room for new scutes
NAming aprts of the chelonia shell
- Dorsal domed part = carapace
- Ventral flattened part = plastron (males more concave to females)
- Scutes overlie dermal bone plates
Talk ribs and vertebrae, pleuras
- ribs fused with bony plate
- 5 vertebrae, names after the body part that is adjacent to it
- 4 pleuras where expect lungs
- 12 marginals at the side
How is the shell useful for a vet?
- Shell gives lot of information on health
- Will see changes in scute shape and date if diet, UV light etc is inadequate
- Useful to see if any abnormalities
Shell oldest and newest
oldest part on top
Chelonia skeleton, modifications
- Limbs project laterally
- spine and ribs fused
- Pectoral and Pelvic girdle are vertical within rib cage!
• Scapular forms sort of buttress for shell, giving strength
• Modified pectoral girdle that is fused like birds with acromian process that sticks out front
• Pelvis vertical within rib cage and gives shell shape
• Spine and ribcage fused and overlain by bony plates
Chelonia cardiorespiratory
- Nasal breathers
- Trachea short and bifurcates quite early on
- NO diaphragm - there is a sheet of tissue that separates abdominal cavity from lungs but it has no functional use
- Lungs lie dorsally under carapace
Structure of the trachea means what
- STRUCTURE: short and bifurcates quite early on
- Shortness allow to breath in unhampered manor even when neck withdrawn – trachea remains straight even when got a kink in the neck
- Reptiles easy to intubate but tortoise are actually really tricky as glottis is closed until takes breath! – short tube needed so don’t go down a bronchi!
Significance of no diaphragm in chelonia
No cough reflex therefore so much more susceptible to respiratory disease
Movement of limbs and head help to alter internal pressure within the body and assist respiration
No real separation, just a membrane so more prone to respiratory disease and no coughing reflex
Lungs and chelonia
- Lungs lie dorsally under carapace
- Aid buoyancy in aquatic species
- Able to breath hold for long periods of time, gaseous anaesthesia won’t work as can breath hold!
Chelonia heart
- chambers
- Other system>
- location
- All (apart from crocs) ahve 3: Left atrium, right atrium, ventricle (separated by muscular rings
- Renal portal system
- Chelonia, heart lies posterior to pectoral girdle
How to auscultate chelonia heart
Shell can make auscultation difficult, 2 options
OPTION 1: Use damp towel round shell and stethoscope on that which reduces the air interface and makes it easier to hear
OPTION 2: Doplar ultrasound to visualise blood flow, place in between neck and forelimb = least hampered view
Make sure Posterior when ultra sound!
How to blood sample chelonia
Jugular vein if can get head out
Dorsal coccygeal vein in tail
Chelonia GI
25% species completely herbivorous
Others omnivorous – prefer slow prey!
No teeth, use sharp keratinous beak instead
Thick fleshy tongue – helps prehend food
Stomach simple, lies near large bilobed liver (lies either side of stomach)
Short small intestine
Colon large in herbivores, and cecum distinct if lots of plant material
Digestion can be slow -2-4 weeks transit time – when hibernating can’t eat 2-4 weeks before otherwise food would rot inside
Chelonia urinary system:
- location of kidneys and appearance
- Excrete
- Kidney located under carapace and lobulated. NO loop of henle and NO renal pelvis
- Excrete wither urea or uric acid
About chelonia urine
Urine hypo or iso tonic to blood.
Urine often very dilute – often have to reabsorb (refluxed into bladder or colon)
Urine can be excreted directly into urodeum, or refluxed into either bladder or colon for further water conservation
Quite prone to forming bladder and cloaqual stones
Chelonia male repro
- Single phallus which protrudes from the proctodeum
Not involved in urination, just mating! - Testes in caudal coelomic cavity, just cranial to kidneys
- Testes Increase in size during breeding season and decrease for rest of time
- As ectothermic, find with having abdominal testes
How to sex
MALES:
- Concave plastron to assist with mounting
- Presence of phallus (although clitoral hyperplasia can look like a phallus – don’t get it wrong)
- Longer distance from caudal edge of plastron to cloaca
- Longer, broader tails than females
What sort of egg layers are chelonia?
Oviparous lay eggs and young nourished by yolk sac
Chelonia and sperm and egg bound
Can store sperm for a very long time – up to 6 years
Flat plastron, shorter distance between caudal carapace and cloaca
Can get egg bounds (ovarian follicular stasis) seen to be husbandry related- e.g. lack of Ca and light
Lizard taxonomy
Kingdom: Animalia Phylum: Chordata Class: Reptilia Suborder: Lacertilian Order: Squamata
LArgest and biggest smallest
- 3 cm chameleon
2. 3.3 m Komodo dragon huge
List the four recognised infraorders
- Iguania = Includes iguanas, anoles, water and bearded dragons, chameleons
- Gekkota = Includes geckos
- Scincomorpha = Includes tegus and skinks (likely to see)
- Varinoidea = Includes Gila monster, komodo dragon, monitor lizards
Colour of lizards depending on time of day
- Change amount of melanin in skin to absorb more or less light
- Happens in absence of anything else – always darker in the day to reduce reflection and maximise heat uptake.
- Regulator is internally, rather than by exposure to light or temeprature
- If in dark box for 24 hrs these changes still happen
- Always darker in day to reduce heat
- Regulated internally rather than exposure to light or temp
How do lizards change body position in resposne to heat
- Flatten body to maximise SA for heat absorption
- Angling towards sun
- Hiding if too hot
Integument of lizards
- Heavily keratinised
- Waterproof but breathable skin
- skin heals v slowly
- Ecdysis occurs at regular intervals and more regularly with rapid growth
- Some species have horns for defence
- some species have skin flaps for courtship
- LEatherback vs silk back (poor protection, welfare concern)
Lizard skull
- kinetic like snakes which allows for wider gape
What are the main jaw closers and openers?
- Pterygoideus and external adductor muscle main jaw closers
- Depressor mandible is main jaw opener
- Jaws can shut like a trap door = v strong shutting mechanism
Lizard Lungs
- Just remember lungs are all simple and sac like, with some variations - unicameral, paucicameral, multicameral
- Large volume lungs
Functional favioli rather than alveoli
Sac like lungs with mechanisms to increase SA for gas exchange
No diaphragm and no membranous separation separating the abdominal cavity from lungs so rely on respiratory muscles for breathing. Increased risk of lung infections as can’t cough
Used for buoyancy, display and vocalisation additionally
Lizard upper resp tract
- Glottis is closed except during inspiration and expiration
Lizard lower resp tract
Like all reptiles – no diaphragm – rely on respiratory muscles for breathing so inc risk of lung infections as can’t cough things up
Rely on respiratory muscles
Increases chance of lung infection
3 lung types found in lizards
Heart lizard
- 3 chambered (like tort!) and renal portal system
What to remember with lizard renal portal system?
potential issues with giving drugs in back half and caudal half of body
Lizard where to venupuncture
- Ventral coccygeal (tail) vein caudal to cloaca bit like blood sampling from cow tail = Best
- Axillary venous plexus (armpit)
- Ventral abdominal vein (fragile and can’t see) - avoid
Lizard GI
- short and simple - omnivores and insectivores
- Herbivorous lizards have a more obvious cloaca and more developed/ longer colon
- Herbi = hindgut fermenters. Need Micro-organisms and high ambient temperature required it
Lizard teeth
- Teeth: acrodont that sit on surface, without socket (chameleon and water dragon)
- Most of the others have pleurodont teeth – sit on medial surface of the bone with eroded lingual aspect
Liz urinary system
- Lobulated kidneys – in caudodorsal celom
- Most species have a bladder
- Urine enters the urodeum (via the ureters)
- Can reflux into bladder or coprodeum for further water absorption - Species with high potassium diets (i.e. herbivores) have salt glands which are an additional route for excretion
- Don’t mistake white powder up nostril for respiratory disease!
Male lizard:
1. location testes
2. type of penis
about
- Testes are abdominal, cranial to kidneys
- Paired hemipenes – just copulation
a. Stored in tail base
b. Only one used in each copulatory event
c. Engorges and protrudes through cloaca when ready to mate - Not used in urination
- Solely an organ of reproduction
a. Will often prolapse
b. Can surgically remove if problematic
Female lizard repro
- Paired ovaries and oviducts (long and pleated)
- Mature oocytes that fail to ovulate can remain in ovary
a. Follicular stasis - Ovulated oocytes may remain in oviduct
a. Egg binding
Types of lizard repro strategies
- Oviparous - eggs laid and young have yolk sac for nutrition
- Viviparous - young develop in egg within repro tract and hatch out before born
- Parthenogenesis - few capable which is live young
Sexing lizards
- tricky!
- Radiography, enoscopy and ultrasound are good!
- Males:
Larger, more colourful, Presence of prominent dewlaps, crest, spines
Prominant femoral pores on thigh area
Cloacal bulge = site of hemipenes - can use probe but less useful than in snakes
- Can evert hemipenes
Snake taxonomy
K: Animalia P: Chordata C: Reptilia O: Squamata Suborder: Serpentes F: 4 families: a) Colubridae – see in practise b) Boidae – see in practise c) Viperidae - venomous d) Elapidae - venomous
Snake thermoregulation:
Ideal temp,
Torpor, death, heat stress
- ideal for most species is between 18-34 degrees
- Torpor at <10⁰C, death occurs at <4⁰C
- Heat stress at >35⁰C, death at 38-44⁰C
- Basking, open up body used to gain heat, inc SA, coiling to retain it
- Hiding in shade to prevent heat gain, uncoiling to lose heat
General integument snake
- Scales, joined by small folded areas of skin – allows to expand when eat MAAASSIVELY!
a. Allows expansion of the integument when eating a large meal! - Pigment in subdermal layer
- Ecdysis important to allow growth
a. Shed entire skin including spectacles (covering of eye)
General anatomy snake: What is located in cranial 1/3
Heart, Trachea, Oesophagus, Thyroid, Proximal Lung (most species left lung is tiny in many species non functional!) whereas right lung takes up most of the body, is elongated
General anatomy snake: What is located in middle 1/3
Stomach, Liver, Lung, Spleen, Pancreas
General anatomy snake: What is located in caudal 1/3
Intestines cranial to kidney, Kidneys, Gonads
Snake skull
- Kinetic Skull
a. No middle ear cavity
b. No mandibular symphysis – allows to open out
c. Loose jaw articulation
d. Independent movement of upper and lower jaws – “walk” over prey
e. Teeth bend backwards!
Snake heart + location
- 3 chambered heart (2 atria, 1 ventricle)
2. Located approx. 1/3rd down the body
Snkae venupuncture
ventral tail vein or cardiac puncture if anaesthetised animal
Snake glottis locaiton. What does this mean
- v rostral, right above tongue
2. MEans it avoids occlusion when swallowing, allowing snake to breath when eating huge
Lungs
- simple sac like lungs
2. Poor cough reflex so suseptible topneumonia
Snake GI
Teeth used for:
Type of teeth
3. Tongue
- Teeth used for prehension of food
a. Don’t chew just swallow! - Pleurodont teeth lingual aspect of bone
a. Maxillary teeth can be modified into fangs, can inject venom into fangs - Tongue lies in sheath below glottis, can protrude through lingual notch without opening mouth
a. Use for touch, taste, olfaction
How does food move through snake body
with assistance from the axial muscles
Not much muscular contraction of GI itself, outside – external muscle pressure
Simple or complex digestive tract? snake
- simple.
2. only some boidae have a cecum
Snake stoamch
role
how quickly do they digest adn does this depend on anything?
cardiac sphincter?
a. Role in food storage (along with oesophagus)
b. Mainly digestion
i. Rapid digestion but absorption poor.
ii. Rate of digestion depends on external temperatures and metabolism and dietary needs of that snake
iii. 5 days for adult rat
c. Poorly developed cardiac sphincter – really prone to regurgitation if really stressing out or handling after meals
Snake liver and gall?
Elongated liver, with gall bladder For fat digestion
Snake kidneys
- Kidneys located in dorsal caudal abdomen
a. Lobular
b. 10-15% of nose to cloacal length - Ureters enter directly into cloaca
a. No bladder
b. Some species have small dilations of - distal ureter
- Males have sexual segment to kidney
a. Secretions form copulatory plug
What age do snakes reach sexual maturity
- 1-5 years (size dependant)
2.
Snake male and female repro
- Males
a. Two intra abdominal testes, cranial to kidneys
b. Paired hemipenes – everted singly during mating - Females
a. Oviparous ( egg laying) or viviparous (live)
b. Two ovaries
i. Some species have lost one
ii. Ability to store sperm for years!
How to sex snakes
- Several ways of sexing
a. Tail base broader in males (due to hemipenes within cloaca)
b. Eversion of hemipenes
c. Probing cloaca – insert probe into cloaca
i. 6-10 scales in males – pocket there for hemipenes
ii. 2-3 scales in females - In addition male boids will have
a. Longer tail than females (count scales)
b. Larger spurs (vestigial remnant of pelvis)
Snake sensory
- Olfaction
- sight
- Hearing
- Thermoreception
- Olfaction most well developed sense
a. Have jacobsens organ (like sheep) in addition to normal olfactory cells
b. Forked tongue picks up scent molecules and delivers them directly into the pits - Sight is poor – due to number of factors
a. Limited movement of eye, reduced ciliary body
b. No nictitating membrane
c. Eyelids fused to form ‘spectacle’ can see movement, foten rely on other things like infra red, thermo, scent - Hearing
a. No external ear, but well developed inner ear
b. Good detection of low frequency sounds only
i. Vibrations picked up by quadrate bone and passed to ear/brain for processing - Thermoreception
a. Infrared sensors, between eye and nostril
b. Allow detection of warm blooded prey in complete darkness
