Reptiles Flashcards
Explain the difference between hinged tortoises and hinged terrapins
Hinge tortoises have a hinge in the carapace in adults which allows the rear to close and protect the hind feet and tail region
hinge terrapins have a hinge at the front if the plastron that can close and protect the head and front legs
Name the different Chelonian (tortoise) species in south africa
Greater padlooper
Parrot- beaked tortoise
Karoo padlooper
Speckled padlooper
Leopard tortoise
Angulate tortoise
Kalahari tent tortoise
Tent tortoise
Geometric tortoise
Speke’s hinged tortoise
Bell’s hinged tortoise
Lobatse hinged tortoise
Natal hinged tortoise
Name the different terrapin species
Marsh/ helmeted terrapin
Serrated hinged terrapin
Pan hinged terrapin
Okavango hinged terrapin
Mashona hinged terrapin
Yellow bellied hinged terrapin
Name the different turtle species
Leatherback turtle
Green turtle
Hawksbill turtle
Olive Ridley turtle
Loggerhead turtle
Explain reptiles sense of vision in depth
-extremely keen sense of vision similar to mammals and birds
- have a lens, retina and cornea
- due to rods and cones in the eye some species able to see colour
- shape of the pupils: diurnal( round pupils) nocturnal( vertically elliptical)
- some gecko species have a ‘crenelated’ pupil or wavy edge to the pupil, closing pupil during day time and light inly enters through 4 small notches
- crocodiles have a nictitating membrane(same as birds) that is a transparent eyelid used to wipe of dirt from the eye.
- when crocodiles go under water this membrane closes
- eyelids of most snakes, lizards can not move and thus they see through a protective spectacle( fused eyelid over the eye) that is replaced when they shed their skin
- burrowing reptiles do nit have complex eyes but rather eye holes or deep lying eye that only detect light and are extremely light sensitive
- reptile eyes generally on side of head allowing for greater field of vision lacking depth perception
- tree dwelling reptiles have more forward facing eyes, narrow snout and in more extreme cases horizontal elliptical or key whole shaped pupils
- difference in eye placement shows us that eyes on side of the head good for picking up movement when stationary and eyes in top of the head for picking out and identifying stationary prey
Explain the sense of smell in reptiles in depth
-Similar to mammals odours detected in nasal cavity
- vital to reptiles to detect prey,mates, predators
- sense of smell vital to nocturnal, or subterranean reptiles
- most reptiles(not crocodile) have vomeronasal organ called the Jacobson organ in the roof of the mouth that provides animals with sensory info on smells through chemoreception.
- forked tongue in snakes and some lizard species Jacobson organ very directional, can accurately follow sent trails
- further apart tongue tips are held while collecting sent particles, the better the ability to follow scent trail
- this is possible due to the fact that the tongue is forked, each tongue tip supplies smell particles to the respective lobe of Jacobson organ
Explain the hearing of reptiles
- have middle and inner ears
- only crocodile and some lizards have true outer ear
- crocodiles and most gecko species can close their ear cavities
- middle ear made of Tympanum( made up of two bones, stapes and extracolumella) held in a cavity of air
- snakes lack external ear and Tympanum but can process low frequency airborne sounds.
- snakes mainly pick up vibrations transmitted via quadrate bones of the jaw conducted via the ground
Briefly explain heat detection
-Certain snakes can remotely detect warmth making use of heat receptors
- Python only south african snake with heat detection ability
- receptors situated in shallow pits on labial scales of upper and lower jaws
- allow snakes to detect warm bodied prey in total darkness
- may also be used to detect optimal basking spots
-pit vipers have advanced stereoscopic infrared vision
Explain reptile breading behaviour
- usually early spring snakes get together and mate
- male follows scent trail left behind by female
- once found male will flick tongue in and out to inspect her for mating potential
- male then twists base of his tale under hers and will copulate with one of two penises(hemipenes, lizards also have this)
- 4-8 weeks later females selects a suitable egg laying sight( suitably protected)
Explain the differences between oviparous, viviparous and ovoviviparous with examples of each
oviparous(egg laying)- egg can be leathery(snakes and lizards) or rigid(crocodiles, tortoises ane geckos)
viviparous(give birth to live young)- some snakes or skinks
ovoviviparous(give birth to live young but majority of foetal sustenance gained from egg rather than placenta) some snakes, skinks and lizards, egg is retained in females body until birth. Eggs develop in mature animals oviduct until they emerge as smaller versions of the adult
Name some snake species under the 3 breeding types
Oviparous- mambas, cobras, boomslang, house snakes
viviparous - rinkhals, common slug eater, mole snakes
ovoviviparous- most adder species
What is the breeding method of a spotted skaapsteker
They lay eggs if partially developed embryos. Skaapsteker eggs take 2 weeks instead of 3 months to hatch after being laid. They are evolving to viviparity(live birth)
Explain reptile egg composition and differences with amphibian eggs
-Eggs of reptiles and birds have three sacks filled with fluid held within a protective leathery calcareous shell
- reptile eggs are able to tolerate far greater range of environmental conditions and thus allowing reptiles to be far less water dependent
- after three months after egg laying, young snakes equipped with an egg tooth(sharp ridge at the top of the snout) will slit the eggshell from the inside
- egg tooth is shed not long after hatching as it has no further use.
- hatchling resemble adult snakes and in most venomous species the young snakes already have fangs and venom glands
Name the 3 functions of reptile eggs and their three sacs
1) protect the embryo from being physically damaged
2) are permeable to gasses which are needed for metabolism
3) slow down water loss so the eggs can be incubated in relatively dry conditions
Explain parental care in reptiles
-very few species show parental care
- female nile crocodiles will protect her incubating egg filled nest for a certain period.
- certain lizard species will attend to their nest until eggs have hatched
- some snakes such as rock python and rhombic skaapsteker will coil around their eggs throughout incubation to protect and regulate temperature of eggs assisting in incubation
- rock python will remain with hatchlings for more than two weeks
Explain growth and skin shedding in reptiles
- as they grow they periodically shed their skin(sloughing)
- crocodiles, turtles, tortoises and terrapins shed their skin continuously due to flakes of skin being lost in reaction to uninterrupted growth of cells in the dermis layer
- skin shedding in snakes and lizards happens in a cyclical pattern with large patches or complete outer skin shedding all at once.
- in juvenile snakes skin shedding may take place 15 times a year and 4-5 times in adults depending on the growth rate
- in snakes or lizards with transparent eye lids period of shedding is evident by milky hue over the eye
- may go into hiding during this time due to the restrictions to vision making them venerable.
- before skin shedding starts they will bask in selected spots for longer in order to speed up development of new skin, thus shortening the venerability period
- rate if growth determined by availability and availability and quality of food.
- older snakes increase in girth not length and grow continually
- sexual maturity reached between 10-20 years old
Explain reptile venom in depth
- no lizard species is considered venomous in south africa
- some lizards do produce toxins in their saliva that have venomous action but not medically significant to humans
-this group known as venom clade include all snakes, agamas, chameleons and monitors - 151 species of snake in south africa, more than half have fangs and are technically venomous, 37 species could cause harm to humans and 16 life threatening
Name the 3 broad groups snake venoms are classified in
Hemotoxic- acts on cardiovascular system(heart and blood)
cytotoxic- localised action at the bite site and can be tissue destroying
Neurotoxic- attacks the nervous system( the brain)
What are the other types of snake toxins specific to types of cells ?
Cardiotoxin- heart
myotoxin- paralysing muscle
nephrotoxins- affecting the kidneys
What is snake venom ?
-A specialised salivary excretion and its active component consists mainly of proteins and peptides(amino acids)
What are the advantages of snake venom why do snakes have it ?
-Defence
-capturing and killing of its prey and speeds up digestion
- venom digests food from within
- more venamous snakes in cold areas because there rate of digestion is lowered due to them being ectotherms
Spitting snakes and their venom how does it work and why do they spit their venom?
-They do not spit they squirt
- pressure placed on the venom glands forces venom along the ducts and down the hollow fangs.
- close to the tip of the vangs is a opening placed at a right angle to the fang which directs venom from the mouth of the snake
- can squirt up to 2 and a 1/2 m based on size of the snake
- sprayed in the general direction of potential danger or movement
- used to defend themselves
- can inject same venom when biting
- rinkalls can only squirt from raised position while cobras can from any position
Name a few examples of sakes with neurotoxic venom as well as the typical symptoms when bitten
Black mamba
Green mamba
Snouted cobra
Cape cobra
Coral shield cobra
Forest cobra
Runkhals
State of panic, tingeling sensation at bite site, moderate swelling in some cases, sweating, dryness of throat, hypersalivation, paralysis of tongue and larynx, nausea, vomiting, respiratory distress, unconsciousness may occur between 10 min to an hour after bite
If not treated death will occur due to respiratory failure and cardiac arrest
Name a few examples of snakes with a cytotoxic venom with and explanation of the symptoms
Puff adder
Gaboon adder
Berg adder
Mozambique spitting cobra and black necked cobra ( also slightly neurotoxic)
Immediate unbearable pain at bite site. Watery blood oozes from site of bite within 30 min, gross swelling, shock will develop, nausea or vomiting may occur, spitting cobra venom may produce drowsiness as specially in children
