Lecture 4 Flashcards
What class to reptiles belong to
Reptilia
What are the 4 main orders of reptiles
1) Crocodilia: alligators and crocodiles
2) squamata: snakes and lizards
3) chelonian: turtles and tortoises
4) rhyncocephalia: tuataras
What class to amphibians belong to
Amphibia
What are the 3 main orders of amphibians
1) gymnophiona: caecilians
2) Anura: frogs and toads
3) cuadata: salamanders and newts
Describe what it means for reptiles and amphibians (herptiles) to be “cold blooded”
This means they are ectothermic
They are unable to generate large amounts of heat internally, so their body temperature depends on the environmental temperature
Some reptiles can markedly raise body temperatures by ___
Muscular contractions
Leatherback sea turtle swimming
(Pythons shiver when incubating eggs)
Define herptiles
Mainly regulate body temperature via behaviour
Ex. Sunbathing, changing skin color, coiling or uncoiling
True or false
Thermoregulation is less important in hot environments
True
It is more important in cold environments
Describe ecothermy in reptiles/amphibians
Related to energy conservation
These animals metabolism depends on body temperature
This allows many herptiles to survive on very small amounts of food (most being to maintain body temp)
Temperature of herptiles depends on access to temperatures within the POTZ, what is this?
Preferred optimal temperature zone
(Changes with species)
This is the range of temperature in which the animal can perform all necessary metabolic functions
Why is it critical that a sick patients environment is at POTZ when administering medications? What could happen if it is not at POTZ?
This allows proper absorption, metabolism and excretion of the medications
If not, it can lead to no response to treatment, lack of healing, overdose or death
Heat sources such as heat rocks and red light bulbs are not acceptable in the herptiles world, what is the best source of heat?
Non light providing sources such as ceramic bulbs or heat mats that go under the tank
What is something that is often unknown about UVB or UVA bulbs
These bulbs lose the ability to provide these nutrients before they stop lighting up
Recommended to change every 6 months
Why is it difficult to give SQ injections it reptiles
Because they have very little space
Describe the dermis of reptiles
Dense connective tissue
Contain Blood and lymph vessels, nerves and chromatophores (pigment containing cells)
Chromatophores allow some lizards to change skin color and pattern
Contain osteoderms: bony plates within the dermis of some lizards and crocodilians
Describe the epidermis of reptiles
Scales and scutes of reptiles are formed by epidermal folds in most reptiles, they vary in size and shape. It is keratinized
What are some other epidermal structures than may be present on reptiles
Crests Tubercles Spines Dewlaps Keels Horns Barbles
Describe the integument of turtles/tortoises
Scales and scutes are thick epidermal plates
Nomenclature aids in species identification and medical recording
Cervical scute: first scute at the base of the neck area
Vertebral scutes: run down the center of the shell (numbered)
Pleural scutes: lay right over the lungs (numbered and labelled left or right)
Marginal scutes: the border of the shell (numbered and labelled left or right)
What is ecdysis? Describe this?
Shedding of the skin
Occurs with growth and in response to injury
Shed in pieces or in one large piece
Skin does not grow with the animal, so the body outgrows the skin and the animal must shed it
The shed skin is called: exuvia
Enzyme containing lymph secreted between old and new layer (reabsorbed before ecdysis)
The skin color fills (spectacle opacifies)
Mechanical rubbing on objects aids in shedding
It is controlled by the thyroid gland
What is dysecdysis? Describe this
Abnormal or difficulty shedding
Usually due to poor husbandry: low humidity, no objects in enclosure to rub on, malnutrition, dehydration etc
Can be from skin wounds, disease, dermatitis, parasites
If not corrected it can lead to Dyspnea, dermatitis, future shed issues, loss of toes or tail tips
What can be done to help dysecdysis
Correcting underlying problem
2 hour warm water baths (softens shed and you can pull it off)
What is different about amphibian integument? What are drink patches?
It is extremely permeable: they absorb water directly from the environment (don’t drink)
“Drink patches” are areas of increased permeability on ventral surfaces
Describe the epidermis of amphibians
Single or few layers or keratinized cells -very thin
Aquatic amphibians do not have keratinized cells
Amphibians regularly shed layers of epidermis and usually eat the exuvia
Describe the dermis of amphibians
Contain chromatophores and glands
Glands produce secretions which help to protect the animals skin (because they don’t have a thick layer of keratinized skin, they need this instead)
Very little space in salamanders and caecilians
Anurans have looser attachments of dermis
May have toxic secretions produced by some glands within the dermis and epidermis (defends mechanism)
What does the reptilian and amphibian nervous system depend on
Spinal segmental reflexes and locomotor centers for control of movement
Describe the nervous system of reptilians, what reflexes are present? How are some of them used?
Tongue withdrawal, jaw, pedal and tail reflexes are all present
When monitoring anesthesia in reptiles OTHER than snakes; use the corneal and palpebral reflexes (snakes do not blink)
In snakes: the tongue withdrawal reflex will be maintained at the surgical plane of anesthesia
Describe the vision of reptiles
Iris made up of skeletal muscle under voluntary control (PLR: consensual reflexes not seen)
Lower lid is usually more mobile than upper lid (upper lid is more mobile in mammals)
Nictitans: well developed, and mobile in many reptiles
Some species of lizards have a thin transparent lower lid to allow for
some vision when lids are closed
What is the spectacle found in snakes and some lizards
A clear fused scale on the eye above the cornea (have a small space in between: contains tear film)
Tears drain into mouth through a nasolacrimal system
These animals have no true eyelid
In caecilians, the eyes are covered with skin
Eyelids are absent in some aquatic species
Most reptiles have poorly developed extraocular muscles (have to move entire head to look around) what is the exception to this?
Chameleons: their eyes move freely and independently of one another
Describe the lacrimal and harderian glands? What’s different about chelonians,
Present in most reptiles and amphibians: produce secretions that combines to form the tear film
Chelonians: no nasolacrimal ducts, tears spills over the lid margins
What happens in some amphibian eyes when swallowing?
protrude ventrally into the oral cavity when swallowing
Describe the eye in reptiles
Contain ossicles: sclera bones present in most reptiles (not snakes or crocodilians)
Lens: more fluid in reptiles than mammals (more rigid in snakes) this allows for further accommodation
Parietal (rudimentary) eye in some reptiles (space - not an eye thought to be associated with light cycles)
Describe what’s different about accommodation abilities in chelonians and snakes
Accommodation:
1) chelonians: lens is squeezed through the pupil to adjust its size
2) snakes: lens moves back and forth due to pressure changes within the aqueous and vitreous humors (doesn’t actually change shape)
What is hypovitaminosis A
One of the most common disease affecting turtles and tortoises
Usually from a diet deficient in Vit A resulting in abnormal functioning of skin
Signs: swollen eyelids, loss of appetite, weight loss, raw skin with secondary bacterial infections, nasal discharge, abnormal development of eyes in embryos
Treated with Vit A injectable or dietary supplements (maybe also need to treat secondary bacterial infections -mucosal surfaces more prone to infection)
What is different about a snake ability to hear
Snakes: no external ears, columella articulates with the quadrate bone of the jaw: this allows snakes to be very sensitive to ground vibrations transmitted through the mandibles and converted to sounds
Snakes can hear aerial sounds but it is not as highly developed
Who are aural abscesses common in? What are they often secondary to?
Middle ear infections are common in chelonians
Can be secondary to hypovitaminosis A
Location of the heart varies in amphibians and reptiles, describe the location in some different species
Chelonians: on midline just caudal to the thoracic girdle, central to the lungs
Most lizards: within the thoracic girdle/space
Crocodilians and some lizards: farther back in the coelomic Cavity (abdominal cavity ish near the center)
Snakes: usually at the junction of the first and second third of the body length (fairly mobile within the coelomic cavity)
Describe the heart of most reptiles and amphibians. Describe the heart of crocodilians
3 chambered with two atria and one ventricle
Crocodilians: 4 chambered heart unlike mammals or avians
How is there no mixing of oxygenated and deoxygenated blood in a 3 chamber heart (only one ventricle)
The ventricle is divided (septum), it is just not considered 2 Chambers
Why is it difficult to auscultate reptilian hearts? What can you do instead?
You usually can’t heart it, very slow, difficult to find, in turtles you can hear past shell
You may be able to watch cardiac movement through the skin
What does heart rate depends on
Species, size, temperature, activity level and metabolic function
In lizards, what is the vasovagal reflex
Induces a drop in heart rate, blood pressure and a catatonic state
Triggered by applying gentle pressure to both eyeballs through closed eyelids (recover when pressure is released or with mild stimulation)
True or false
Reptiles can’t survive long without breathing
FALSE
reptiles can survive long periods without breathing
Respiration is driven by
Oxygen levels in the blood (in mammals it’s CO2 levels in blood)
Lizards tend to experience severe respiratory depression while under anesthesia, so it is important to provide____
Positive pressure ventilation (2-4 breaths per minute generally)
If they stop breathing on their own, which can happen, the anesthesia will wear off
Where is the glottis of most reptiles and amphibians located? Describe the glottis in snakes? Is there an epiglottis present?
In the rostral portion of the oral cavity
The glottis is very mobile in snakes and protrudes from the mouth to allow respiration during ingestion of prey
There is not often an epiglottis present, there is paired arytenoid cartilages that border the glottal opening, that open and close with respiration
Is it easy to pass an endotracheal tube in reptiles? Why?
Yes because the it is clearly visible and distinct from the esophagus
Describe the vocal ranges of reptiles
They have no vocal cords
The only vocalizations possible are hissing, grunting, or bellowing
Frogs and toads: vocal sacs arise from the trachea
What is the glottal keel
Present in some species of snakes that increases the volume of vocalizations
This structure found at the glottal opening also makes intubation difficult
Reptiles have no diaphragm, how do they breathe?
By the action of the intercostal muscles and ribs and parts of the axial musculature used for respiration
Do not restrain them too tightly
Describe the amphibian respiratory system
Simple sac like lungs
Some salamanders have no lungs (they have cutaneous respiration: absorbs air through the skin)
Pulmonary ventilation from pumping of the buccal cavity and pharynx (necks gets bigger/smaller) gas exchange occurs through mucous membranes of the buccal cavity, pharynx and cloaca
Gills may be present in young amphibians
Some reptiles can be carnivorous, omnivorous or herbivorous
Snakes, crocodilians and adult amphibians are strict
Carnivores
What is the function of the deeply forked tongues of snakes and lizards
Function as a particle delivery system for the vomeronasal organ (accessory olfactory organ) (smelling air by tasting it)
Allow for detection of particle gradients
Describe the tongue of chameleons
Specialized projectile tongues designed for capturing prey from long distances (sticker end which the prey stick to)
Describe the tongue of turtles and tortoises
Typically thick, fleshy and relatively immobile
describe the tongue of crocodilians, what structure of the oral cavity aids them when being under water
Immobile and attached to intermandibular space
Muscular flaps from base of tongue and dorsal pharynx allow for opening of mouth while submerged without ingesting or inhaling water (blocks off the throat)
Describe the oral cavity of amphibians
Tongue used to capture prey (most amphibians)
Salamanders: tongue is flipped to pretend food (lingual flipping)
Has numerous salivary glands to provide stickiness
Some have venom glands (snakes and lizards) which is a modified salivary gland with a canal that runs down the tooth
Describe the dentition of tortoises and turtles
They do not have teeth, they have Tomia (keratinized beaks)
Other reptiles have teeth
Describe the dentition of snakes
Have 6 rows of teeth: two mandibular, two maxillary, two palatine/pterygoid bones
Snakes without venomous fangs are called
Aglyphous snakes
Dentition of venomous snakes
Specialized dentition for delivery
Venom teeth: hollow with an opening near end where venom is expelled
Fangs receive venom through a duct from a venom gland at its base
Contraction of muscles around venom gland forces venom out from the fang
True or false
Snakes can control the amount of venom delivered with each bite
True
Describe the dentition of most amphibians
Most have teeth
Caecilians and salamanders: both maxillary and mandibular teeth (some have palatal teeth)
Some anuran species have a maxillary dentition
Some have odontoid process: cutting plates on rostral mandibles of some frogs
Describe the esophagus in reptiles and amphibians
Reptiles: thin and distensible: unique morphology reflects type of prey
Amphibians: very short and wide (especially in anurans)
Describe the stomach of reptiles
Variable in size and shape
Snakes: highly distensible
Crocodilians: thick muscle comparable to avian gizzard
what are anurans capable of doing with their stomach?
Anurans capable of prolapsing the stomach through the mouth
Used for emptying the stomach if they ingest something undesirable
Gastric prolapse can be a terminal event in dying animals
Can be seen with some methods of anesthesia
Describe the intestinal tract of reptiles
Varies according to diet
Herbivores: longer than carnivores
Snakes: relatively straight (not a lot of coiling)
Colon: large and complex in herbivores (hind gut fermentation)
Cecum: site of hindgut fermentation in herbivorous lizards and chelonians
Liver: bilobed and large
Describe the cloaca
common outflow tract for GIT and urogenital tracts (all reptiles and amphibians)
Three chambers, similar to birds: coprodeum, urodeum, proctodeum
Describe the reptilian kidney
Have a renal portal system arising from the veins of the pelvic limbs and tail (avoid injection of meds in caudal half)
Describe the amphibian kidney
Some amphibians excrete ammonia as a nitrogenous was product -other excrete urea, or Uric acid
These have no ability to concentrate their urine
Urinary bladders and cloacal anatomy similar to reptiles
Male reptiles have internal testes located in the
Dorsal coelomic cavity
In male reptiles, the ductus deferens leads from the testes to the
Dorsal wall of the urodeum
They possess a copulatory organ such as a phallus or paired hemipenes
Most male reptiles have a sexual portion to the kidney tubules, what does this do
Develops in response to high levels of circulating sex hormones and provides secretions that contribute to the seminal fluid
Describe how copulatory organs vary in structures in male reptiles
Crocodilians and chelonians: phallus of erectile tissue rising from floor of cloaca
Snakes and lizards: paired hemipenes everted from the tail base through the vent (caudal to the vent)
Describe the female reptilian anatomy
Paired ovaries in dorsal coelomic cavity
Paired oviducts lead to cloaca and end at the genital papillae on dorsal wall of the urodeum
In viviparous species, describe the fetus development
Viviparous: birth of live young
Fetuses are retained and nourished in uterine portion of the oviduct
In oviparous species, describe birth of young
Birth of young by laying eggs
Many reptiles dig nests to lay eggs in
Without a suitable nested many females will not lay and experience dystocia
Chelonians and some lizards may dig deep holes to
Deposit their eggs into and leave after
After oviposition or parturition, reptiles are often not involved with the care of eggs or offspring, what are the exceptions to this
Crocodilians: protect their nests and young for a period of time following hatching
Pythons and cobras: protect their nests until hatching
Describe incubation of eggs
Development and hatching requires proper temperature, humidity and gas composition of the nest
Incubation time and temperatures vary in species
Reptile eggs should NOT be rotated during incubation like with avians
Describe sex determination of reptiles with incubation
Sex can be determined by genotype or temperature at which eggs are incubated
Females: heterozygous (ZW)
Males: homozygous (ZZ)
Opposite in mammals
In some species they do not have sex chromosomes, describe how sexes are made in incubation
Higher incubation temperatures produce males in crocodilians and lizards (opposite in chelonians)
Temperature range within the nest allows production of mixed clutch of hatchlings
Artificially you can determine the sex of the animals
True or false
Snakes have no real sexual dimorphism
True
There is often no good way to differentiate sexes
In some species, pelvic spurs are present and can be be larger in males, what are these
Remnants of pelvic limbs and provide tactile stimulation to females
Describe a Male chelonians vent
May have a concave plastron and more distally located vent than females
Allows closer apposition of the cloaca when the male mounts the females
What is an example of a species of lizards that show obvious sexual dimorphism
The male jackson’s chameleon has three well developed horns on its face
Describe different sexual dimorphism in amphibians
Poison dart frogs: males have enlarged toe pads
Anurans: males may have Large tympanic membranes
Salamanders: males have prominent cloacal glands
Most caecilians (serpentine amphibians) are
Viviparous
Most anurans and salamanders are
Oviparous
What are amplexus frogs and toads
These fertilize eggs as they are laid while grasping the female
What are spermatophores in salamanders
Packets of sperm deposited onto substrate by male salamanders
These are picked up by the females cloaca in the spermatotheca (pocket in the cloaca of female salamanders where sperm can be stored)
When amphibians lay eggs, they are often laid in or near
Water
There is some parental care of eggs/young in what amphibians
Anurans and most salamanders
Larval anurans (Tadpoles) have completely aquatic lives prior to
Metamorphosis
Tadpole metamorphosis is usually complete within
90 days
What is tadpole metamorphosis stimulated by
Thyroid hormones
What is the life cycle of a frog
Egg
Embryo
Tadpole
Front legs break through
Pulmonary breathing starts
Tadpole frog
Adult frog
Describe the snake skull
Extremely mobile
Mandibular symphysis is connected by ligaments that allow the jaws to move independently of each other
This is to allow the mouth to open extremely wide for ingesting large prey
Describe the shell of a turtle
The shell is a part of their skeleton -actually connected
It can grow and heal like any bone
They do have a backbone/spine that is connected to the shell
Most of the space inside is occupied by lungs
What is tail autonomy
A defensive mechanism: species will drop their tail that will continue to wiggle to distract predators
Present in some lizards and salamanders
These species have a “fracture plane” on the tail where the tail is designed to break off from that results in very little blood loss
Lost tail can regenerate but it is often stiff and cartilaginous
What is metabolic bone disease
Caused by an imbalance of calcium, phosphorus and vitamin D3
Proper diet, temperature and light will prevent this
Symptoms: swollen mandible, curvature if the tail and possibly spine, decreased bone density on radiographs (will not appear as white) (weak, fragile deformed bones)
What are some common reptile/amphibian species native to Saskatchewan
Plains garter snake
Greater short horned lizard
Prairie rattle snake
Tiger salamander
