Amphibians and reptilian anatomy and physiology Flashcards
Class reptillia- four orders
Crocodylia (aligators and crocodiles)
Squamata (snakes and lizards)
Chelonian (turtles and tortoises)
Rhyncocephalia (tuataras)
Class Amphibia - three orders:
Gymnophiona (caecilians)
Worm/snake like amphibian
Anura (frogs and toads)
Caudata (salamanders and newts)
Metabolism of ectothermic animals
Reptiles and Amphibians (Herptiles) are ectothermic or “cold- blooded”
Ectothermic animals are unable to generate large amounts of body heat internally.
Body temperature depends on environmental temperature
Some large reptiles can markedly raise body temperatures by muscular contractions
Leatherback Sea Turtle (swimming)
Pythons (shiver when incubating eggs)
Environmental thermoregulation for amphibian and reptiles
Herptiles – mainly regulate body temperatures via behavior
Sunbathing, changing skin colour, coiling or uncoiling
Thermoregulation less important if living in hot environments
Ectothermy is
Related to energy conservation
Animals metabolism depends on body temperature
Allows many herptiles to survive on very small amounts of food
Depends on access to temperatures within the preferred optimal temperature zone (POTZ)
POTZ is
Range of temperature in which the animal can perform all necessary metabolic functions
Critical that an ill patient’s environment is at POTZ as well as when administering medications.
Providing a heat source is very important if keeping herps as pets, especially in a colder climate like Saskatchewan
Why is POTZ important for administering
This allows proper absorption, metabolism and excretion of the medications
If not, can lead to no response to treatment, lack of healing, overdose or even death
Size of SQ space for reptiles
Limited SQ space so it is difficult to administer SQ injections
Dermis of reptiles
dense connective tissue
Blood and lymph vessels, nerves, and chromatophores (pigment-containing cells)
Chromatophores allow some lizards to change skin color and pattern
Osteoderms: bony plates within dermis of some lizards and crocodilians
Epidermis on reptiles
Epidermis- scales and scutes of reptiles are formed by epidermal folds in most reptiles. They vary in size and shape. The epidermis is keratinized
Other epidermal structures may be present
Crests, tubercles, spines, and dewlaps, keels, horns, barbles
Scale and scute (thick epidermal plates e tortoise) nomenclatures- aids in species identification and medical recording
Ecdysis for reptiles is
Shedding of the skin
Occurs with growth and in response to skin injury
Shed in pieces or in one large piece
Exuvia means
shed skin of reptiles
Ecdysis is controled by
Controlled by the thyroid gland
Cells replicate new epidermis
Enzyme containing lymph secreted between old and new epidermal layers
Skin colour dulls: spectacle opacifies
Lymph- reabsorbed prior to ecdysis
Mechanical rubbing on objects aids in shedding
Dysecdysis is and caused by
Abnormal shedding
Usually from poor husbandry
Low humidity, no objects in environment to rub against, malnutrition and dehydration
Can also be due to skin wounds, illness, dermatitis, and parasites
Fix by correcting problem and a 2 hour warm water bath
If not corrected can lead to dyspnea, dermatitis, future shed issues, and loss of toes or tail tips
Amphibian Integument is
Extremely permeable
Absorb water directly from environment
“Drink patches”: areas of increased permeability on ventral surfaces
Epidermis of amphibians
Single or few layers of keratinized cells
Aquatic amphibians - no keratinized cells
Amphibians regularly shed outer layers of epidermis and usually eat the exuvia
Dermis of amphibians
chromatophores and glands
Glands produce secretions which help protect the amphibian’s skin
little subcutaneous space in salamanders and caecilians
Anurans: looser attachments of dermis (more subcutaneous space)
Toxic secretions are produced where by amphibians
produced by some glands within dermis and epidermis
Defense mechanisms
Reptile nervous system
Depend on spinal segmental reflexes and locomotor centers for control of movement (same in amphibians)
Tongue withdrawal, jaw, pedal and tail reflexes are all present.
When monitoring depth of anesthesia in reptiles other than snakes, you can use corneal and palpebral reflexes.
In snakes, the tongue withdrawal reflex will be maintained at the surgical plane of anesthesia.
Reptile iris look like
iris made up of skeletal muscle under voluntary control
Pupillary light reflex: consensual reflexes usually not seen
What does lower eyelids doe for reptile
Lower lid usually more mobile than upper
What is unique about some lizards eyelids
Some species of lizards have thin, transparent lower lids
Allows for a degree of vision even when lids are closed
Nictitans are
well-developed, mobile in many reptiles
What do snake eyelids look like
Snakes, some lizards - no true eyelids
Clear, fused scale (spectacle)
Caecilians eyes are
eyes covered with skin
Eyelids absent in some aquatic species
Reptilian extraocular muscles
poorly developed extraocular muscles
Exception - chameleons; eyes move freely and independently of one another
Tear film for reptiles and amphibains
between cornea and spectacle in sub- spectacular space
Tears drain into mouth through nasolacrimal duct system
Chelonians eye ducts
no nasolacrimal ducts; tears spill over the lid margin
Lacrimal and harderian glands
present in most reptiles and amphibians
Produce secretions that combine to form the tear film
Amphibian eyes
often protrude ventrally into the oral cavity when animal swallowing
Ossicles are
Ossicles: scleral bones present in most reptiles (except snakes and crocodilians)
Lens of reptilian eyes
Lens: more fluid in reptiles than mammals (more rigid in snakes)
Vision accomidations in some species
Chelonians - lens is squeezed through the pupil
Snakes - lens moves back and forth due to pressure changes within the aqueous and vitreous humors
Parietal (rudimentary) eye in some reptiles
Hypovitaminosis A is casued by and treatment
One of the most common diseases affecting turtles and tortoises
Usually from deficient diet
Treated with vitamin A (injectable or dietary supplements)
Also need to treat any secondary bacterial infections, etc.
Some possible signs of Hypovitaminosis A:
Swollen eyelids
Loss of appetite and weight
Raw skin with secondary bacterial infections
Nasal discharge (runny nose)
Abnormal development of the eyes in embryos
Ears of reptiles and amphibians
Ears - both sides of head, usually caudal to eyes