Sensory Adaptations in Exotics Flashcards
Describe and explain the significance of infrared sensors in some snakes
Enable snakes to see in ‘infrared’ which assists with night vision, & hunting small, or very still prey
This ability allows them to detect prey & pinpoint where to strike
Plays a fundamental part of natural behaviour so in captivity an owner must be aware otherwise a snake may suffer from issues such as anorexia
Name some snakes that uses infrared sensors
Pythons
Boas
Pit Vipers
What is the vomeronasal organ and what is its importance?
Vomeronasal organ is important for activating the accessory olfactory organ.
This organ contains chemosensory stimuli which influence social or reproductive behaviour
List the species that it is present in and briefly state how the anatomy varies across species
Present in many species:
Amphibians
Lizards
Snakes
Many over domestic
species
(not present in fish,
birds or chelonians)
Anatomy & location varies across species and may or may not include a connection to the mouth through the nasopalatine duct
In knowing that snakes have a well developed vomeronasal organ, what is the significance of removing the tongue? Mention also the location of the organ
Organ is located on the roof of the oral cavity
Implications of tongue removal are…
Describe the anatomy of reptile ears
External ear absent/diminished in most species
(except crocodiles)
Tympanum absent in some species
Where it is present it is superficial e.g. Flush with skin in reptiles
What is the function of the anatomy of snake hearing?
No tympanic mebrane (not deaf)
Quadrate bone (takes place of ear drum)
- Jaw flexibilty
- Connects stapes (columella) to oval window of cochlea
Hear in low frequencies
Describe the anatomy of birds ears
Outer, middle & Inner ear (like mammals)
Specialised feathers instead of pinna
Can have ear lobes (ornamental)
E.g. Chickens
Some birds have operculum
Accessory structure, aids sound location
Owls have this
X2 Tympanic membranes in songbirds
-second is made of smooth muscle - songbird can contract this to prevent
deafening themselves
Short external auditory meatus Single auditory ossicle (like reptiles)
What is the function of the anatomy of bird hearing?
2nd most important sense
Key for nocturnal birds
Homing pigeons- ability to sense magnetic forces to get home
Echolocation in some species
E.g. Cave swiftlets
Birds can regenerate their inner ear hair cells if damaged
Mammals suffer permanent hearing loss
Describe the anatomy behind owl ears
Tightly packed rim of facial feathers (cf pinna)
Sound –> external auditory meatus
Left & right external auditory meatuses are different shapes
Helps localise sound
What is the function of the anatomy of owl ears
Asymmetry enables precise pinpointing of prey
Intensity & timing of sounds
Horizontal and vertical planes
Compare the inner ear of birds and reptiles to that of a mammalian ear
Simpler structure compared to mammals
- One auditory ossicle (bone) columella (equivalent to stapes) - Cochlea duct is not coiled Poor hearing
Describe the anatomy of fish ears
An otolithic inner ear
Lateral Line:
Runs just below surface of the skin, along the sides of the body.
Covered by pored scales.
What is the function of the anatomy of fish ears?
Fish are capable of detecting acoustic information through:
Lateral line is used to detect movement, vibration & pressure gradients in surrounding water
- Detect obstacles, swim in schools, predator avoidance
How is vision under water different to vision in air?
Vision in Air
Strongly refracted through cornea
Corneal focus
Vision in Water Cornea/water have similar refractive index Lens focus
Describe the anatomy of the fish eye
Huge variation between the species
Most can see colour (some see UV light) Rod:cone ratio varies depending on depth they live at Main differences: No lacrimal glands (tears) Rigid, immoveable iris (pupil are fixed size) Pupil fixed Lens: Spherical, protrudes through iris
Light focussed by changing position of lens in relation to retina
Describe the anatomy of the avian eye
Eyes are relatively large in relation to the socket (exophthalmic)
No tapetum lucidum Avascular retina Less light scatter from blood vessels, higher visual acuity Pecten Highly vascularised, thin, highly folded Nutritive role (retina)?
Describe avian vision
Colour vision varies among birds – some (not all) see colour
Many nocturnal birds also see UV light
Proportion of Diurnal birds: cones
Up to 80% in pigeon and chicken
Dim the lights to ease handling/catching
Nocturnal birds: rods
What are some clinically relavent facts we need to remember about the avian eye?
- Note the normal appearance of pecten
Do not confuse for retinal detachment or other pathology- Head trauma
Common in birds of prey
Remember – you must triage and provide first aid to all species
If destroyed, euthanise
- Head trauma
Describe the anatomy of squamate eyes, including spectacles
Retina is avascular
\+/- papillary cone (lizards, some snakes)
Snakes and some lizards have spectacles
Why is learning about spectacles clinically relavent?
Fused eyelids, transparent
Subspectacular space
Shed during ecdysis (colour change)
Dysecdysis:
Retained spectacles after shedding
Correct the husbandry
Rehydration = important
Bathe in warm water daily
Apply eye lubricant
Gently lift the spectacle off the eye using a wet cotton bud, from the very
edge of the eye.
Surgery to remove the spectacle is rarely required but may be needed if sever. Never just pull skin off!
Describe the anatomy of eyelids in reptiles and birds
Nictitating membrane
Present in reptiles
Very developed in birds
Striated muscles
Rapid sweeps, clean cornea
Lower lid
More mobile
Larger (birds)
What is the function of Scleral Ossicles in reptiles and birds?
Bones within sclera
Protection and support
Aid function of ciliary muscles (visual accommodation)
Esp. night vision (nocturnal species)
Birds and reptiles
What species have fovea present in the eye?
Present in birds, reptiles, fish & primates
Diurnal species (Especially raptors) have 2 fovea
What is the function of fovea?
The high density of rods & cones provide a sharp vision and visual acuity.
Describe the anatomy of the pineal gland
Endocrine gland, in brain
Most vertebrate species
Describe the function of the pineal gland
Produces melatonin
Sleep/wake cycles Responds to light/dark
Describe the anatomy of the parietal eye
Many lizard (and amphibian) species
“3rd eye”, photoreceptive structure
Usually on top of head
Lens, cornea, retina
Describe the function of Parietal Eye
Produces and secretes melatonin
Light/dark, sleep cycles, hormone production, thermoregulation
Name and explain the test used to asses vision. What species can it not be used on and why?
Pupillary Light Reflex
In mammals, the pupillary light response (PLR) is used to assess vision. Shining a light in the eye results in constriction of the pupil. Also affects contralateral eye - called consensual PLR.
In birds and reptiles, the consensual PLR cannot be assessed – as both eyes are under independent control.
What are mydriatics? What species can it not be used on and why?
In mammals, we can apply topical chemicals called mydriatics (e.g. atropine) to the eye to cause pupil dilation.
We cannot do this in birds and reptiles - the iris and ciliary muscles are skeletal muscle (not smooth)
-under voluntary control
