Eye, Ear + Olfactory System Anatomy - EXOTIC SPECIES

Question 1

Avian eye - main anatomical difference?

Answer 1

the eyeball almost fills the orbit (exophthalmic)
reduced eye movement
the long neck and mobile occipitoatlantal joint compensate for this lack of movement
the lower lid is the larger and more movable, so is easily seen
The cornea is thin and strongly curved

Question 2

which exotic species has no tapetum lucidum?

Answer 2

avian
very developed third eyelid though (nictitating membrane)
Retractor bulbi muscle is lacking
Retina has no vessels

Question 3

Retina of birds?

Answer 3

retinal vessels impair range of wavelengths detected than mammals (UV) stress, hunting/twitching
Presence of pecten (unique to birds - provides blood supply to the retina)
Pecten typically is black; melanocytes; warming and enzyme function

Question 4

Birds - presence of scleral ossicles which form the scleral ring:

Answer 4

Bones within the sclera of the eye
Fused/developed to different degrees depending on species
Function uncertain - offers protection?
Aids vision; stabilised focal length (lens position)
Outside forces such as water/air
also found in reptiles and some fish

Question 5

cryptochromes?

Answer 5

molecule that reacts to magnetic fields
helps species with migration - they can see magnetic fields

Question 6

nocturnal vision?

Answer 6

increase available light
increase light sensitivity

Question 7

increase available light?

Answer 7

wider aperture (eye/pupil)
some mammals use tapetum lucidum
some bird species have tapetal-like structures but these are often not considered a ‘true’ tapetum lucidum

Question 8

increase light sensitivity?

Answer 8

ISO setting; Rod density
Rods = photoreceptors for light:dark
thinner rods
more of them

Question 9

acuity and resolution can be adversely affected?

Answer 9

detecting more light usually makes able to differentiate objects

Question 10

olfactory bulb size?

Answer 10

small in size

Question 11

olfaction birds?

Answer 11

has been thought to not be well developed some species such as vultures have incredibly developed capabilities
nasal conchae vary depending on olfactory capability for species of known ability
No vomeronasal organ is present thus may be unable to detect pheromones
It may just be that we don’t know yet

Question 12

avian ear?

Answer 12

there is no auricle (Pinna)
they can have ear lobes (e.g. hens)
some birds have an operculum (owls) which is an accessory structure of the external ear, aids sound location
middle ear columella (equivalent of stapes in mammals)

Question 13

herpes corpuscle?

Answer 13

detecting vibration and movement
ducks have very sensitive beaks - used for nosing underwater
beaks are very sensitive

Question 14

reptilian ear - main anatomical differences?

Answer 14

presence of scleral ossicles (scleral ring) in lizards and chelonians

Question 15

eyelids reptiles?

Answer 15

these are fused in snakes and cannot move, they fuse to form the spectacle (transparent coverage for protection)
issues with dysecydis

Question 16

reptilian olfactory organ?

Answer 16

very well developed in snakes and lizards
vomeronasal organ is present and receives data from tongue, not the oral cavity
olfaction is important in courtship and mating as well as hunting

Question 17

reptilian ear - anatomical differences in relation to mammals?

Answer 17

absence of external ear (except ear lobes in crocs)
tympanic membrane is not as we know it
middle ear columella (like birds)
cochlear duct is not coiled
BUT many able to detect vibration
hearing is not as we think

Question 18

fish eyes have three main functions - what are they?

Answer 18

collecting light, accommodation (focussing images on the retina) and transforming images into neural signals

Question 19

level of light dependent on? - fish

Answer 19

depth and factors such as sediment
may have scleral ossicles

Question 20

main anatomical differences in relation to mammals - fish?

Answer 20

the eye continues to grow throughout its life and it changes and adds new cells continuosly unlike mammals
can adjust focus by moving the lens closer to or further from the retina (like magnifying glass)
lens needs to be more mobile due to the water refractive index
the falciform process is attached to a muscle (retractor lentis) that pulls the lens ‘backwards’ from the relaxed position to focus on distant objects

Question 21

lens of fish?

Answer 21

lens are spherical or slightly flattened depending on lens position
tapetum lucidum may/may not be present
eye position and diet (not just fish)

Question 22

PER EYE - fish?

Answer 22

2 corneas
2 irises
1 lens
1 retina (two hemiretinas)
one opic nerve

Question 23

fish olfactory organ?

Answer 23

nare

Question 24

main anatomical differences in relation to mammals - olfactory organ of fish?

Answer 24

nostrils can be close to the eye or distant
nostrils connect to a nasal sac, there are nerve endings in this sac that passes info onto the olfactory bulb and therefore brain

Question 25

fish olfaction, relative allocation of brain volume?

Answer 25

a lot of space given to olfaction but does vary with species e.g. stickleback and pike vs sharks or salmon

Question 26

main anatomical differences in relation to mammals - fish ear?

Answer 26

fish with swim bladders detect vibrations/movement in the water using lateral lines (sense organs) hearing not as acute if no swim bladder lateral lines pass information to the inner ear which relays back to swim bladder and therefore brain Mechanoreceptor Neuromast cells

Question 27

neuromast cell?

Answer 27

vibration and electrical current detection

Question 28

neuromast cells - fish, two main types:

Answer 28

elasmobranchs (and some others): specially developed neuromast cells - electroreceptors - in elasmobranchs, these form the Ampullae of Lorenzini - Catfish (murky water) and Electric Eels (own current)

Question 29

which animals can see on the IR spec

Answer 29

mosquitoes, bat, vipers, salmon