Digestive (continued)

Histology of intestinal lining

Duodenal glands -

Cat

Pigeon

Cow (Ruminate)

Lobules of Liver

Cloaca of turtle

Eileen GarveyEileen GarveyArticle: Article: Comparative Morphology of the Eye

in PrimatesE. CHRISTOPHER KIRK*

The Anatomical Record Part A: Discoveries in Molecular, Cellular, and Evolutionary Biology

Volume 281A, Issue 1, Pages 1095-1103Published Online: November 2004

BackgroundBackgroundComponents of the eye:Components of the eye: – Rods:Rods: neurosensory cells which are insensitive to color, neurosensory cells which are insensitive to color,

absorb light over the entire range of the visual spectrum, absorb light over the entire range of the visual spectrum, and are most effective in relatively low intesities of light, and are most effective in relatively low intesities of light, such as shade, dusk or night time.such as shade, dusk or night time.

– Cones:Cones: neurosensory cells that are senstive to color, neurosensory cells that are senstive to color, absorb light in only one part of the visible spectrum (red, absorb light in only one part of the visible spectrum (red, green, blue), and function only in prescene of light that falls green, blue), and function only in prescene of light that falls into this wavelength.into this wavelength.

DiurnalDiurnal species are usually more active during the day when species are usually more active during the day when the light levels are in the range of cone mediated vision.the light levels are in the range of cone mediated vision.NocturnalNocturnal species are usually active at night when light levels species are usually active at night when light levels are in the range of rod mediated vision.are in the range of rod mediated vision.However there are many mammalian species that are However there are many mammalian species that are considered, considered, cathemeralcathemeral, which means they are active in both , which means they are active in both light and dark periods.light and dark periods.

http://rds.yahoo.com/S=96062883/K=eye/v=2/SID=e/l=IVI/SIG=11p2o91qj/*-http%3A//www.iupui.edu/~geotech/g337/lecture5/eye1.jpg

Background continuedBackground continuedIn the article, the morphological adaptations for In the article, the morphological adaptations for different activity patterns are compared with the different activity patterns are compared with the gross anatomy of the eye of primates.gross anatomy of the eye of primates.The size of the cornea places an upper limit on The size of the cornea places an upper limit on the maximum amount of light that the eye can the maximum amount of light that the eye can absorb.absorb.Nocturnal species increase the size of the Nocturnal species increase the size of the cornea compared to the transverse diameter of cornea compared to the transverse diameter of the eye so that it is possible to absorb more the eye so that it is possible to absorb more light.light.Diurnal species have smaller corneas compared Diurnal species have smaller corneas compared to the transverse diameter of the eye.to the transverse diameter of the eye.

HypothesisHypothesis

The goal of the analysis:The goal of the analysis:– Provide a quantitative description of the Provide a quantitative description of the

relationship between eye morphology and activity relationship between eye morphology and activity pattern in broad sample of primate species.pattern in broad sample of primate species.

– The researchers asked many questions; for The researchers asked many questions; for example:example:

Do nocturnal, cathemeral, and diurnal primates Do nocturnal, cathemeral, and diurnal primates exhibit systematic differences in eye morphology exhibit systematic differences in eye morphology as has been predicted by other studies conducted as has been predicted by other studies conducted on mammalian eyes?on mammalian eyes?

Methods and MaterialsMethods and MaterialsData were collected on eye and cornea size for 147 Data were collected on eye and cornea size for 147 specimens of 55 primate speciesspecimens of 55 primate speciesSamples were taken from preserved specimens that Samples were taken from preserved specimens that were frozen directly after the animal died or were were frozen directly after the animal died or were preserved in formalinpreserved in formalinEyes were removed from the orbit and cleanedEyes were removed from the orbit and cleanedEach eye was refilled to prevent it from collapsingEach eye was refilled to prevent it from collapsingA needle was inserted into the optic nerve and then A needle was inserted into the optic nerve and then the measurements were determinedthe measurements were determined Activity patterns and mean eye measurements Activity patterns and mean eye measurements were determined for all included taxawere determined for all included taxa

Methods and MaterialsMethods and Materials– Data/calculations included:Data/calculations included:

Activty Patterns D=Diurnal, N=Nocturnal, Activty Patterns D=Diurnal, N=Nocturnal, C=Cathemeral C=CathemeralMean transvers diameter in mmMean transvers diameter in mmStandard deviationStandard deviationMean transverse corneal diameter in mm Mean transverse corneal diameter in mm Ratio of corneal diameter and mean transverse Ratio of corneal diameter and mean transverse eye diameter (C:E ratio)eye diameter (C:E ratio)Example of calculations: Table 2Example of calculations: Table 2

CalculationsCalculationsTable 2: Summary of statistics comparing C:E ratios of primates grouped by

suborder and activity pattern

Diurnalhaplorhine

Nocturnalhaplorhine

DirunalStrepsirrhine

Cathemeralstrepsirrhine

Nocturnalstrepsirrhine

Number 30 2 6 5 12

Mean C:E ratio 0.51 0.74 0.73 0.75 0.83

StandardDeviation 0.03 0.06 0.02 0.03 0.04

Results and DiscussionResults and DiscussionC:E ratios varied between primates that were of different C:E ratios varied between primates that were of different suborders and had different activity patterns; however suborders and had different activity patterns; however within the same subgroup the functional morphology was within the same subgroup the functional morphology was consistent with previous testing results. consistent with previous testing results. – For example: diurnal species had smaller relative For example: diurnal species had smaller relative

cornea size than nocturnal or cathemeral speciescornea size than nocturnal or cathemeral speciesAs expected nocturnal species showed higher C:E ratios As expected nocturnal species showed higher C:E ratios compared to diurnal species compared to diurnal species Haplorhines had diurnal species with significantly lower Haplorhines had diurnal species with significantly lower C:E ratios than the nocturnal species.C:E ratios than the nocturnal species.Strepsirrhines had diurnal species with significantly lower Strepsirrhines had diurnal species with significantly lower C:E ratios than the nocturnal speciesC:E ratios than the nocturnal speciesCathemeral strepsirrhines had C:E ratios that were larger Cathemeral strepsirrhines had C:E ratios that were larger than the diurnal strepsirrhines and smaller than the than the diurnal strepsirrhines and smaller than the nocturnal strepsirrhinesnocturnal strepsirrhines

Summary Summary

Eye morphology changed consistently with Eye morphology changed consistently with activity pattern in primate subordersactivity pattern in primate subordersFor most suborders tested, such as For most suborders tested, such as strepsirrhines, and haplorhines, relative strepsirrhines, and haplorhines, relative cornea size was largest in nocturnal cornea size was largest in nocturnal species and smallest in diurnal speciesspecies and smallest in diurnal species

DiscussionDiscussion

Data supports the hypothesis that cornea Data supports the hypothesis that cornea size is largest for species that are most size is largest for species that are most active in dark periods compared to those active in dark periods compared to those that are active in the lightthat are active in the lightPrimates have evolved their eye Primates have evolved their eye morphologies to maximize their visual morphologies to maximize their visual sensitivity, in order to adapt to the activity sensitivity, in order to adapt to the activity patternspatterns