Retinal Specializations in Yellowtail Grunter Fish: A Biology Study

This assignment presents a comprehensive study of the retinal specializations in the Yellowtail grunter fish (Amniataba caudavittata). The research aimed to determine the total retinal area, estimate the total number of ganglion cells, and identify regions of high cell density. The methodology involved staining and microscopic analysis of the retina, with results showing a total retinal area of 2.38 cm2 and an estimated 56,000 ganglion cells. Photoreceptor measurements, including cone and rod dimensions, were also assessed. The findings highlight the fish's adaptation to light, with the discussion focusing on the role of ganglion cells in vision, photoreceptor distribution, and the implications of these retinal features for the fish's survival and behavior in its aquatic environment. The study concludes that the retinal structure of the Yellowtail grunter fish enables effective vision and adaptation to its habitat.

Retinal specializations in Yellowtail grunter Fish (Amniataba caudavittata)
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Retinal specializations in Yellowtail grunter Fish (Amniataba caudavittata)
Abstract
Introduction; Yellowtail grunter Fish species are commonly found in the coastal marines
and belong to the grunter family. Their morphology and adaptation have enabled it to
enhance and adapt to changes in the sea and to be able to have positive coexistence in the sea
environment. This fish has the ability to tolerate various environments. Light adaptation is of
key focus to this species. This study assessed the total retina area, the total number of
ganglion cells in the retina and determination of high cell density region in the retina.
Methods and materials; This study used yellowtail grunter fish species Amniataba
caudavittata), dissecting tools, microscope, buffer solution and camera in the retinal assessment. The
retinal assessment was undertaken using a stain buffer solution, dried and defatted to remove fat for
smooth staining then observed in the microscope. Images of various locations were obtained and the
ganglion cells observed using software image J. Results; The results showed that the total retina
area observed covered 2.38 cm2 with an estimated total of 56,000 ganglion cells. The clone
photoreceptor measurements showed an average of 0.0112 mm on double clone, single clone
length having a length to 0.0209 and single cone width of 0.0058mm. Rod assessment
showed an average of 0.0177 mm and width of 0.0009228, thus offering a high vision. High-
density region was observed on the dorsal lateral region of the eye. Discussion; The
observation of the retinal specialization of Amniataba caudavittata have shown to adapt to high
sensitivity towards light and adapt effectively in the environment which the fish inhabits. The retina
was observed to have a high concentration of gangrene cells which offers good adaption on vision
management. The specialization of Amniataba caudavittata retina offers a good avenue for effective
adaption of the fish in the water environment.

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1.0 Introduction
The yellow trumpeter- Amniataba caudavittata is a common species commonly found in
coastal marine species of the grunter family. The yellow trumpeter belongs to the common
species of the genius Amniataba among the grunter family. The growth mechanism of the
yellow trumpeter can grow with a maximum of the about of 28 cm long however the normal
size is 15 cm. The body is often compressed laterally with the first jaw being slightly longer
compared to the lower jaw. The first-gill arch has 6-8 gill rakers on the upper limb and 12-13
on the lower limb. The upper body has spots and is grey in color with light pigmentation.
Other types have incomplete vertical bars with either 5 or 6 which extend from the dorsal fin
to the pectoral fins. The fins have a characteristic color of yellow and varied dusting and
botch. The dorsal fins have irregular spotting and faint duskiness which do not exhibit any
distinct patch on dark pigmentation (Hilder et al., 2019).
These species have tolerance in salty habitats, fresh rivers, and hypersaline environments. It
often inhabits estuarine waters along with the Australian costs and the sand and seagrass beds
in inshore and offshore waters in the continental shelf’s. The Yellowtail trumpeter has been
observed to be a seasonal inhabitant in many estuaries in the shores of Western Australia with
the abundance of the species being observed in summer due to substantial juvenile recurrent
after the elapse of the spawning periods in the earlier summer. In the winter season, their
movements are characterized with deeper offshore locations so as to avoid larger freshwater
influxes entering the estuaries location from the upper locations. These species feed on the
algae, crustaceans, and polychaetes with dietary changes being observed with age (Smith &
Heemstra, 2012).
Their stay in the sea often limits their penetration to light. There is a need for deeper
adaptations in order to increase the sensitivity and extend the visual field of this species.
Assessment of retinal ganglion cells has often used to assess light exposure to fish in various
specific locations. Retinal ganglion cells refer to the inner surface of the retina which receives
the visual photoreceptor information through intermediate neuron types. The role of retinal
ganglion cells transmits images and nonimages through the formation of visual information
located in the retina in the form of the action potential to a various region of the brain. The
retinal ganglion cells often vary in size, connections, and responses it transmits. They have
long axon which aids in transmitting the information to the brain (Stenkamp, 2011).

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Retinal quantification of the ganglion cells has been undertaken. Their death often occurs
through apoptosis as observed in various models such as the optic nerve crunch, ischemia
among others. Its quantification is an essential aspect in order to assess its pathological
damage and pharmacological effects and its underlying protection and to better understand
the mechanism underlying the optic nerve and eye. Accurate quantification is essential so as
to determine these cell types in the retina and their regions of high density (Zou, Tian, Ge &
Hu, 2013).
The overall assessment of the ganglion cell and the general retinal area is critical in assessing
and understanding Yellowtail grunter Fish (Amniataba caudavittata) in water. Thus the aim
of this report sought to assess the total retains area, estimation on the total ganglion cells in
the whole retina and region of high cell concentration densities.
2.0 Materials and Methods
2.1 Materials
The following materials were required for this practical; three yellowtail grunter fish-
Amniataba caudavittata, dissecting kit, Petri dishes, microscope, buffered solution, and camera.
2.2 Methods
2.2.1 Staining the retina
The retina was fixed by putting a few drops of 4 % buffered formalin on top of the retina.
Then air drying followed on the heat block until color changes to a dull color. Further,
defatting process was undertaken on the retina to remove fat from the retina to enable tissue
to take up the stain, the dipping process was undertaken using the following time frame as
shown from table 1 below;
Table 1Staining procedure
2.2.2 Staining of the retina
with crystal violet
Chemical duration
70% alcohol 1 min
95% alcohol 1 min
100% alcohol 1 min
100% alcohol 1 min
Xylene 1 min
100% alcohol 1 min
95% alcohol 1 min
70% alcohol 1min

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Crystal violet was used to stain the retina in the following proportional and duration as
observed from table 2 below;
Table 2 Crystal violet retina staining
Chemical Duration
Water Few seconds
0.5% Crystal violet About 5 minutes
Water Several quick dips
Acetified 95% alcohol Few seconds
95% ordinary alcohol Few seconds
The level of staining was undertaken using a light microscope. The slides were observed in
the microscope with the retina dehydrated in the following ratios;
Table 3 Retina Dehydration
The retina was observed under the microscope and different images were selected at random.
The images were further analyzed and the ganglion cells observed and counted using
Software Image J.
3.0 Results
Ganglion cells
Total retina area calculated = 2.38 cm2. Out of the total 952 grids, each of 0.5 x 0.5 mm, 53
grids were sampled which turns out to be 5.57% of the total retina area. A total number of
ganglion cells counted in a sample are = 3193 cells.
Estimated total count = 56k ganglion cells
Chemical Duration
95% alcohol 1 min
100% alcohol 1 min
100% alcohol 1 min
First Xylene 5 min
Second Xylene 5 min

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Figure 1Ganglion Cell distribution
Photoreceptor measurements
Figure 2 Cone Photoreceptor overview
Scale : 0.01mm
Table 4 Photoreceptors assessments
Reference number DCW (mm) SCL (mm) SCW (mm)
1 0.011 0.019 0.006
2 0.012 0.019 0.005
3 0.011 0.023 0.006
4 0.012 0.021 0.006
5 0.010 0.021 0.004
6 0.011 0.023 0.006
7 0.010 0.021 0.006
8 0.012 0.021 0.006
9 0.012 0.020 0.007
10 0.011 0.021 0.006
Average 0.0112 mm 0.0209mm 0.0058mm
Key : DCW: Double Cone Width SCL: Single Cone Length SCW: Single cone Width;
Cones Scale: 0.01mm

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Rods Scale: 0.01mm
Figure 3 Rods photoreceptor assessment
Table 5 Rods photoreceptor length assessment
Reference number Length (mm) Width (mm)
1 0.018 0.001
2 0.018 0.000974
3 0.015 0.001
4 0.017 0.000761
5 0.019 0.001
6 0.018 0.000761
7 0.018 0.000819
8 0.017 0.001
9 0.022 0.001
10 0.015 0.000913
Average 0.0177 0.0009228 or 0.0009μm
4.0 Discussion
The ganglion cells were uniformly distributed across the retinal image phase as observed
from figure 1 above. The average cell density was 56 k ganglion cells obtained from the total
retina area a covered as 2.38 cm2. The topography distribution of the ganglion cells in the
retinal region did show any variation hence results reflecting the average number and size of
the retinal ear of the ganglion cells. The retina in fish often offers and provides high visual
sensitivity using low light conditions. The cone cells often provide spatial and temporal
resolutions and allow possible color differentiation. The rods often depend on fish ecology

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and differentiation. The overall distributing natures of the photoreceptors in the retina are not
always uniform. Some areas have been shown to have high densities than other regions
(Newman, Marshall & Collins, 2013). Fish can have two or more specialized species for high
acuity or sensitivity. The photoreceptor distribution often changes with time during the
development phase of the fish (Biagioni, Hunt & Collin, 2016). This is observed when the
fish moves from various region variation i.e shallow to deep water movements or changes in
the food spectrum and observed from the Antarctic ice fish. Other fish species such as
tapetum have reflective bouncing light effect in the retina and back again. This is essential in
enhancing sensitivity and low light conditions. The retinal appearance utilizes oxygen as
compared to other tissues and often has plentiful usage of oxygen. The vestibular ocular
reflex occurrence in the reflex eye movement offers stability during the head movement and
in a different direction. This aids in the image stabilization on the retina during tail
movement, (De Busserolles, Fitspatrcik, Marshall & Collin, 2014).
The general topography of the ganglion cells has often revealed that the location and peak of
cell density often reflect the habitat and visual axis of the fish. The study found out a total of
56,000 of ganglion cells in the retina chosen for the Yellowtail grunter Fish. This shows an
even distribution in the retinal area of the fish.
The photoreceptors photo measurements entail the single absorption and penetration in water.
The light is absorbed and scattered due to varying depth and intensity. The overall gradient
intensity reflects downward sunlight which is key in maintaining specific depth during the
day. The variation and adaptation of the light reflect visual adaptations to enhance detection
(Bailey et al., 2011). The adoption often increases relative to its eye size. The morphological
appearances of the retinal receptors among fish can be observed under maintenance selective
process among the species adapted to the light environment. Variation occurring in the
photoreceptor levels among the vertebrates often occurs among the subtypes and the overall
receptor size. Increase in the visual ability tends to achieve the high enlargement of the
photoreceptor absorption of the photon (Huang, Enzemann & Ildstad, 2011).
Topographic assessments of the photoreceptor identify key layers of key specialization in the
retina where there are high densities of the photoreceptor. These are essential in increasing
the sampling visual regions which are important on Yellowtail grunter Fish species. Cones
offer active levels of the light offering photocopy vision and differentiation of color. Three
types of cones occur with varying wavelengths. Yellowtail grunter Fish assessment on the
photoreceptor cones analysis showed that double cone width had an average of 0.0112 mm,
single clone length has 0.0209 mm and single cone width has 0.0058 length ion a scale of

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0.01mm.
Cones play a significant role in the vision assessment. They are less photo augmentable, have
fast response, less amplification time, none saturation response, selective directionality, lower
sensitivity, high acuity and chromatic levels (Alvarez-Delfin et al., 2009). This enables the
Yellowtail grunter Fish to have better vision and high photoreceptor properties. Like other
fish types, Yellowtail grunter Fish possess high specialization and adaptation of
photosensitivity which offers high pure rod retina and high photoreceptor offering a good
tune to the ambient light environment and the occurring light specificity. In most cases, fish
have double cones which are enjoined to each other. They have difference absorbance peak.
The different types of peak absorbance and behavior of fish are beneficial to the fish in the
water. The rods assessment showed an average length of 0.0177 mm and width of 0.0009228
mm. Rods in the retinal region offers vision ay scotopic vision state and mediate color vision
and the spatial acuity (Allison et al., 2011).
High-density regions of ganglion cells are often characterized by the different retinas
available. High region density is located at the dorsal temporal margin of the fish. The overall
assessment of the ganglion cell density is often characterized by the lateral cell displacements
in the fovea and occurrence of amacrine cells found in the ganglion layer. Yellowtail grunter
Fish assessment of the ganglion cells in the retina showed that increased density in the cones
assessment compared to the rods section region of the retina. This observed retinal
distribution occurring of the ganglion cells illustrates the visual abilities of the different
behavioral abilities and capabilities of the ecological vertebrates (Muguruma, Takei &
Yamamoto, 2013). (word count 854)
5.0 Conclusion
In conclusion, Retinal specializations in Yellowtail grunter Fish offers an in-depth assessment
of the overall adaptability of this species in water. The retinal assessment of fish plays a
significant factor in the overall process of enhancing adaptability in water. This report
focuses on three fundamental aspects. The total retinal area of Retinal specializations in
Yellowtail grunter Fish was found to be 2.38 cm2 with an estimate of 56, 000 ganglion cells.
The cells were evenly distributed in the retinal region of the eye. Shorter rod lengths were
observed in the retinal region and shorter length of cones was also observed. This is
beneficial for the accurate and high ability for photoreceptor ability for the Retinal
specializations in Yellowtail grunter Fish to adapt efficiently in water.

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