Little is known about the visual systems of large baleen whales (Mysticeti: Cetacea). In this study, we investigate eye morphology and the topographic distribution of retinal ganglion cells (RGCs) in two species of mysticete, Bryde’s whale (Balaenoptera edeni) and the humpback whale (Megaptera novaeanglia). Both species have large eyes characterised by a thickened cornea, a heavily thickened sclera, a highly vascularised fibro-adipose bundle surrounding the optic nerve at the back of the eye, and a reflective blue-green tapetum fibrosum. Using stereology and retinal whole mounts, we estimate a total of 274,268 and 161,371 RGCs in the Bryde’s whale and humpback whale retinas, respectively. Both species have a similar retinal topography, consisting of nasal and temporal areas of high RGC density, suggesting that having higher visual acuity in the anterior and latero-caudal visual fields is particularly important in these animals. The temporal area is larger in both species and contains the peak RGC densities (160 cells mm–2 in the humpback whale and 200 cells mm–2 in Bryde’s whale). In the Bryde’s whale retina, the two high-density areas are connected by a weak centro-ventral visual streak, but such a specialisation is not evident in the humpback whale. Measurements of RGC soma area reveal that although the RGCs in both species vary substantially in size, RGC soma area is inversely proportional to RGC density, with cells in the nasal and temporal high-density areas being relatively more homogeneous in size compared to the RGCs in the central retina and the dorsal and ventral retinal periphery. Some of the RGCs were very large, with soma areas of over 2,000 µm2. Using peak RGC density and eye axial diameter (Bryde’s whale: 63.5 mm; humpback whale: 48.5 mm), we estimated the peak anatomical spatial resolving power in water to be 4.8 cycles/degree and 3.3 cycles/degree in the Bryde’s whale and the humpback whale, respectively. Overall, our findings for these two species are very similar to those reported for other species of cetaceans. This indicates that, irrespective of the significant differences in body size and shape, behavioural ecology and feeding strategy between mysticetes and odontocetes (toothed whales), cetacean eyes are adapted to vision in dim light and adhere to a common “bauplan” that evolved prior to the divergence of the two cetacean parvorders (Odontoceti and Mysticeti) over 30 million years ago.

Keywords:
Bryde’s whale, Cetacean, Eye, Humpback whale, Retinal ganglion cell, Retinal whole mount, Tapetum, Visual ecology
1.
Ahnelt PK, Schubert C, Kübber-Heiss A, Schiviz A, Anger E (2006): Independent variation of retinal S and M cone photoreceptor topographies: a survey of four families of mammals. Vis Neurosci 23: 429–435.
2.
Au WWL (2009): Echolocation; in Perrin WF, Würsig B, Thewissen JGM (eds): Encyclopedia of Marine Mammals, ed 2. Amsterdam, Academic Press, pp 348–357.
3.
Bannister JL (2009): Baleen whales (mysticetes); in Perrin WF, Würsig B, Thewissen JGM (eds): Encyclopedia of Marine Mammals, ed 2. Amsterdam, Academic Press, pp 80–89.
4.
Berta A, Ekdale EG, Zellmer NT, Demére TA, Kienle SS, Smallcomb M (2015): Eye, nose, hair and throat: external anatomy of the head of a neonate gray whale (Cetacea, Mysticeti, Eschrichtiidae). Anat Rec 298: 648–659.
5.
Bjerager P, Heegaard S, Tougaard J (2003): Anatomy of the eye of the sperm whale (Physeter macrocephalus L.). Aquat Mam 29: 31–36.
6.
Buono MR, Fernandez MS, Herrera Y (2012): Morphology of the eye of the southern right whales (Eubalaena australis). Anat Rec 295: 355–368.
7.
Caves EM, Sutton TT, Johnsen S (2017): Visual acuity in ray-finned fishes correlates with eye size and habitat. J Exp Biol 220: 1586–1596.
8.
Clapham PJ (2009): Humpback whale Megaptera novaeangliae; in Perrin WF, Würsig B, The-wissen JGM (eds): Encyclopedia of Marine Mammals, ed 2. Amsterdam, Academic Press, pp 582–585.
9.
Clapham PJ, Baker CS (2009): Whaling, modern; in Perrin WF, Würsig B, Thewissen JGM (eds): Encyclopedia of Marine Mammals, ed 2. Amsterdam, Academic Press, pp 1239–1243.
10.
Coimbra JP, Bertelsen MF, Manger PR (2017): Retinal ganglion cell topography and spatial resolving power in the river hippopotamus Hippopotamus amphibious. J Comp Neurol 525: 2499–2513.
11.
Coimbra JP, Hart NS, Collin SP, Manger PR (2013): Scene from above: retinal ganglion cell topography and spatial resolving power in the giraffe (Giraffa camelopardalis). J Comp Neurol 521: 2042–2057.
12.
Coimbra JP, Manger PR (2017): Retinal ganglion cell topography and spatial resolving power in the white rhinoceros (Ceratotherium simum). J Comp Neurol 525: 2484–2498.
13.
Coimbra JP, Marceliano MLV, da Andrade-Da-Costa BLS, Yamada ES (2006): The retina of tyrant flycatchers: topographic organization of neuronal density and size in the ganglion cell layer of the great kiskadee Pitangus sulphuratus and the rusty margined flycatcher Myiozetetes cayanensis (Aves: Tyrannidae). Brain Behav Evol 68: 15–25.
14.
Coimbra JP, Nolan PM, Collin SP, Hart NS (2012): Retinal ganglion cell topography and spatial resolving power in penguins. Brain Behav Evol 80: 254–268.
15.
Coimbra JP, Trévia N, Marceliano ML, da Silveira Andrade-da-Costa BL, Picanço-Diniz CW, Yamada ES (2009): Number and distribution of neurons in the retinal ganglion cell layer in relation to foraging behaviors of tyrant flycatchers. J Comp Neurol 514: 66–73.
16.
Collin SP (1999): Behavioural ecology and retinal cell topography; in Archer SN, Djamgoz MBA, Loew ER, Partridge JC, Vallerga S (eds): Adaptive Mechanisms in the Ecology of Vision. New York, Springer Science+Business Media, pp 509–535.
17.
Collin SP, Pettigrew JD (1989): Quantitative comparison of the limits on visual spatial resolution set by the ganglion cell layer in twelve species of reef teleosts. Brain Behav Evol 34: 184–192.
18.
Committee on Taxonomy (2017): List of marine mammal species and subspecies. Society for Marine Mammalogy. https://www.marinemammalscience.org (accessed April 12, 2018).
19.
Cronin TW, Fasick JI, Schweikert LE, Johnsen S, Kezmoh LJ, Baumgartner MF (2017): Coping with copepods: do right whales (Eubalaena glacialis) forage visually in dark waters? Phil Trans R Soc Lond B 372: 20160067.
20.
Dawson WW (1980): The cetacean eye; in Herman LM (ed): Cetacean Behavior: Mechanisms and Functions. Hoboken, Wiley, pp 51–100.
21.
Dawson WW, Hawthorne MN, Jenkins RL, Goldston RT (1982): Giant neural system in the inner retina and optic nerve of small whales. J Comp Neurol 205: 1–7.
22.
Dral ADG (1983): The retinal ganglion cells of Delphinus delphis and their distribution. Aquat Mam 10: 57–68.
23.
Dral ADG (1987): On the optics of the dolphin eye. Aquat Mam 13: 61–64.
24.
Friedlaender AS, Hazen EL, Nowacel DP, Halpin PN, Ware C, Weinrich MT, Hurst T, Wiley D (2009): Diel changes in humpback whale Megaptera novaeangliae feeding behavior in response to sand lance Ammodytes spp. behavior and distribution. Mar Ecol Prog Ser 395: 91–100.
25.
Fritsches KA, Marshall NJ, Warrant EJ (2003): Retinal specializations in the blue marlin: eyes designed for sensitivity to low light levels. Mar Freshw Res 54: 333–341.
26.
Gao A, Zhou K (1987): On the retinal ganglion cells of Neophocaena and Lipotes. Acta Zool Sinica 33: 316–332.
27.
Goldbogen JA, Friedlaender AS, Calambokidis J, McKenna MF, Simon M, Nowacek DP (2013): Integrative approaches to the study of baleen whale diving behaviour, feeding performance, and foraging ecology. BioScience 63: 90–100.
28.
Goldbogen JA, Pyenson ND, Shadwick RE (2007): Big gulps require high drag for fin whale lunge feeding. Mar Ecol Prog Ser 349: 289–301.
29.
Greenland JA, Limpus CJ (2006): Marine wildlife stranding and mortality database annual report, 2005. II. Cetaceans and pinnipeds. Conversation Technical and Data Report 2005: 1–40.
30.
Gundersen HJG (1977): Notes on the estimation of the numerical density of arbitrary particles: the edge effect. J Microsc 111: 219–223.
31.
Haines JA, Limpus CJ (2001): Marine wildlife stranding and mortality database annual report, 2000. II. Cetaceans and pinnipeds. Research Coordination Unit, Parks and Wildlife Strategy Division, Queensland Parks and Wildlife.
32.
Hanke FD, Peichl L, Dehnhardt G (2009): Retinal ganglion cell topography in juvenile harbor seals (Phoca vitulina). Brain Behav Evol 74: 102–109.
33.
Harman A, Dann J, Ahmat A, Macuda T, Johnston K, Timney B (2001): The retinal ganglion cell layer and visual acuity of the camel. Brain Behav Evol 58: 15–27.
34.
Herman LM (1990): Cognitive performance of dolphins in visually-guided tasks; in Thomas JA, Kastelein (eds): Sensory Abilities of Cetaceans: Laboratory and Field Evidence. New York, Springer Science+Business Media, pp 455–462.
35.
Herman LM (2010): What laboratory research has told us about dolphin cognition. Int J Comp Psychol 23: 310–330.
36.
Herman LM, Peacock MF, Yunker MP, Madsen CJ (1975): Bottlenose dolphin: double-slit pupil yields equivalent aerial and underwater diurnal acuity. Science 189: 650–652.
37.
Hooker SK (2009): Toothed whales, overview; in Perrin WF, Würsig B, Thewissen JGM (eds): Encyclopedia of Marine Mammals, ed 2. Amsterdam, Academic Press, pp 1173–1179.
38.
Howland HC, Merola S, Basarab JR (2004): The allometry and scaling of the size of vertebrate eyes. Vision Res 44: 2043–2065.
39.
Hughes A (1977): The topography of vision in mammals of contrasting life style: comparative optics and retinal organisation; in Cre-scitelli F (ed): Handbook of Sensory Physiology. The Visual System of Vertebrates. Berlin, Spinger, vol VII/5, pp 613–756.
40.
Hughes A (1985): New perspectives in retinal organisation. Prog Retinal Res 4: 243–313.
41.
International Whaling Commission (2008): Report of the scientific committee. J Cetac Res Manage 10(suppl): 1–406.
42.
Jefferson TA, Leatherwood S, Webber MA (1993): FAO Species Identification Guide. Marine Mammals of the World. Rome, Food and Agriculture Organization of the United Nations.
43.
Kassab A, Sugita S (2000): Study of ganglion cell topography of the retina in buffaloes (Bos bubalis). Anim Sci J 71: 600–608.
44.
Kato H, Perrin WF (2009): Bryde’s whales Balaenoptera edeni/brydei; in Perrin WF, Würsig B, Thewissen JGM (eds): Encyclopedia of Marine Mammals, ed 2. Amsterdam, Academic Press, pp 158–163.
45.
Kershaw F, Leslie MS, Collins T, Mansur RM, Smith BD, Minton G, Baldwin R, LeDuc RG, Anderson RC, Brownell RL Jr, Rosenbaum HC (2013): Population differentiation of 2 forms of Bryde’s whales in the Indian and Pacific Oceans. J Hered 104: 755–764.
46.
Kiltie RA (2000): Scaling of visual acuity with body size in mammals and birds. Funct Ecol 14: 226–234.
47.
Kröger RHH, Katzir G (2008): Comparative anatomy and physiology of vision in aquatic tetrapods; in Thewissen JGM, Nummela S (eds): Sensory Evolution on the Threshold. Berkeley, University of California Press, pp 121–147.
48.
Kröger RHH, Kirschfeld K (1994): Refractive index in the cornea of a harbour porpoise (Phocoena phocoena) measured by two-wavelengths laser-interferometry. Aquat Mam 20: 99–107.
49.
Kuhrt H, Bringmann A, Härtig W, Wibbelt G, Peichl L, Reichenbach A (2017): The retina of Asian and African elephants: comparison of newborn and adult. Brain Behav Evol 89: 84–103.
50.
Land MF, Nilsson DE (2012): Animal Eyes, ed 2. Oxford, Oxford University Press.
51.
Lisney TJ, Collin SP (2008): Retinal ganglion cell distribution and spatial resolving power in elasmobranchs. Brain Behav Evol 72: 59–72.
52.
Lisney TJ, Iwaniuk AN, Bandet MV, Wylie DR (2012): Eye shape and retinal topography in owls (Aves: Strigiformes). Brain Behav Evol 79: 218–236.
53.
Lisney TJ, Stecyk K, Kolominsky J, Schmidt BK, Corfield JR, Iwaniuk AN, Wylie DW (2013a): Ecomorphology of eye shape and retinal topography in waterfowl (Aves: Anseriformes: Anatidae) with different foraging modes. J Comp Physiol A 199: 385–402.
54.
Lisney TJ, Stecyk K, Kolominsky J, Schmidt BK, Corfield JR, Iwaniuk AN, Wylie DW (2013b): Comparison of eye morphology and retinal topography in two species of new world vultures (Aves: Cathartidae). Anat Rec 296: 1954–1970.
55.
Lisney TJ, Wylie DW, Kolominsky J, Iwaniuk AN (2015): Eye morphology and retinal topography in hummingbirds (Trochilidae: Aves). Brain Behav Evol 86: 176–190.
56.
Luksenburg JA, Henriquez A, Sangster G (2015): Molecular and morphological evidence for the subspecifc identity of Bryde’s whales in the southern Caribbean. Mar Mam Sci 31: 1568–1579.
57.
Lythgoe JN (1979): The Ecology of Vision. Oxford, Oxford University Press.
58.
Malkemper RP, Peichl L (2018): Retinal photoreceptor and ganglion cell types and topographies in the red fox (Vulpes vulpes) and Arctic fox (Vulpes lagopus). J Comp Neurol 526: 2078–2098.
59.
Mann J (2009): Parental behavior; in Perrin WF, Würsig B, Thewissen JGM (eds): Encyclopedia of Marine Mammals, ed 2. Amsterdam, Academic Press, pp 830–835.
60.
Mann J, Connor, RC, Tyack PL, Whitehead H (2000): Cetacean Societies: Field Studies of Dolphins and Whales. Chicago, University of Chicago Press.
61.
Mass AM, Supin AY, Severtsov AN (1986): Topographic distribution of size and density of ganglion cells in the retina of a porpoise, Phocoena phocoena. Aquat Mam 12: 95–102.
62.
Mass AM, Supin AY (1989): Distribution of ganglion cells in the retina of an amazon river dolphin Inia geoffrensis. Aquat Mam 15: 49–56.
63.
Mass AM, Supin AY (1995): Ganglion cell topography of the retina in the bottlenosed dolphin, Tursiops truncates. Brain Behav Evol 45: 257–265.
64.
Mass AM, Supin AY (1997): Ocular anatomy, retinal ganglion cell distribution, and visual resolution in the gray whale, Eschrichtius gibbosus. Aquat Mam 23: 17–28.
65.
Mass AM, Supin AY (1999): Retinal topography and visual acuity in the riverine tucuxi (Sotalia fluviatilis). Mar Mam Sci 15: 351–365.
66.
Mass AM, Supin AY (2002): Visual field organization and retinal resolution of the beluga, Delphinapterus leucas (Pallas). Aquat Mam 28: 241–250.
67.
Mass AM, Supin AY (2003): Retinal topography of the harp seal Pagophilus groenlandicus. Brain Behav Evol 62: 212–222.
68.
Mass AM, Supin AY (2007): Adaptive features of aquatic mammal’s eye. Anat Rec 290: 701–715.
69.
Mass AM, Supin AY (2009): Vision; in Perrin WF, Würsig B, Thewissen JGM (eds): Encyclopedia of Marine Mammals, ed 2. Amsterdam, Academic Press, pp 1200–1211.
70.
Mass AM, Supin AY (2010): Retinal ganglion cell layer of the Caspian seal Pusa caspica: topography and localization of the high-resolution area. Brain Behav Evol 76: 144–153.
71.
Mass AM, Supin AY (2016): Retinal ganglion cell topography and retinal resolution in the Baikal seal (Pusa sibirica). Brain Behav Evol 88: 59–67.
72.
Mass AM, Supin AY, Abramov AV, Mukhametov LM, Rozanova EI (2013): Ocular anatomy, ganglion cell distribution and retinal resolution of a killer whale (Orcinus orca). Brain Behav Evol 81: 1–11.
73.
Mazzatenta A, Caleo M, Baldaccini NE, Maffei L (2001): A comparative morphometric analysis of the optic nerve in two cetacean species, the striped dolphin (Stenella coeruleoalba) and fin whale (Balaenoptera physalus). Vis Neurosci 18: 319–325.
74.
McGowen MR, Gatesy J, Wildman DE (2014): Molecular evolution tracks macroevolutionary transitions in Cetacea. Trends Ecol Evol 29: 336–346.
75.
McGowen MR, Spaulding M, Gatesy J (2009): Divergence date estimation and a comprehensive molecular tree of extant cetaceans. Mol Phylo Evol 53: 891–906.
76.
Mengual R, García M, Segovia Y, Pertusa JF (2015): Ocular morphology, topography of ganglion cell distribution and visual resolution of the pilot whale (Globicephala melas). Zoomorphology 134: 339–349.
77.
Meredith RW, Gatesy J, Emerling CA, York VM, Springer MS (2013): Rod monochromacy and the coevolution of cetacean retinal opsins. PLoS Genet 9:e1003432.
78.
Miller S, Samuelson D, Dubielzig R (2013): Anatomic features of the cetacean globe. Vet Ophthalmol 16(suppl 1): 52–63.
79.
Mobley JR Jr, Helweg DA (1990): Visual ecology and cognition in cetaceans; in Thomas JA, Kastelein RA (eds): Sensory Abilities of Cetaceans: Laboratory and Field Evidence. New York, Springer Science+Business Media, pp 519–536.
80.
Montgelard C, Catzeflis FM, Douzery E (1997): Phylogenetic relationships of artiodactyls and cetaceans as deduced from the comparison of cytochrome b and 12S rRNA mitochondrial sequences. Mol Biol Evol 14: 550–559.
81.
Murayama T, Somiya H (1998): Distribution of ganglion cells and object localizing ability in the retina of three cetaceans. Fish Sci 64: 27–30.
82.
Murayama T, Somiya H, Aoki I, Ishii T (1992): The distribution of ganglion cells in the retina and visual acuity of minke whale. Nippon Suissan Gakkaishi 58: 1057–1061.
83.
Murayama T, Somiya H, Aoki I, Ishii T (1995): Retinal ganglion cell size and distribution predict visual capabilities of Dall’s propoise. Mar Mam Sci 11: 136–149.
84.
Ninomiya H, Yoshida E (2007): Functional anatomy of the ocular circulatory system: vascular corrosion casts of the cetacean eye. Vet Ophthalmol 10: 231–238.
85.
Oates DW, Coggin JL, Hartman FE, Hoilien GI (1984): A Guide to Time of Death in Selected Wildlife Species. Nebraska Technical Series No. 14. Lincoln, Nebraska Game & Parks Commission.
86.
Oyster CW, Takahashi ES, Hurst DC (1981): Density, soma size, and regional distribution of rabbit retinal ganglion cells. J Neurosci 1: 1331–1346.
87.
Peichl L (1991): Alpha ganglion cells in mammalian retinae: common properties, species differences, and some comments on other ganglion cells. Vis Neurosci 7: 155–169.
88.
Peichl L (1992): Topography of ganglion cells in the dog and wolf retina. J Comp Neurol 324: 603–620.
89.
Peichl L, Behrmann G, Kröger RHH (2001): For whales and seals the ocean is not blue: a visual pigment loss in marine mammals. Eur J Neurosci 13: 1520–1528.
90.
Perrin WF, Würsig B, Thewissen JGM (eds) (2009): Encyclopedia of Marine Mammals, ed 2. Amsterdam, Academic Press.
91.
Pettigrew JD, Bhagwandin A, Haagensen N, Manger PR (2010): Visual acuity and heterogeneities of retinal ganglion cell densities and the tapetum lucidum of the African elephant (Loxodonta africana). Brain Behav Evol 75: 251–261.
92.
Pettigrew JD, Dreher B, Hopkins CS, McCall MJ, Brown M (1988): Peak density and distribution of ganglion cells in the retinae of microchiropteran bats: implications for visual acuity. Brain Behav Evol 32: 39–56.
93.
Pettigrew JD, Manger PR (2008): Retinal ganglion cell density of the black rhinoceros (Diceros bicornis): calculating visual resolution. Vis Neurosci 25: 215–220.
94.
Pilleri G, Wandeler A (1964): Ontogeny and functional morphology of the eye of the fin whale Balaenoptera physalus Linnaeus (Cetacea, Mysticeti, Balaenopteridae). Acta Anat Suppl 50: 179–245.
95.
Quinn GP, Keough MJ (2002): Experimental Design and Data Analysis for Biologists. Cambridge, Cambridge University Press.
96.
Rivamonte LA (1976): Eye model to account for comparable aerial and underwater acuities of the bottlenose dolphin. Neth J Sea Res 10: 491–498.
97.
Rivamonte LA (2009): Bottlenose dolphin (Tursiops truncatus) double-slit pupil asymmetries enhance vision. Aquat Mam 35: 269–280.
98.
Rodrigues FM, Silva FMO, Trompieri-Silveira AC, Vergara-Parente JE, Miglino MA, Guimaraes JP (2014): Morphology of the eyeball from the humpback whale (Megaptera novaeangliae). Micros Res Tech 77: 348–355.
99.
Rose KD (2001): The ancestry of whales. Science 293: 2216–2217.
100.
Rosel PE, Wilcox LA (2014): Genetic evidence reveals a unique lineage of Bryde’s whales in the northern Gulf of Mexico. Endang Species Res 25: 19–34.
101.
Sanes JR, Masland RH (2015): The types of retinal ganglion cells: current status and implications for neuronal classification. Annu Rev Neurosci 38: 221–246.
102.
Schaeffer RL, Mendenhall W, Ott L (1996): Elementary Survey Sampling, ed 5. Boston, PWS-Kent.
103.
Schiviz AN, Ruf T, Kuebber-Heiss A, Schubert C, Ahnelt PK (2008): Retinal cone topography of artiodactyl mammals: influence of body height and habitat. J Comp Neurol 507: 1336–1350.
104.
Schmitz C, Hof PR (2000): Recommendations for straightforward and rigorous methods of counting neurons based on a computer simulation approach. J Chem Neuroant 20: 93–114.
105.
Schneider CA, Rasband WS, Eliceiri KW (2012): NIH Image to ImageJ: 25 years of image analysis. Nat Methods 9: 671–675.
106.
Schwab IR, Yuen CK, Buyukmihci NC, Blakenship TN, Fitzgerald PG (2002): Evolution of the tapetum. Trans Am Ophthalmol Soc 100: 187–200.
107.
Schweikert LE, Fasick JI, Grace MS (2016): Evolutionary loss of cone photoreception in balaenid whales reveals circuit stability in the mammalian retina. J Comp Neurol 524: 2873–2885.
108.
Shinozaki A, Takagi S, Hosaka YZ, Uehara M (2013): The fibrous tapetum of the horse eye. J Anat 223: 509–518.
109.
Širovic A, Bassett HR, Johnson SC, Wiggins SM, Hildebrand JA (2014): Bryde’s whale calls recorded in the Gulf of Mexico. Mar Mam Sci 30: 399–409.
110.
Snyder AW, Miller WH (1977): Photoreceptor diameter and spacing for highest spatial resolving power. J Opt Soc Am 67: 696–698.
111.
Spong P, White D (1971): Visual acuity and discrimination learning in the dolphin (Lagenorhynchus obliquidens). Exp Neurol 31: 431–436.
112.
Stimpert AK, Wiley DN, Au WWL, Johnson MP, Arsenault R (2007): “Megapclicks”: acoustic click trains and buzzes produced during night-time foraging of humpback whales (Megaptera novaeangliae). Bio Lett 3: 467–470.
113.
Stone J (1965): A quantitative analysis of the distribution of ganglion cells in the cat’s retina. J Comp Neurol 124: 337–352.
114.
Stone J (1981): The Whole Mount Handbook. A Guide to the Preparation and Analysis of Retinal Whole Mounts. Sydney, Maitland.
115.
Supin AY, Popov VV, Mass AM (2001): The Sensory Physiology of Aquatic Mammals. New York, Springer Science+Business Media.
116.
Thewissen JGM, Nummela S (2008): Sensory Evolution on the Threshold. Berkeley, University of California Press.
117.
Thomas PO, Reeves RR, Brownell RL Jr (2016): Status of the world’s baleen whales. Mar Mam Sci 32: 682–734.
118.
Timney B, Keil K (1992): Visual acuity in the horse. Vision Res 32: 2289–2293.
119.
Tomonaga M, Uwano Y, Saito T (2014): How dolphins see the world: a comparison with chimpanzees and humans. Sci Rep 4: 3717.
120.
Torres LG (2017): A sense of scale: foraging cetaceans’ use of scale-dependent multimodal sensory systems. Mar Mam Sci 33: 1170–1193.
121.
Walls GL (1942): The vertebrate eye and its adaptive radiation. Bloomfield Hills, Cranbrook Institute of Science.
122.
Wässle H (2004): Parallel processing in the mammalian retina. Nat Rev Neurosci 5: 747–757.
123.
West MJ (2012): Basic Stereology for Biologists and Neuroscientists. Cold Spring Harbor, Cold Spring Harbor Laboratory Press.
124.
West MJ, Slomianka L, Gundersen HJG (1991): Unbiased stereological estimation of the total number of neurons in the subdivisions of the rat hippocampus using the optical using the optical fractionator. Anat Rec 231: 482–497.
125.
White D, Cameron N, Spong P, Bradford J (1971): Visual acuity of the killer whale (Orcinus orca). Exp Neurol 32: 230–236.
126.
Williams DR, Coletta NJ (1987): Cone spacing and the visual resolution limit. J Opt Soc Am A 4: 1514–1523.
127.
Wiseman N, Enderby J, Enderby T (2007): Bryde’s whales in the Hauraki Gulf. New Zealand Geographic. https://www.nzgeo.com/stories/brydes-whales (accessed April 12, 2018).
128.
Woodward BL, Winn JP, Fish FE (2006): Morphological specializations of baleen whales associated with hydrodynamic performance and ecological niche. J Morph 267: 1284–1294.
129.
Würsig B, Kieckhefer T, Jefferson TA (1990): Visual displays for communication in cetaceans; in Thomas JA, Kastelein RA (eds): Sensory Abilities of Cetaceans: Laboratory and Field Evidence. New York, Springer Science+Busi-ness Media, pp 545–559.
130.
Würsig B, Whitehead H (2009): Aerial behavior; in Perrin WF, Würsig B, Thewissen JGM (eds): Encyclopedia of Marine Mammals, ed 2. Amsterdam, Academic Press, pp 5–11.
131.
Young NA, Hope GM, Dawson WW, Jenkins RL (1988): The tapetum fibrosum in the eyes of two small whales. Mar Mam Sci 4: 281–290.
132.
Zhou X, Xu S, Yang Y, Zhou K, Yang G (2011): Phylogenomic analyses and improved resolution of Cetartiodactyla. Mol Phylogenet Evol 61: 255–264.
133.
Zhu Q, Hillmann DJ, Henk WG (2001): Morphology of the eye and surrounding structures of the bowhead whale, Balaena mysticetus. Mar Mam Sci 17: 729–750.
134.
Zoidis AM, Lomac-MacNair KS (2017): A note on suckling behavior and laterality in nursing humpback whale calves from underwater observations. Animals (Basel) 7: 51.
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