How does the brown rat see?
The brown rat (Rattus norvegicus) is a mammal in the order Rodentia. Its eyes belong to the vision type Small prey mammal (UV): 2-3 cones often incl. UV (mouse, rat, hamster, dunnart), very low acuity, near-panoramic field.
Measured in this species: colour, sharpness, field of view, foveas, night vision and motion (flicker fusion). Measured core: measured values on at least 3 of the 6 dials. Every value below carries its evidence level and sources; nothing is typed by hand.
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What stands out
- It has two colour receptor classes (a dichromat): reds and greens fall on one axis, as in red-green colour blindness in people.
- Its sharpest vision resolves 1.5 cycles per degree: the finest stripe pattern it can tell apart from grey.
- Both eyes see the same 55.5° in front of it (binocular overlap), where depth is judged best.
- It stops seeing flicker at 51 Hz, against 60 Hz for people in this dataset, so fast motion looks choppier to it.[14][15]
- Activity pattern: nocturnal.
The six dials
Evidence levels: how the tiers work. "Measured" means a value measured in this species; "Estimated" values come from a close relative or an eye-size formula.
| Dial | Value | Evidence | Sources |
|---|---|---|---|
| Colour | Colour receptors 2 receptor classes: 358 nm (UVS), 509 nm (MWS (green)) measured in this species | Measured | [1] |
| Ultraviolet yes: at least one receptor peaks in the ultraviolet | Measured | ||
| Sharpness | Acuity 1.5 cycles per degree median of 2 behavioural rows (method priority rule) | Measured | [2][3] |
| Field of view | Binocular overlap 55.5° median of 1 rows (eyes-at-rest rows preferred) | Measured | [4] |
| Eye placement lateral frontal if binocular overlap >= 60 deg, else lateral | Derived | [4] | |
| Sharp zones (foveas) | Number of foveas 0 fovea_present / area_centralis_type (retinal topography; count 1 = fovea present, 0 = none) | Measured | [5] |
| Fovea type horizontal streak | Measured | [5] | |
| Night vision | Activity pattern nocturnal mode of 6 rows (of 6 rows): cathemeral; nocturnal; scotopic | Measured (not re-verified) | [6][7][8][9][10][3] |
| Pupil shape circular | Group default | [11] | |
| Reflective layer (tapetum) no | Measured | [12] | |
| Rods vs cones rod-dominated nocturnal -> rod-dominated; crepuscular / cathemeral / mixed -> mixed; diurnal -> cone-dominated | Derived | [6][7][8][9][10][3] | |
| Motion (flicker fusion) | Flicker fusion frequency 51 Hz median of 1 bright-light rows (behavioural/whole-eye ERG rows; all rows: [51.0]); cff_hz: dim-light rows (bright-light rows used) set aside (labelled alternative: 21.6, 25.0, 39.0, 42.0, 43.0, 47.0) | Measured | [13] |
Related animals
- House mouse same vision type
- Mongolian jird same vision type
- Syrian hamster same vision type
- Daurian ground squirrel same vision type
- Degu same vision type
- Grey squirrel same vision type
More mammals: all mammals with measured vision data.
Sources
- Frazer SA, Baghalian M, et al. 2024. Discovering genotype-phenotype relationships with machine learning and the Visual Physiology Opsin Database (VPOD). GigaScience 13:giae073; VPOD v1.3 data release. doi.org/10.5281/zenodo.19051998
- Kirk EC, Kay RF 2004. The evolution of high visual acuity in the Anthropoidea. In Anthropoid Origins, Table 1 (behavioural acuity). doi.org/10.1007/978-1-4419-8873-7_20
- Veilleux CC, Kirk EC 2014. Visual acuity in mammals. Brain Behav Evol 83:43, Supplementary Table 1 (cleaned CSV in Evo-M1-Trait-Data). doi.org/10.1159/000357830
- Heffner RS, Heffner HE 1992. Visual factors in sound localization in mammals. J Comp Neurol 317:219, Table 1 (via Evo-M1 sensory merge). doi.org/10.1002/cne.903170302
- Kopania EEK, Clark NL. 2025. Mammalian retinal specializations for high acuity vision evolve in response to both foraging strategies and morphological constraints. Evolution Letters 9: qrae072. Supplementary Tables S1-S2.. doi.org/10.1093/evlett/qrae072
- Borges R, Johnson WE, O'Brien SJ, Gomes C, Heesy CP, Antunes A (2018) Adaptive genomic evolution of opsins reveals that early mammals flourished in nocturnal environments. BMC Genomics 19:121
- Wilman et al. 2014 EltonTraits 1.0, MamFuncDat.txt. doi.org/10.6084/m9.figshare.3559887.v1
- Maor R, Dayan T, Ferguson-Gow H, Jones KE. 2017. Temporal niche expansion in mammals from a nocturnal ancestor after dinosaur extinction. Nature Ecology & Evolution 1:1889-1895. Supplementary Table 1. doi.org/10.1038/s41559-017-0366-5
- Schmitz L, Motani R. 2011. Science 332:705-708, SOM. doi.org/10.1126/science.1200043
- Moura et al. 2024. A phylogeny-informed characterisation of global tetrapod traits addresses data gaps and biases. PLoS Biol 22:e3002658. TetrapodTraits v3.0.1.. doi.org/10.5281/zenodo.22536349
- Banks MS, Sprague WW, Schmoll J, Parnell JAQ, Love GD. 2015. Science Advances 1:e1500391. doi.org/10.1126/sciadv.1500391
- Dunn D, Baker J, Sorden S. 2017. Eye and Associated Glands Boorman's Pathology of the Rat :251-278. europepmc.org/article/PMC/PMC7148627
- Lafitte A, Sordello R, Legrand M, Nicolas V, Obein G, Reyjol Y. 2022. A flashing light may not be that flashy: A systematic review on critical fusion frequencies. PLoS ONE 17(12): e0279718. S10 File (CFF database). doi.org/10.1371/journal.pone.0279718
- Healy K, McNally L, Ruxton GD, Cooper N, Jackson AL. 2013. Metabolic rate and body size are linked with perception of temporal information. Animal Behaviour 86:685-696. Table 1. doi.org/10.1016/j.anbehav.2013.06.018
- Inger R, Bennie J, Davies TW, Gaston KJ. 2014. Potential biological and ecological effects of flickering artificial light. PLoS ONE 9(5): e98631. Table 3. doi.org/10.1371/journal.pone.0098631
Every value cites its sources (all sources). Data: catalogue-v1, built 2026-09-29. Accuracy notes: how accurate is this?