How does the northern tree shrew see?
The northern tree shrew (Tupaia belangeri) is a mammal in the order Scandentia. Its eyes belong to the vision type Day dichromat mammal.
Measured in this species: colour, sharpness, 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 2.1 cycles per degree: the finest stripe pattern it can tell apart from grey.
- Its eyes cover about 250° around the head, with 60° seen by both eyes at once.
- It stops seeing flicker at 60 Hz, against 60 Hz for people in this dataset, so fast motion looks about the same.[12][11]
- Activity pattern: diurnal.
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: 444 nm (SWS (blue)), 556 nm (LWS (long)) species-v1.csv value measured in this species (not in tidy tables) | Measured (not re-verified) | [1] |
| Sharpness | Acuity 2.1 cycles per degree median of 2 behavioural rows (method priority rule) | Measured | [2][3] |
| Field of view | Binocular overlap 60° median of 1 relatives in genus Tupaia: Tupaia glis | Estimated | [4] |
| Total field of view 250° group default: median total field of vision type V02 within phylum Chordata in species-v1: Canis familiaris | Group default | [5] | |
| Sharp zones (foveas) | Number of foveas 0 median of 1 relatives in genus Tupaia: Tupaia glis | Estimated | [6] |
| Fovea type area centralis, horizontal streak | Estimated | [6] | |
| Night vision | Activity pattern diurnal mode of 4 rows (of 4 rows): diurnal | Measured (not re-verified) | [7][8][9][10] |
| Rods vs cones cone-dominated nocturnal -> rod-dominated; crepuscular / cathemeral / mixed -> mixed; diurnal -> cone-dominated | Derived | [7][8][9][10] | |
| Motion (flicker fusion) | Flicker fusion frequency 60 Hz median of 1 bright-light rows (behavioural/whole-eye ERG rows; all rows: [60.0]) | Measured | [11] |
Related animals
- Dog same vision type
- Grey wolf same vision type
- Bolivian squirrel monkey same vision type
- Bushbaby same vision type
- Common marmoset same vision type
- Fat-tailed dwarf lemur same vision type
More mammals: all mammals with measured vision data.
Sources
- species_v1:Jacobs & Neitz 1986
- Caves EM, Fernandez-Juricic E, Kelley LA (2024) Ecological and morphological correlates of visual acuity in birds. J Exp Biol 227(2): jeb246063. Supplementary Table S1.. doi.org/10.1242/jeb.246063
- 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
- Heesy CP 2004. On the relationship between orbit orientation and binocular visual field overlap in mammals. Anat Rec 281A:1104, Table 1. doi.org/10.1002/ar.a.20116
- species_v1:Miller & Murphy 1995
- 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
- 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
- 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
- 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
- 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
- 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
Every value cites its sources (all sources). Data: catalogue-v1, built 2026-09-29. Accuracy notes: how accurate is this?