How does the crab-eating frog see?
The crab-eating frog (Fejervarya cancrivora) is a amphibian in the order Anura. Its eyes belong to the vision type Amphibian motion detector.
Measured in this species: colour and night vision. Measured colour or sharpness: a measured receptor set or acuity in this species; other dials come from relatives or group defaults. 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 2.8 cycles per degree: the finest stripe pattern it can tell apart from grey.
- It stops seeing flicker at 16.9 Hz, against 60 Hz for people in this dataset, so fast motion looks choppier to it.[7][5]
- 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: 433 nm (VS/SWS (violet)), 502 nm (MWS (green)) measured in this species | Measured (not re-verified) | [1] |
| Sharpness | Acuity 2.8 cycles per degree median of 1 relatives in order Anura: Lithobates pipiens | Group default | [2] |
| Field of view | No value in the catalogue. | ||
| Sharp zones (foveas) | No value in the catalogue. | ||
| Night vision | Activity pattern nocturnal mode of 2 rows (of 2 rows): nocturnal | Measured (not re-verified) | [3][4] |
| Rods vs cones rod-dominated nocturnal -> rod-dominated; crepuscular / cathemeral / mixed -> mixed; diurnal -> cone-dominated | Derived | [3][4] | |
| Motion (flicker fusion) | Flicker fusion frequency 16.9 Hz median of 2 relatives in order Anura: Rhinella marina, Lithobates clamitans | Group default | [5][6] |
Related animals
- Northern leopard frog same vision type
- African clawed frog same vision type
- American bullfrog same vision type
- Asiatic toad same vision type
- Bufo toad same vision type
- Common frog same vision type
More amphibians: all amphibians with measured vision data.
Sources
- Murphy MJ, Westerman EL. 2022. Evolutionary history limits species' ability to match colour sensitivity to available habitat light. Proc R Soc B 289:20220612. Electronic supplementary Table S1. doi.org/10.1098/rspb.2022.0612
- 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
- Anderson SR, Wiens JJ. 2017. Out of the dark: 350 million years of conservatism and evolution in diel activity patterns in vertebrates. Evolution 71:1944-1959. Dryad doi:10.5061/dryad.fg700. doi.org/10.5061/dryad.fg700
- 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
- 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
- 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
Every value cites its sources (all sources). Data: catalogue-v1, built 2026-09-29. Accuracy notes: how accurate is this?