How does the Pacific sanddab see?
The Pacific sanddab (Citharichthys sordidus) is a fish in the order Pleuronectiformes. Its eyes belong to the vision type Shallow-water fish tetrachromat.
Measured in this species: colour. 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 6.291 cycles per degree: the finest stripe pattern it can tell apart from grey.
- Both eyes see the same 32.85° in front of it (binocular overlap), where depth is judged best.
- It stops seeing flicker at 52 Hz, against 60 Hz for people in this dataset, so fast motion looks choppier to it.[10][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: 440 nm (SWS (blue)), 523 nm (MWS (green)) measured in this species | Measured | [1][2] |
| Sharpness | Acuity 6.291 cycles per degree allometry (Fishes (bony + jawless)): log10(acuity_cpd) = intercept + slope * log10(eye_diameter_mm); slope 0.7747, intercept 0.0533, R2 0.323, n 31 (fitted in this script; fitted range [2.5, 24.415] mm)… | Estimated | [3] |
| Field of view | Binocular overlap 32.85° group default: median of tier-A values in vision type V18 within phylum Chordata (2 species: Danio rerio, Notemigonus crysoleucas) | Group default | [4] |
| Sharp zones (foveas) | Number of foveas 0 group default: mode of tier-A values in vision type V18 within phylum Chordata (2 species: Toxotes jaculatrix, Anableps anableps) | Group default | [5][6] |
| Fovea type ventrotemporal area (high rgc density) | Group default | [5][6] | |
| Night vision | Activity pattern diurnal group default: mode of tier-A values in vision type V18 within phylum Chordata (224 species: Amphiprion ocellaris, Acanthochromis polyacanthus, Acanthurus bahianus, Acanthurus chirurgus, Acanthurus coeruleus… | Group default | [7][8] |
| Rods vs cones cone-dominated | Group default | [7][8] | |
| Motion (flicker fusion) | Flicker fusion frequency 52 Hz median of 1 relatives in family Paralichthyidae: Paralichthys dentatus | Estimated | [9] |
Related animals
- European plaice same vision type
- Slime flounder same vision type
- Bastard halibut same vision type
- Butter sole same vision type
- Common dab same vision type
- Crested flounder same vision type
More fish: all fish with measured vision data.
Sources
- Schweikert LE, Fitak RR, Caves EM, Sutton TT, Johnsen S. 2018. Spectral sensitivity in ray-finned fishes: diversity, ecology and shared descent. J Exp Biol 221:jeb189761. Table S1. doi.org/10.1242/jeb.189761
- VPOD in-vivo (MSP / single-cell) lambda max compendium, file scp_cleaned.csv, VPOD GitHub (Frazer et al. 2025 bioRxiv 10.1101/2025.08.22.671864). github.com/VisualPhysiologyDB/visual-physiology-opsin-db/tree/main/scripts_n_notebooks/vpod_ML_workflows/mine_n_match/data_sources/lmax/vpod
- Vertebrate eye-size compilation in Thomas et al. 2020 Dryad deposit (Thomas_vertebrates.csv). Primary sources: Howland et al. 2004 (n=313); Schmitz & Wainwright 2011 (n=265); Schmitz et al. 2013 (n=237); Hall 2008 (n=116); Veilleux & Kirk 2014 (n=91); Hall & Heesy 2011 (n=88); Liu et al. 2012 (n=66); Werner & Seifan 2006 (n=62); Lisney & Collin 2007 (n=46). doi.org/10.5061/dryad.1zcrjdfq7
- Pita D, Moore BA, Tyrrell LP, Fernandez-Juricic E. 2015. Vision in two cyprinid fish: implications for collective behavior. PeerJ 3:e1113.. doi.org/10.7717/peerj.1113
- species_v1:Schwab et al. 2001
- species_v1:Temple et al. 2010
- Froese R. & Pauly D. (eds). FishBase, snapshot v25.04 (morphmet, morphdat, species, families tables), distributed as parquet by C. Boettiger for rfishbase.. fishbase.org
- 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
- 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?