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How does the west Indian manatee see?

The west Indian manatee (Trichechus manatus) is a mammal in the order Sirenia. Its eyes belong to the vision type Small prey mammal (UV).

Measured in this species: colour, foveas and night vision. 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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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.

Vision values for the west Indian manatee (Trichechus manatus), catalogue-v1
DialValueEvidenceSources
ColourColour receptors
2 receptor classes: 411 nm (VS/SWS (violet)), 543 nm (LWS (long))
measured in this species
Measured (not re-verified)[1][2][3]
SharpnessAcuity
17.08 cycles per degree
allometry (Mammalia): log10(acuity_cpd) = intercept + slope * log10(eye_axial_length_mm); slope 1.2182, intercept -0.6097, R2 0.45, n 72 (fitted in this script; fitted range [1.9, 48.147] mm); eye_axial_length_mm…
Estimated[4]
Field of viewBinocular overlap
75°
median of 41 relatives in class Mammalia: Octodon degus, Octodon lunatus, Equus caballus, Ovis aries, Bos taurus, Capra hircus
Group default[5][6][7][8]
Sharp zones (foveas)Number of foveas
0
fovea_present / area_centralis_type (retinal topography; count 1 = fovea present, 0 = none)
Measured[9]
Fovea type
none		Measured[9]
Night visionActivity pattern
cathemeral
mode of 4 rows (of 6 rows): aquatic; arrhythmic/cathemeral; cathemeral; mixed (nocturnal/crepuscular, cathemeral, crepuscular or diurnal/crepuscular)
Measured (not re-verified)[10][11][12][13][14][15]
Rods vs cones
mixed
nocturnal -> rod-dominated; crepuscular / cathemeral / mixed -> mixed; diurnal -> cone-dominated
Derived[10][11][12][13][14][15]
Motion (flicker fusion)Flicker fusion frequency
60 Hz
median of 21 relatives in class Mammalia: Rattus norvegicus, Cavia porcellus, Mus musculus, Felis catus, Macaca mulatta, Macaca nemestrina
Group default[16][17][18][19]

Related animals

More mammals: all mammals with measured vision data.

Sources

  1. 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
  2. Longcore T. 2023. A compendium of photopigment peak sensitivities and visual spectral response curves of terrestrial wildlife to guide design of outdoor nighttime lighting. Basic Appl Ecol 73:40-50. doi:10.1016/j.baae.2023.09.002. doi.org/10.5281/zenodo.8432720
  3. 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
  4. 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
  5. 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
  6. 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
  7. Vega-Zuniga T, Medina FS, Fredes F, et al. 2013. Does nocturnality drive binocular vision? Octodontine rodents as a case study. PLoS ONE 8: e84199.. doi.org/10.1371/journal.pone.0084199
  8. Vega-Zuniga T, Medina FS, Marín G, Letelier JC, Palacios AG, Němec P, Schleich CE, Mpodozis J. (2017). Selective binocular vision loss in two subterranean caviomorph rodents: Spalacopus cyanus and Ctenomys talarum. Scientific reports
  9. 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
  10. 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
  11. 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
  12. Wilman et al. 2014 EltonTraits 1.0, MamFuncDat.txt. doi.org/10.6084/m9.figshare.3559887.v1
  13. 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
  14. Jones KE et al. 2009. PanTHERIA: a species-level database of life history, ecology, and geography of extant and recently extinct mammals. Ecology 90:2648. Ecological Archives E090-184. doi.org/10.1890/08-1494.1
  15. 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
  16. Haarlem CS, Hynes C, Jackson AL, Mitchell KJ, O'Connell RG, Healy K. 2026. Pace of ecology drives the tempo of visual perception across the animal kingdom. Nature Ecology & Evolution (doi:10.1038/s41559-026-02994-7). Figshare dataset 10.6084/m9.figshare.30556475. doi.org/10.6084/m9.figshare.30556475
  17. 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
  18. 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
  19. 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

Every value cites its sources (all sources). Data: catalogue-v1, built 2026-09-29. Accuracy notes: how accurate is this?