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Bonnethead vision: the science and the numbers

Sphyrna tiburo · order Carcharhiniformes · Sharks and rays: all the numbers

The bonnethead has one cone type, so no colour vision in daylight.[1] Its eyes cover about 338.3° with 13.4° seen by both eyes.[9] The bonnethead stops seeing flicker at 31 Hz, against 60 Hz for people.[25]

See it on your photoBack to How does the bonnethead see?
  • 1colour receptor classMeasured*
  • 338.3°field of viewMeasured
  • 31hertz flicker fusion (motion)Measured

The bonnethead (Sphyrna tiburo) is a shark or ray in the order Carcharhiniformes. Its eyes belong to the vision type Shark, ray and warm-eyed ocean predator: few cone types and a reflective layer for dim water. Measured in this species: colour, field of view and motion (flicker fusion). Measured colour or sharpness: a measured receptor set or acuity in this species; other dials come from relatives or group defaults.

This is a simulation built from published eye measurements, not what the animal experiences.

Method: How we know what animals see (the See Like Animals vision engine) · Sources · Last updated . Every value below carries its evidence level and sources; nothing is typed by hand.

What the bonnethead sees: colour receptors

Bonnethead colour receptor peaks, 300 to 700 nmBonnethead: 1 receptor peak at 483 nm; you: 3 at 421.5, 532, 558.4 nm. ultraviolet300400500600700
Bonnethead: 483 nmPeople: 421.5, 532, 558.4 nmWavelength in nanometres

What stands out

  • It has one receptor class for colour, so it sees brightness but no hue.
  • Its eyes cover about 338.3° around the head, with 13.4° seen by both eyes at once.
  • It stops seeing flicker at 31 Hz, against 60 Hz for people in this dataset, so fast motion looks choppier to it.[26][27]

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. The last column gives the values for people from the same catalogue.

Vision values for the bonnethead (Sphyrna tiburo), catalogue-v1
DialValueEvidenceSourcesPeople
ColourColour receptors
1 receptor class: 483 nm (MWS (green))
measured in this species
Measured (not re-verified)[1]Colour receptors: 3 receptor classes: 421.5 nm (VS/SWS (violet)), 532 nm (MWS (green)), 558.4 nm (LWS (long)) Measured (not re-verified)[2][3][4][5]
SharpnessAcuity
6.72 cycles per degree
median of 3 relatives in genus Sphyrna: Sphyrna lewini, Sphyrna mokarran, Sphyrna zygaena
Estimated[6]Acuity: 63.75 cycles per degree Measured[7][8]
Field of viewBinocular overlap
13.4°
measured in this species (extension 2026-10, fov-verified.csv)
Measured[9]Binocular overlap: 122.5° Measured[10][11]
Total field of view: 200° Measured (not re-verified)[12]
Blind area behind the head: 160° Derived[12]
Eye placement: frontal Derived[10][11]
Total field of view
338.3°
measured in this species (extension 2026-10, fov-verified.csv)
Measured[9]
Field of one eye
175.9°; horizontal or vertical plane as stated; anaesthetised animals; in water; horizontal plane; mean ± s.e.m. (s.e.m. 1.1)		Measured[9]
Binocular overlap (published value)
13.4°; horizontal or vertical plane as stated; anaesthetised animals; in water; horizontal plane, anterior binocular overlap, physiological (ERG); mean ± s.e.m. (s.e.m. 0.7)		Measured[9]
Total field (published value)
338.3°; horizontal or vertical plane as stated; anaesthetised animals; in water; horizontal plane; mean ± s.e.m. (s.e.m. 2.1)		Measured[9]
Field of one eye, vertical plane
189.1°; horizontal or vertical plane as stated; anaesthetised animals; in water; vertical plane; mean ± s.e.m. (s.e.m. 0.7)		Measured[9]
Binocular overlap, vertical plane
9.1°; horizontal or vertical plane as stated; anaesthetised animals; in water; vertical plane (dorsal and ventral overlap); mean ± s.e.m. (s.e.m. 1.6)		Measured[9]
Total field, vertical plane
360°; horizontal or vertical plane as stated; anaesthetised animals; in water; vertical plane; mean ± s.e.m. (s.e.m. 0.0)		Measured[9]
Sharp zones (foveas)No value in the catalogue.Number of foveas: 1 Measured[13]
Fovea type: fovea Measured[13]
Night visionNo value in the catalogue.Activity pattern: diurnal Measured (not re-verified)[14][15][16][2][17][18][19][20]
Pupil shape: vertical Group default[21][22]
Reflective layer (tapetum): no Measured[23]
Rods vs cones: cone-dominated Derived[14][15][16][2][17][18][19][20]
Night sensitivity (optical, against people): S = 0.93 µm² sr, 1 times people (log10 ratio 0) Derived[24]
Motion (flicker fusion)Flicker fusion frequency
31 Hz
median of 1 bright-light rows (behavioural/whole-eye ERG rows; all rows: [31.0])
Measured[25]Flicker fusion frequency: 60 Hz Measured[26][27]

All sharks and rays side by side: Sharks and rays: every measurement. Method: how we know what animals see.

Sources

  1. Murphy et al. 2022
  2. Longcore 2023
  3. Kirwan
  4. Müller et al. 2009
  5. Thermal Activation and Photoactivation of Visual… 2004
  6. Claes et al. 2014
  7. Kirk et al. 2004
  8. Veilleux et al. 2014
  9. McComb et al. 2009
  10. Heesy 2004
  11. Heffner et al. 1992
  12. Campbell & Green 1965
  13. Kopania et al. 2025
  14. Anderson et al. 2017
  15. Borges et al. 2018
  16. Wilman et al. 2014
  17. Maor et al. 2017
  18. Jones et al. 2009
  19. Schmitz et al. 2011
  20. Moura et al. 2024
  21. Banks et al. 2015
  22. Cervino et al. 2021
  23. Guareschi et al. 2025
  24. Brauburger et al. 2026
  25. Lafitte et al. 2022
  26. Healy et al. 2013
  27. Inger et al. 2014

Every value cites its sources (all sources). Values were extracted from these works and converted (units, medians, derived values); changes are ours, and the listed sources do not endorse this site. Data: catalogue-v1, built 2026-09-29. Accuracy notes: how accurate is this? Method: how we know.