Leucism and albinism are two examples of colour mutations that cause colour loss and result in distinct phenotypes. Leucism has a variety of meanings, and some authors refer to it as a form of incomplete albinism. However, leucistic animals have diminished or missing colour but normal eye pigmentation, whereas true albinos lack pigmentation and have red or pinkish eyes. (Turner 2011; Madeira et al. 2020).
Although this phenomenon is rather uncommon, it has been seen in a wide range of animal species (da Costa et al. 2013; Madeira et al. 2020). Leucistic and albino marine turtles are usually mentioned in reports about hatchlings discovered in nests during monitoring efforts. Most reports describe a small number of individuals per nest, which are frequently accompanied by additional morphological anomalies like extra scutes or cranial malformations.
Albino and leucistic marine turtles are rarely observed in the wild, aside from the embryonic and hatchling stages. This may be due to the common congenital defects or the fact that predators can spot albinos and leucistic individuals more easily or incapable of maintaining long-term survival without colouring. However, two leucistic adult green turtles that appeared healthy and successfully laid eggs in 2018 at Tortuguero National Park in Costa Rica show that some of these individuals may survive into adulthood (Restrepo & Valverde 2019; Madeira et al. 2020). Some researchers have noted that albinos’ vision and/or sea-finding abilities may be hampered by the retina’s lack of pigmentation (Perrault & Coppenrath 2019; Madeira et al. 2020).
References:
- da Costa, J. de N., A.B. Barros, R.M. de Miranda, E.J. Almeida & D.J. Rodrigue. 2013. Record of leucism in Pseudoboa nigra Serpents: Dipsadidae) in southern Amazon, Brazil. Herpetology Notes 61: 81-82.
- Madeira F., Patricio A., Indjai B., Barbosa C., Regalla A., Catry P., Rebelo R. (2020). High Number of Healthy Albino Green Turtles from Africa’s Largest Population. Marine Turtle Newsletter. 19-22.
- Perraul, J.R. & C.M. Coppenrath. 2019. Albinism In Florida green turtle (Chelonia mydas) hatchlings: ratio-based evidence of basic Mendelian recessiveness. Marine Turtle Newsletter 156: 38-40.
- Restrepo, J. & R.A. Valverde. 2019. Leucistic adult female green sea turtles (Chelonia mydas) successfully nesting at Tortuguero, Costa Rica. Marine Turtle Newsletter 159: 23-25.
- Turner, G.S. 2011. Hypomelanism in Irwins Turtle, Elseya irwini, from the Johnstone River, North Queensland, Australia. Chelonian Conservation & Biology 102: 275-281
