Posted by Laura Brown on May 25, 2006

Q: Hello,

I was wondering if you could tell me which animals have tapetum lucidum? I know that nocturnal hunters have them, and also someone said underwater mammals have them but I'm not so sure. Thanks and I look forward to hearing from you!

A: I found a brief discussion online of the different kinds of tapetum lucidums with a list of animals that I'll share for you. It's a bit formal so I'll add a few comments to make it more user-friendly.

"Some species (primates, squirrels, birds, red kangaroo and pig) do not have this structure and they usually are diurnal animals. In vertebrates, the tapetum

lucidum exhibits diverse structure, organization and composition. Therefore, the retinal tapetum (teleosts (bony fishes), crocodilians, marsupials (pouched mammals), fruit bat), the choroidal guanine tapetum (elasmobranchs (sharks), the choroidal tapetum cellulosum (carnivores, rodents, cetacea (whales and porpoises), and the choroidal tapetum fibrosum (cow, sheep, goat, horse) are described."

So it does look like at least some of the underwater mammals do indeed have a tapetum lucidum. I'm quite sure there are other mammals not included in this piece but you can probably figure that those living in a rather dark environment, whether water or nocturnal, are most likely to have this adaptation. Hope this helps.

John Wiessinger ( May 26, 2006)