Grooming claw

A grooming claw (or toilet claw) is the specialized claw or nail on the foot of certain primates, used for personal grooming. All prosimians have a grooming claw, but the digit that is specialized in this manner varies.[1] Tarsiers have a grooming claw on second and third toes (but they are not prosimians). In the suborder Strepsirrhini, which includes lemurs, galagos and lorises, the grooming claw is on the second toe.[2] Less commonly known, a grooming claw is also found on the second pedal digit of night monkeys (Aotus), titis (Callicebus), and possibly other New World monkeys.[3]

Close-up of a ruffed lemur's foot, showing the toilet-claw on the second toe and nails on all other toes

The first toe is the large one, the equivalent of a human big toe. However, in all these prosimians the foot is more or less hand-like. The first toe is opposable, like a human thumb, and the second and third toes correspond approximately to the index and middle fingers.

Like a claw or a nail, the grooming claw is also made of keratin. It resembles a claw in both its lateral compression and longitudinal curvature. However, the tip is not as pointed, and it always stands at a steeper angle, a characteristic that also distinguishes it from a nail.[1]

Function

The grooming claw is used in personal grooming to rake through the fur or scratch, particularly around the head and neck.[3]

References
  1. Soligo, C.; Müller, A. E. (1999). "Nails and claws in primate evolution". Journal of Human Evolution. 36 (1): 97–114. doi:10.1006/jhev.1998.0263. PMID 9924135.
  2. Schwitzer, C; Mittermeier, R. A.; Louis Jr., E. E.; Richardson, M. C. (2013). "Family Daubentoniidae: Aye-aye". In Mittermeier, Russell A.; Rylands, Anthony B.; Wilson, Don E. (eds.). Handbook of the Mammals of the World. Volume 3. Primates. Barcelona: Lynx Edicions. pp. 176–181. ISBN 978-84-96553-89-7.
  3. Maiolino, S.; Boyer, D. M.; Rosenberger, A. (2011). "Morphological Correlates of the Grooming Claw in Distal Phalanges of Platyrrhines and Other Primates: A Preliminary Study". The Anatomical Record. 294 (12): 1975–90. doi:10.1002/ar.21498. PMID 22042603.
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