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Claws protract to grip prey: African lion


Lion view / S. Taheri / LicenseCC-by-sa - Attribution Share Alike

Claws of the African lion protract from sheaths of skin to grab prey using muscles and tendons.

The African lion has a remarkable adaptation for hunting. Unlike other carnivores that commonly have permanently extended claws, lions (and most other cats) sport protractile claws. With this protraction mechanism, the claws are either passively retracted within the paw or actively extended out of the paw. In the paw's relaxed state, elastic ligaments and tendons hold the claws within sheaths of skin. In this state, the claws are protected from the wear and tear that comes from walking on rough ground. Using this covering is like keeping a sword in its scabbard to protect it from becoming dull. When the lion is ready for action, it uses muscles to actively straighten its toes and extend its blade-like claws from their sheaths. This specialized arrangement enables the lion to control when to use its sharp claws for hunting, as well as climbing and mating.
Schematic of the African lion's paw Illustration created by Sam GochmanSome rights reserved.

This summary was contributed by 
Sam Gochman.

"Cats can grip with their front paws with more than just flexibility: they have protractile claws, like blades that simultaneously fire from each paw! (To call them 'retractile' is to misunderstand the animal's behavior.) In a normal relaxed state the claw is sheathed, but when the paw is extended, ready to strike (in a similar move to our opening our hands wide) the curved claws project." (Tabor 2003: 14)

"The bones at the end of each toe are usually pulled up and back by strong elastic tendons, withdrawing a lion's claws into sheaths of skin. This arrangement keeps the claws from becoming blunted by contact with the ground as the lion walks or runs. When it needs them for seizing prey, the lion contracts muscles that straighten the toe bones and make the sharp claws protrude from their sheaths." (Marshall Cavendish Corporation 2010: 171)

"Cats are renowned for their protractile claws. Both the terminal and penultimate phalanges of felids... are modified to allow passive retraction and active protraction... The claws remain hidden within fleshy sheaths, being held in place by ligaments and tendons, so that they are not blunted by contact with the substrate." (Kitchener et al. 2010: 93)
About the inspiring organism
Med_screenshot20150701at4.42.19pm Lion
Panthera leo (Linnaeus, 1758)
Common name: African lion

Habitat(s): Desert, Forest, Grassland, Savanna, Shrubland
Learn more at EOL.org
Some organism data provided by: ITIS: The Integrated Taxonomic Information System
Organism/taxonomy data provided by:
Species 2000 & ITIS Catalogue of Life: 2008 Annual Checklist

Threat Categories LONG_VU IUCN Red List Status: Vulnerable

Bioinspired products and application ideas

Application Ideas: Tires or vehicles that function well on various terrains, safety devices for equipment that functions at various speeds, protractable awnings, protractable needles or internal medical equipment, protractable crampon/gripping footwear

Industrial Sector(s) interested in this strategy: Transportation, safety, manufacturing, building, medical

Tabor R. 2003. Understanding Cat Behavior. Newton Abbot (England): David & Charles. 144 p.
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Marshall Cavendish Corporation. 2010. Mammal Anatomy: An Illustrated Guide. New York (NY): Cavendish Square Publishing. 171 p.
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Kitchener A. C., Van Valkenburgh B., and Yamaguchi N. 2010. Felid form and function. In: MacDonald, D. and Loveridge, A., editors. Biology and Conservation of Wild Felids. Oxford: Oxford University Press. p 83-106
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over 2 years ago
Dear Ivy White,

Thank you for this comment. We are reviewing this strategy to ensure accuracy. Thank you for calling this to our attention!

over 2 years ago
Cats do NOT have "retractable claws". This would imply that their claws are extended at all times and that they can withdraw them at will. This is not the case. Cats have Protractile claws. This means that when the muscles are relaxed, the claws are pulled back into the sheath and only come out when the cat wants them to come out and exercises the proper muscles to make this happen. To retract is to actively pull back when in fact, it is the passive relaxation of the muscles which causes the claws to be sheathed. There are some large cats whose claws are extended like a dogs all of the time, One of these is the Cheetah, primarily as the cheetah lacks a sheath.
over 3 years ago
Each paw is equipped with soft pads to make it's movements quiet. Like most carnivores, lions are digitigrade walkers. This means they essentially walk on their toes. But, the majority of the animal's weight is borne by the main paw pads, which would correspond on a human to the palm of the hand at the base of the fingers. Extra bones in the toe joints give the toes a wide range of motion.The claws are retractible and very sharp. The retractable feature helps keep the claws sharp, and prevents injury during play, etc. The dewclaw on the front limbs is often used as a toothpick. The claws grow as a series of layers. As a layer wears, it is shed, and a new sharp-pointed claw is exposed. The claw on a large lion can be 1 1/2 inches (38 mm) or more from base to tip along the curve.

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