Alligator Osteoderm Armor

An American Alligator`s body hide is covered in hard, boney scutes, called osteoderms, that make the skin very tough and hard. American Alligator photographed along the Suwannee River Middle Fork canoe trail in the Okefenokee National Wildlife Refuge, Georgia USA. October 23, 2020 ©www.williamwisephoto.com

All along its back – from neck to tail – the American Alligator is armored with bony scales called osteoderms. Also called scutes – derived from a Latin word meaning “shield” – these osteoderms are arranged in rows below the alligator’s thick, leathery skin. Each osteoderms is square-ish or disc-like and has a high ridge through the middle of the upper surface called a keel. The rows of keels are what give the alligator that “spiked” appearance. Not only do the osteoderms act as protective armor, but they also help with thermoregulation. The osteoderms are porous, and not solid bone. They are networked with blood vessels and can act as heat exchangers to warm up or cool down this “cold-blooded”, or ectothermic, reptile.


  • Ouchley, K.. American Alligator: Ancient Predator in the Modern World. University Press of Florida, 2013.
  • ​Chen IH, Yang W, Meyers MA. Alligator osteoderms: mechanical behavior and hierarchical structure. Mater Sci Eng C Mater Biol Appl. 2014;35:441-448. doi:10.1016/j.msec.2013.11.024
  • iNaturalist observation: https://www.inaturalist.org/observations/64432964

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