Thick-skinned but sensitive

Crocodiles and alligators may sense their prey using tiny bumps on their mouths that are highly sensitive to touch.

Kenneth Catania and Duncan Leitch at Vanderbilt University in Nashville, Tennessee, investigated the raised bumps أ¢â‚¬â€‌ called integumentary sensory organs أ¢â‚¬â€‌ in 18 American alligators (Alligator mississippiensis; hatchling pictured) and 4 Nile crocodiles (Crocodylus niloticus). Confocal microscopy revealed that the bumps (pictured yellow), which are packed most tightly around the teeth and mouth, share similar structures with tactile skin receptors in mammals. The bumps seemed to be insensitive to electrical current or water salinity, but showed nerve responses when stimulated with a range of levels of force أ¢â‚¬â€‌ responding to low levels with a sensitivity exceeding that in primate fingertips.

The authors suggest that the animals use the sensitive bumps to locate prey, and to identify food and other items inside their mouths.