Nature’s Oddities Part 4: the Star-Nosed Mole

Even uglier than the hagfish, the blind star-nosed mole, Condylura cristata spends most of its time tunneling in damp soil looking for food. The star-nosed mole features oversized and extremely powerful forelimbs highly adapted for digging. I has very smooth and dense fur, which makes it a great swimmer and capable of swimming in freezing cold waters (something no other mole accomplishes). It has litters of 4-5, and is a decent parent by mammalian standards.



By far its most remarkable feature is the “star.” This highly modified nose has 22 fleshy, highly vascularized, appendages literally packed with Eimer's organ’s, which are tiny specialized sensory-motor receptors unique to moles. Over 25,000 of these receptors are distributed over the surface of the appendages. This is a remarkable concentration. To make a comparison, I will use the human hand. The density of motor-receptors on the human hand is so low that to match the star’s density, every receptor site on both hands would have to be relocated on to a single patch of skin the size of a fingernail. Yes, the mole’s ability to feel with its star is that much more acute than our ability to feel with our hands.



Even better, the mole utilizes a special neuronal pathway for communicating sensory data from its receptors to its brain that no other animal utilizes for sensory-receptors. It is a very direct and short pathway, which greatly conserves the amount of nervous tissue necessary to get the job done, and it is quite similar to the pathway used by the human eye. This allows the mole to make decisions about what it feels so fast that they approach the limit of neuron’s speed.

As the mole travels through the soil it wiggles its 22 appendages constantly, gathering more sensory data than we can imagine from its star. This constant vigilance, combined with the mole’s rapid decision making ability, allows the mole to be the fastest eater on earth (120 milliseconds to identify and consume individual food items). Not even certain species of fish, with entirely reflexive (no cognitive processing) bite movements, can compare. When the mole encounters a morsel it decides is edible, it rapidly ingests the often-tiny bit of food with its precise, tweezer-like teeth. This remarkably rapid decision-making and ability to grasp tiny bits of food allow the star-nosed mole to utilize food sources most animals its size cannot. See, it’s a principal of biological thermodynamics that larger prey is a more efficient source of food. It takes far less energy, per pound of meat obtained, to subdue a cow that it takes to subdue several hundred rabbits. Each rabbit needs to be chased down and killed. The same principle exists on a smaller scale. Often shrews, rats, and mice overlook critters like nematodes and small worms and invertebrates because tracking, grasping, and ingesting them will consume more energy than the prey’s body will yield through digestion. The star nosed-mole, though, is a master of small prey. It is so efficient and detecting them (with is super sensor nose) and subduing them (with its tweezer teeth) that no other small mammal compares. This has led to enormous success for the star-nose, and its range extends from the swamps of South Carolina all the way to northern Canada.

The star-nose spends almost its entire life several meters below the soil (but always around one meter above the waterline), so it has few natural predators. Sometimes owls, snakes, hawks, and weasel-like mammals prey upon the star nose, but it’s mostly loss of habitat that harms them. Unlike the lamprey and hagfish, which mock (or downright exploit) man’s meddling in the world, the star-nose stands to lose from it.