The star-nosed mole, Condylura cristata, is a peculiar mammal. This small, mole-like creature measures 6 to 8 inches in length and weighs around 0.12 pounds. It is easily recognized by a unique appendage on its snout. Its body is covered in dense, dark brownish-black fur, adapted for its moist environment. While its overall appearance is similar to other moles, this distinctive feature sets it apart.
The Function of the Star
The star on the mole’s snout functions as a highly sensitive touch organ, not for smelling. This structure is composed of 22 fleshy, pink rays that radiate symmetrically around its nostrils. Each ray is densely covered by thousands of microscopic sensory receptors, known as Eimer’s organs, with over 25,000 such organs on the star.
Eimer’s organs contain specialized nerve endings, including Merkel cell-neurite complexes and lamellated corpuscles, which detect minute shapes and textures. These receptors are sensitive, transmitting tactile information to the mole’s brain rapidly. The mole’s brain dedicates a disproportionately large area of its somatosensory cortex to processing signals from the star, creating a detailed “touch map” of its surroundings, much like other mammals use a visual map. The two shortest rays at the bottom center of the star possess the highest density of these organs, functioning similarly to a visual fovea for high-resolution tactile exploration.
Habitat and Diet
Star-nosed moles are native to eastern North America, inhabiting a range extending from eastern Canada south to Georgia and west to Manitoba and North Dakota. These moles prefer wet, low-lying areas, including marshes, bogs, wet meadows, and the banks of streams, lakes, and ponds. Their preference for poorly drained, saturated soils has likely influenced the evolution of their highly sensitive snout.
They are semi-aquatic, demonstrating proficiency in swimming and often constructing tunnel systems that include underwater entrances. While they primarily dig shallow foraging tunnels, they can also venture into water to hunt. Their diet consists of small invertebrates, including aquatic insects like caddisflies, midges, and dragonflies, as well as earthworms, leeches, mollusks, and small crustaceans. They also consume small amphibians and fish, adapting their prey selection to the availability in their moist habitats.
Foraging and Feeding Habits
The star-nosed mole uses its star appendage to navigate its dark subterranean and aquatic environments to locate food. As it explores, the mole continuously brushes its surroundings with the outer rays of its star, performing rapid touches against objects or the substrate. This constant probing allows it to quickly scan for potential prey.
Upon detecting a possible food item, the mole swiftly focuses its two most sensitive central rays onto the object for precise identification. This process is extraordinarily fast; the star-nosed mole is recognized as the fastest-eating mammal, capable of identifying and consuming a small food item in as little as 120 milliseconds, with an average handling time of 230 milliseconds. Its brain can decide if prey is edible in approximately 8 milliseconds. This speed highlights the specialized function of its star in efficiently acquiring food within its damp habitat.