The star-nose is a highly specialized sensory-motor organ shaped by 22 fleshy finger-like appendages, or tendrils, that ring their nostrils and are in constant motion as the mole explores its environment.
This structure is divided into a high resolution central fovea region (the central 11th pair of rays) and less sensitive peripheral areas. In this way, the star works as a “tactile eye” where the peripheral rays (1–10 on each side) study the surroundings with erratic saccade-like movements and direct the 11th ray to objects of interest, just like the primate’s foveating eye.
Regardless of the anatomical position of the star as a distal (protruding or extending) portion of the nose, this is neither an olfactory structure nor an extra hand. The appendages do not contain muscles or bones and are not used to manipulate objects or capture prey. They are controlled by tendons by a complex series of muscles that are attached to the skull in order to perform a role that seems to be purely mechanical.[19] For this purpose, the star also contains a remarkably specialized epidermis covered entirely by 25,000 small raised domes or papillae of approximately 30–50 μm (0.0012–0.0020 in) in diameter.[16] These domes, known as Eimer’s organs, are the only type of receptor organs found in the star of the star-nosed mole, which proves that the star-like structure has clearly a mechanical functioning.
The importance of the star-like nose in the mole’s lifestyle is evidenced in the somatosensory representation of the nose. Electrophysiological experiments using electrodes placed on the cortex during stimulation of the body demonstrated that roughly 52% of the cortex is devoted to the nose. This means that more than half of the brain is dedicated to processing sensory information acquired by this organ, even when the nose itself is only roughly 10% of the mole’s actual size. Thus, it may be concluded that the nose substitutes for the eyes, with the information from it being processed so as to produce a tactile map of the environment under the mole’s nose. As other mammals, the somatosensory cortex of the star-nosed mole is somatotopically organized such that sensory information from adjacent parts of the nose is processed in adjacent regions of the somatosensory cortex. Therefore, the rays are also represented in the brain. The inferior most sensitive pair of rays (11th) had a larger representation on the somatosensory cortex, even when these are the shortest pair of appendages in the nose of the star-nosed mole.
Despite the poorly developed eyes, star-nosed moles have an intricate system to detect prey and understand their environment.[23] During exploration, the mole’s star-like appendage produces brief touches which compress Eimer’s organ against objects or substrate.[16] When foraging, moles search in random patterns of touches lasting 20–30 milliseconds. Catania and colleagues demonstrated that the tactile organ of the star-nosed mole is preferentially innervated by putative light touch fibers. When the outer appendages of the star come into slight contact with a potential food source, the nose is quickly shifted so that one or more touches are made with the fovea (the two lower appendages; 11th pair) to explore objects of interest in more detail – especially potential prey.[7] This foraging behavior is exceptionally fast, such that the mole may touch between 10 and 15 separate areas of the ground every second. It can locate and consume 8 separate prey items in less than 2 seconds and begin searching again for more prey in as little as 120 ms, although the average time is 227 ms.
I feel I now better understand Mole Man.
This speed is unbelievable. Locating and eating 8 prey in 2 seconds ! gotta watch it happen
Meet the star-nosed mole (Condylura cristata), one of the strangest mammals in North America.
Famous for the fleshy star-shaped nose on its face, this underground hunter uses touch faster than almost any animal on Earth.
I’m deducting 5 sanity points from myself for I now recognize that R’lyeh and North America are within each other, and the greatest of the great old ones will be reborn from below my homeland.
ph’nglui mglw’nafh Cthulhu R’lyeh wgah’nagl fhtagn
