Mole's Star

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Salisbury, David F. (2 February 2005). "Marsh-dwelling mole gives new meaning to the term 'fast food' ". EurekAlert. Archived from the original on 16 August 2016 . Retrieved 19 August 2016. Examination of the threshold of velocity at which the receptors responded identified that the minimum velocity of cell response was 46mm/s, corresponding to the approximate speed of the nose during foraging behavior. [22] Transduction of the mechanical signal [ edit ] In 1996, Vanderbilt PhD candidate Paul Marasco determined that the threshold by which the star-like structure senses the mechanical stimuli depends on which type of the Eimer’s organ was excited. He characterized three main classes of Eimer’s receptors, including one of slow adaptation ( Tonic receptor) and two of rapid adaptation ( Phasic receptor). The tonic receptor has a response similar to that of a Merkel cell- neurite complex. It has free terminals and is therefore able to detect pressure and texture with a high sensitivity and at a Random Sustained Discharge. The rapid adapting responses include a Pacinian-like response based on an (on-off) response caused by pressure and mechanical vibrations with maximum sensitivity to stimuli at a frequency of 250 Hz. The differences between both rapid responses rely on the fact that one of them only has a response during the compression phase. [16] [22] Frequency sensitivity [ edit ]

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Catania, K.C. (1999). "A nose that looks like a hand and acts like an eye: the unusual mechanosensory system of the star-nosed mole". Journal of Comparative Physiology A. 185 (4): 367–372. doi: 10.1007/s003590050396. PMID 10555270. S2CID 15216919. Studies of the embryos revealed that appendage 11 was the largest appendage during early development, despite its relatively small size in adults. It also became clear that Eimer's organs on the star, and the neural structures within each Eimer's organ, matured first on the 11th appendage. It is as if this appendage gets a head start compared with all the other ones, which later overtake it in size and number of Eimer's organs. As it turns out, the retinal fovea in the visual system also matures early. Credit:Kenneth C. Catania ( micrographs) Controlling the Eastern Mole”– University of Arkansas System. Accessed July 02, 2019. https://www.uaex.edu/publications/pdf/FSA-9095.pdf.Mole, as a term, refers to any species in the family Talpidae (which simply means “mole” in Latin). The earliest of the species probably evolved in the Eocene Epoch some 34 to 55 million years ago somewhere in Europe and then spread out from there over the ensuing millions of years. The mole is an animal with a striking, distinctive appearance, well-adapted for its burrowing lifestyle. Its massive hands, short limbs, and sharp claws enable it to burrow through the ground with relative ease. These hands also sometimes make excellent paddles for swimming. What’s really remarkable about the physical characteristics is that these huge forepaws contain two thumbs each. Whereas the other fingers have multiple joints, the thumbs are only composed of a single bone.

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Sawyer, Eva; Leitch, Duncan; Catania, Kenneth (1 October 2014). "Organization of the Spinal Trigeminal Nucleus in Star-Nosed Moles". Journal of Comparative Neurology. 522 (14): 3335–3350. doi: 10.1002/cne.23605. PMC 4107073. PMID 24715542. Catania, Kenneth C. (2012). "Tactile sensing in specialized predators – from behavior to the brain". Current Opinion in Neurobiology. Elsevier. 22 (2): 251–258. doi: 10.1016/j.conb.2011.11.014. PMID 22209039. S2CID 5343590. The various mole species are grouped into different subfamilies as follows. Asian Shrew Moles – Uropsilinae Each Eimer’s organ is supplied by a number of primary afferents, thus the star is densely innervated. [19] It is associated with a Merkel cell- neurite complex at the base of the cell column, a lamellated corpuscle in the dermis just below the column and a series of free nerve endings that originate from myelinated fibers in the dermis, run through the central column and end in a ring of terminal swellings just below the outer keratinized skin surface. [16] All 25,000 Eimer’s organs distributed along the surface of the star have this basic structure in all 22 appendages. Nevertheless, the fovea region (11th pair of rays), which is shorter in area, has a lower density of these organs – 900 Eimer's organs on its surface while some of the lateral rays have over 1500. This may sound contradictory with the fact that this region has higher resolution and an important role in foraging behavior. However, instead of having more sensory organs this fovea region uses a different approach in which a skin surface may be more sensitive to mechanoreceptic input; it has more innervation density. Rays 1 through 9 each has about 4 fibers per Eimer's organ, while rays 10 and 11 have significantly higher innervation densities of 5.6 and 7.1 fibers per organ, respectively, [19] revealing how the sensory periphery is differentially specialized across the star.

The small and defenseless mole animals are often preyed upon by foxes, coyotes, weasels, snakes, hawks, and owls. Because the moles are so vulnerable above ground, the burrow provides a natural defense against most predators. However, this may not save the mole from predators with a very good ability for digging. Pups leave the nest 33 days after birth to find territories of their own. They disperse from their mother's range around 5–6 weeks and they become sexually mature during the spring following their birth. [16] Social structure [ edit ] The gestation period of the Eastern (North America) mole (Scalopus aquaticus) is approximately 42 days. Three to five young are born, mainly in March and early April. [13]