Star-nosed mole

Article By:

Campbell, Kevin L. Department of Biological Sciences, University of Manitoba, Winnipeg, Canada.

Price, Nadine T. Department of Biological Sciences, University of Manitoba, Winnipeg, Canada.

Last reviewed:2011

DOI:https://doi.org/10.1036/1097-8542.YB110091

The star-nosed mole, Condylura cristata (Fig. 1), is one of the true oddities of the animal kingdom. This distinction arises not only from the 22 conspicuous nasal appendages (the “star”) that fan concentrically outward from its nostrils, but also from the ability of this functionally blind insectivore to successfully navigate and exploit the underwater environment for feeding on aquatic annelids and other small invertebrates. The aquatic medium poses particular challenges for terrestrial animals as they are limited to relatively brief underwater excursions because of the necessity to obtain oxygen from the atmosphere. This problem is amplified for small amphibious predators, including the star-nosed mole [40–60 g (1.4–2.1 oz)], as they carry far less oxygen stores underwater than larger aquatic animals and consume the oxygen at a much faster rate. This occurs because the oxygen requirement of each gram of cells increases disproportionately as animal size decreases, following a process called allometric scaling. Consequently, 1 g (0.035 oz) of star-nosed mole tissue consumes about 10 times more oxygen per second than does the same mass of tissue from a 500-kg (1100-lb) seal. As a result, most voluntary dives by star-nosed moles last less than 10 s in duration, with few underwater excursions exceeding 20 s. This strict limitation has led to the evolution of several remarkable specializations that have allowed this semiaquatic mole to increase the speed and efficiency with which it can locate and identify prey while submerged.

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