Taxonomy and Physical Description
The genus Cryptobranchus has historically only been considered to contain one species, Cryptobranchus alleganiensis, with two subspecies, Cryptobranchus alleganiensis alleganiensis and Cryptobranchus alleganiensis bishopi. Recent decline in population size of the Ozark subspecies Cryptobranchus alleganiensis bishopi has led to further research into populations of this subspecies, including genetic analysis to determine the best route for conservation status. Crowhurst et al., for instance, found that the “Ozark subspecies” denomination is insufficient for describing genetic (and therefore evolutionary) divergence within the Cryptobranchus genus in the Ozark region. The researchers found three equally divergent genetic units within the genus: Cryptobranchus alleganiensis alleganiensis, and two distinct eastern and western populations of Cryptobranchus alleganiensis bishopi. These three groups were shown to be isolated and are considered to most likely be “diverging on different evolutionary paths".
Both males and females grow to an adult length of 24 centimetres (9.4 in) to 40 centimetres (16 in) from snout to vent, with a total length of 30 centimetres (12 in) to 74 centimetres (29 in) making it the third largest aquatic salamander species in the world (next to the Chinese giant salamander and the Japanese giant salamander) and the largest in North America. An adult weighs 1.5 kilograms (3.3 lb) to 2.5 kilograms (5.5 lb). Hellbenders reach sexual maturity at about five years of age, and may live thirty years in captivity.
C. alleganiensis have flat bodies and heads, with beady dorsal eyes and slimy skin. Like most salamanders, they have short legs with four toes on the front legs and five on their back appendages, and their tails are keeled to propel them through water. The hellbender has working lungs, but gill slits are often retained although only immature specimens have true gills; the hellbender absorbs oxygen from the water through capillaries of its side-frills. They are blotchy brown or red-brown in color, with a paler underbelly.
Read more about this topic: Hellbender
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