Hellbender Essay Example For Students

Hellbender Essay The Eastern Hellbender (Cryptobranchus alleganiensis alleganiensis)Cryptobranchus alleganiensis alleganiensis is the largest North Americansalamander, ranging in length from 30.5 to 74 cm (Niering 1985). EasternHellbenders are members of the order of tailed amphibians, Caudata and thefamily, Cryptobranchidae. Along with C. a. bishopi, the Ozark Hellbender, it isone of the two subspecies of hellbenders, also known as the Allegheny alligatoror devil-dog. C. a. alleganiensis is perennially aquatic, preferring clearfast-moving rivers or large streams with rocky bottoms. Most are found in water12 to 46 cm deep and tend to avoid areas with thick layers of silt (Hillis andBellis 1971). It ranges from the Susquehanna River and its tributaries in NewYork and Pennsylvania to the Ohio River and its tributaries including theAllegheny, which gives it its species name, westward to the Mississippi Riverand southward to Missouri, Arkansas, and Georgia. It has also been recorded inIowa (Bishop 1943). C. a. alleganiensis has a dorsoventrally flattened body anda laterally flattened tail. The tail is the main means of locomotion, but thehellbender can also crawl when seeking refuge (Hillis and Bellis 1971). C. a. alleganiensis is dark gray or olive-brown with a mottled or spotted pattern onits dorsal surface. The ventral surface is a lighter shade with few markings (Niering1985). The male and female are similar in appearance, but the male is broaderand heavier than a female of the same length. Eyelids are absent. It has fivetoes on its hind feet and four on the fore feet, most of which develop duringthe larval stage (Bishop 1943). C. a. alleganiensis is nocturnal, spending itsdays hiding under rocks with only the tip of its broad head exposed. It exhibitsdiurnal behavior only during its mating season which occurs in late summer orearly fall depending on geographic location. (Hillis and Bellis 1971). C. a. alleganiensis practices external fertilization. The male will dig asaucer-shaped nest-like cavity beneath a large, flat rock or sunken log. Thefemale lays 200-500 yellowish eggs in long strings. The male assumes a matingposition above or behind the female and sprays the eggs. The male will thenremain in the area to guard the nest (Niering 1985). Evidence has shown that themale will eat some of these eggs and therefore may remain more to guard his foodsupply than from a sense of parental responsibility (Hillis and Bellis 1971). The larvae will latch two to three months later. The larva are approximately 30mm long and born with gills which they will lose when they are 100-130 mm longat about 18 months, leaving only a single pair of gill slits (Bishop 1943). Thehellbenders principle food source appears to be crayfish, this is most likelyfor convenience since crayfish hide in similar locations as the hellbender. Therest of its diet is composed mainly of other aquatic invertebrates such asmolluscs, worms, and insects. They have also been observed to eat small fish andanimal refuse (Hillis and Bellis 1971). BibliographyBishop, S.C. 1943. Handbook of Salamanders. pp. 59-63. Comstock PublishingAssociates, Ithaca, NY. Hillis, R.E. and E.D. Bellis. 1971. Some aspects of theecology of the hellbender, Cryptobranchus alleganiensis alleganiensis, in aPennsylvania stream. Journal of Herpetology, 5:121-126. Niering, W.A. 1985. National Audubon Society Nature Guides: Wetlands. pp. 384-385. Alfred A. Knopf,Inc., New York, NY.