Southern grasshopper mouse
|Southern grasshopper mouse|
The southern grasshopper mouse or scorpion mouse (Onychomys torridus) is a species of rodent in the family Cricetidae. It is found in Mexico and in Arizona, California, Nevada, New Mexico, and Utah in the United States. Notable for its resistance to venom, it routinely kills and eats Arizona bark scorpions, a species with a highly poisonous sting.
The southern grasshopper mouse is a robust, medium-sized species with a short tail, growing to a total length of 120 to 163 mm (4.7 to 6.4 in). The head, back and sides are pinkish- or grayish-brown while the underparts are white, the two colors being distinctly separated. The tail is club-shaped, short and broad, the anterior part being the same color as the body and the tip being white.
The southern grasshopper mouse feeds almost entirely on arthropods, such as beetles, grasshoppers and scorpions. Besides these, it preys on the little pocket mouse (Perognathus longimembris) and the western harvest mouse (Reithrodontomys megalotis).
In the arid regions inhabited by the southern grasshopper mouse, the Arizona bark scorpion is plentiful and avoided by most predators because of the very painful sting it can inflict. The grasshopper mouse can feed on this scorpion with impunity even when the scorpion stings it repeatedly in the face. Researchers have found that a neural mechanism is involved that blocks the sending of pain messages to the brain. This mouse can normally feel pain from other sources, but can be temporarily insensitive to these stimuli after a dose of venom from a bark scorpion.
Females are able to produce several litters in a year but their reproductive life is short, few breeding successfully in their second year. The average litter size is 2.6 (range 1 to 5), produced after an average gestation period of 29 days. The young are born naked, with pink translucent skin. One day later the pigment is developing on the dorsal surface and by day ten, hairs 3 millimetres (0.12 in) long are present on the back. The eyes open on day 15 and solid food is being consumed by day 19. The females give birth to their first litter when four or five months old.
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- Musser, G. G.; Carleton, M. D. (2005). "Superfamily Muroidea". In Wilson, D. E.; Reeder, D. M. Mammal Species of the World (3rd ed.). Johns Hopkins University Press. p. 1061. ISBN 978-0-8018-8221-0. OCLC 62265494.
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- Wade, Lizzie (24 October 2013). "Mouse impervious to scorpion's sting". Science. Retrieved 16 September 2014.
- Reardon, S. (1 November 2013). "Zoologger: Mouse eats scorpions and howls at the moon". NewScientist.