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Grasshopper mice Temporal range: Early Pliocene – Present
A grasshopper mouse eating a beetle
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Chordata
Class:	Mammalia
Order:	Rodentia
Family:	Cricetidae
Subfamily:	Neotominae
Tribe:	Reithrodontomyini
Genus:	Onychomys Baird, 1857
Type species
Hypudaeus leucogaster
Species
Onychomys arenicola Onychomys leucogaster Onychomys torridus

Grasshopper mice are rodents of the genus Onychomys, occurring in North America. They feed on insects and other arthropods.

Biology

The three species in this genus of New World mice are only distantly related to the common house mouse, Mus musculus. They are endemic to the United States and Mexico. The southern grasshopper mouse has around a 3.5 to 5.0 inches (8.9–12.7 cm) long body and a tail that is generally 1.0 to 2.5 inches (2.5–6.4 cm) long. Its behavior is distinct from other mice.

It is a carnivorous rodent, dining on insects (such as grasshoppers), worms, spiders, centipedes, mantis, scorpions, snakes, and even other mice. It also stalks its prey in the manner of a cat, sneaking up quietly, and defends its territory by "howling" like a small wolf. The grasshopper mouse is known to be immune to various venoms released by its prey (scorpions, snakes, etc.). Grasshopper mice are nocturnal and avoid exposure to bright light.

Ecology

Diet

Grasshopper mice prey on highly venomous arthropods. One example is centipedes that normally kill less resistant mice by injecting deadly toxins through their venomous forcipules. Grasshopper mice move swiftly, while centipedes can only inject their toxin if their prey is held by the centipede's needle-sharp claws. The mouse is agile enough to stay out of the reach of the centipede's claws. The mouse attacks by repeatedly biting through the centipede's hard exoskeleton. Each attack on the centipede damages its central nervous system, until the centipede is paralyzed and the grasshopper mouse can eat it safely.

Another example of a venomous arthropod is the bark scorpion (Centruroides sculpturatus). The grasshopper mouse survives in the deserts of southwest United States by feeding on the bark scorpion, which are plentiful, due to other resources being less common.

Their aggressive nature extends beyond their hunting habits: when held in captivity with other mice, they will often kill and eat those other mice. However, they have a disadvantage when it involves capturing in open areas because of their short legs and wide bodies (which reduces their speed). Due to their ability to maneuver well, they are able to move quickly in narrow areas allowing them to capture their prey more efficiently.

Physiology

Pain tolerance

The bark scorpion and the grasshopper mouse have been coevolving with each other so closely that it has affected their physiology. The scorpion uses its stinger to inject toxins into the nervous and muscle tissues which causes disruption in the animal's sensory system. However, as the scorpion's stinger evolves to become more toxic, the mice evolve in order to cope with the toxins. Grasshopper mice have evolved sensory neurons which reject the toxins and prevent pain signals. Researchers now know that the grasshopper mouse barely notices the intensifying sting due to a mutation in the cellular pathway that controls their pain response. Compared to the normal house mouse, the grasshopper mouse has one more amino acid in the protein making up the sodium channel Na+ nav1.8. This change prevents the mouse from processing Na+ currents when injected with the scorpion's venom, which blocks action potential propagation and induces analgesia. The Grasshopper Mouse's mutation may potentially yield better analgesics for humans as well, through further research.

Communication

Onychomys have six different vocalization types (two neonatal and four adult). They have a wide range of calls that can distinguish them between species, sex, and individuals. For example, the larger mice tend to have deeper voices. When they feel attacked, they will let out a rapid screech/bark.

Species

• Mearns's grasshopper mouse or Chihuahuan grasshopper mouse Onychomys arenicola
• Northern grasshopper mouse, Onychomys leucogaster
• Southern grasshopper mouse, Onychomys torridus

References

1. Wilson, D. E.; Reeder, D. M., eds. (2005). Mammal Species of the World: A Taxonomic and Geographic Reference (3rd ed.). Johns Hopkins University Press. ISBN 978-0-8018-8221-0. OCLC 62265494.
2. "Mearns' Grasshopper Mouse (Onychomys Arenicola)." Mearns' Grasshopper Mouse (Onychomys Arenicola). The Mammals of Texas- Online Edition, n.d. Web. 10 April 2013.
3. Onychomys: Tiny Terror of the Western Deserts
4. ^ Bailey, Vernon; Sperry, Charles (November 1929). "Life History And Habits Of Grasshopper Mice, Genus Onychomys". google scholar. United States Department of Agriculture.
5. ^ Thompson, Benjamin (June 2018). "The Grasshopper Mouse and Bark Scorpion: Evolutionary Biology Meets Pain Modulation and Selective Receptor Inactivation". The Journal of Undergraduate Neuroscience Education. 16 (2): R51–R53. PMC 6057761. PMID 30057511.
6. Rowe, Ashlee H.; Rowe, Matthew P. (November 2, 2015). "Predatory grasshopper mice" (PDF). Current Biology. 25 (21): R1023–R1026. doi:10.1016/j.cub.2015.07.054. ISSN 0960-9822. PMID 26528738 – via CORE.
7. Rowe, Ashlee (October 2013). "Voltage-Gated Sodium Channel in Grasshopper Mice Defends Against Bark Scorpion Toxin". Science. 342 (6157): 441–446. Bibcode:2013Sci...342..441R. doi:10.1126/science.1236451. PMC 4172297. PMID 24159039.
8. Hafner, Mark; Hafner, David (20 February 1979). "Vocalizations of Grasshopper Mice (Genus Onychomys)". Journal of Mammalogy. 60 (1): 85–94. doi:10.2307/1379761. JSTOR 1379761.

• The Mammals of Texas: Mearns' grasshopper mouse
• The Mammals of Texas: Northern grasshopper mouse Archived 2018-10-05 at the Wayback Machine
• University of Michigan Animal Diversity Web: Genus Onychomys

v t e Myomorpha
Kingdom: Animalia Phylum: Chordata Class: Mammalia Order: Rodentia
Myomorpha †Anomalomyidae Anomalomys Anomalospalax Prospalax Dipodoidea †Aksyiromys †Banyuesminthus †Elmymys †Primisminthus †Simiacritomys Dipodidae Allactaginae Allactaga Allactodipus Pygeretmus Scarturus Cardiocraniinae Cardiocranius Salpingotulus Salpingotus Dipodinae Dipodini Dipus Eremodipus Jaculus Stylodipus Paradipodini Paradipus Euchoreutinae Euchoreutes †Simimyidae Nonomys Simimys Sminthidae †Allosminthus †Gobiosminthus †Heosminthus †Heterosminthus †Lophocricetus †Macrognathomys †Megasminthus †Miosicista †Paraminthus †Schaubemys †Shamosminthus Sicista †Sinosminthus †Tyrannomys Zapodidae Eozapus †Javazapus Napaeozapus †Pliozapus †Sinozapus †Sminthozapus Zapus Muroidea †Armintomyidae Armintomys Platacanthomyidae †Neocometes Platacanthomys Typhlomys Spalacidae Myospalacinae Eospalax Myospalax †Pliosiphneus Rhizomyinae †Brachyrhizomys Cannomys Rhizomys Tachyoryctes Spalacinae Nannospalax Spalax Eumuroida See below↓
Eumuroida Calomyscidae Calomyscus Cricetidae †Copemys †Eumys †Wilsoneumys Arvicolinae Arvicolini Arvicola †Mimomys Clethrionomyini †Allophaiomys †Altaiomys Alticola †Borsodia Caryomys Clethrionomys Craseomys Eothenomys †Pitymimomys †Prolagurus Dicrostonychini Dicrostonyx †Predicrostonyx Ellobiusini Bramus Ellobius Lagurini Eolagurus Lagurus Lemmini Lemmus Myopus †Plioctomys Synaptomys †Tobienia Microtini Alexandromys Chionomys Hyperacrius Lasiopodomys Lemmiscus Microtus Mictomicrotus Neodon Proedromys Stenocranius Volemys Ondatrini †Cosomys Neofiber †Ogmodontomys Ondatra Pliophenacomyini Arborimus Phenacomys Pliomyini Dinaromys †Pliomys Cricetinae Allocricetulus †Apocricetus Cansumys †Collimys †Cricetinus †Cricetulodon Cricetulus Cricetus Mesocricetus †Neocricetodon Nothocricetulus Phodopus †Rotundomys †Symmetrodontomys Tscherskia Urocricetus †Democricetodontinae Democricetodon Karydomys Spanocricetodon Neotominae †Protorepomys †Tsaphanomys Baiomyini Baiomys Scotinomys Neotomini Hodomys Nelsonia Neotoma Xenomys Ochrotomyini Ochrotomys Reithrodontomyini Habromys Isthmomys Megadontomys Neotomodon Onychomys Osgoodomys Peromyscus Podomys Reithrodontomys Sigmodontinae †Cordimus Juliomys †Megaoryzomys Oryzomyalia Abrotrichini Abrothrix Chlelemys Geoxus Notiomys Akodontini Akodon Bibimys Blarinomys Brucepattersonius Deltamys Juscelinomys Kunsia Lenoxus Necromys Neomicroxus Oxymycterus Podoxymys Scapteromys Thalpomys Thaptomys Ozyzomyini Aegialomys Amphinectomys Cerradomys Drymoreomys Eremoryzomys Euryoryzomys Handleyomys Holochilus Hylaeamys Lundomys †Megalomys Melanomys Microakodontomys Microryzomys Mindomys Neacomys Nectomys Nephelomys Nesoryzomys Noronhomys Oecomys Oligoryzomys Oreoryzomys Oryzomys Pseudoryzomys Scolomys Sigmodontomys Sooretamys Tanyuromys Transandinomys Zygodontomys Phyllotini Andalgalomys Andinomys Auliscomys Calassomys Calomys Chinchillula Eligmodontia Euneomys Galenomys Graomys †Ichthyurodon Irenomys Loxodontomys Neotomys †Olympicomys Phyllotis Punomys Reithrodon Salinomys †Tafimys Tapecomys Thomasomyini Abrawayaomys Aepeomys Chilomys Delomys Phaenomys Rhagomys Rhipidomys Thomasomys Wilfredomys Wiedomyini †Cholomys Wiedomys Sigmodontalia Ichthyomyini Anotomys Chibchanomys Daptomys Ichthyomys Neusticomys Rheomys Sigmodontini †Prosigmodon Sigmodon Tylomyinae Nyctomyini Nyctomys Ototylomys Tylomyini Otonyctomys Tylomys Muridae Deomyinae Acomys Deomys Lophuromys Uranomys Gerbillinae Ammodillus Desmodilliscini Desmodilliscus Pachyuromys Gerbillini Brachiones Dipodillus Gerbillus Meriones Microdillus Psammomys Rhombomys Sekeetamys Gerbillurini Desmodillus Gerbilliscus Gerbillurus Tatera Taterillini Taterillus Leimacomyinae Leimacomys Lophiomyinae Lophiomys Murinae †Alormys †Coryphomys Hadromys †Hoojieromys †Milimonggamys †Rakasamys †Spelaeomys Vernaya Apodemini Apodemus †Rhagamys Tokudaia Arvicanthini Aethomys Arvicanthis †Canariomys Dasymys Dephomys Desmomys Golunda Grammomys Hybomys Lamottemys Lemniscomys †Malpaisomys Micaelamys Mylomys Oenomys †Parapelomys Pelomys Rhabdomys †Saharamys †Saidomys Stochomys Thallomys Thamnomys Typomys Hapalomyini Hapalomys Hydromyini Anisomys Apomys Archboldomys Baiyankamys Brassomys Chiropodomys Chiruromys Chrotomys Coccymys Conilurus Crossomys Haeromys Hydromys Hyomys Leggadina Leporillus Leptomys Lorentzimys Macruromys Mallomys Mastacomys Melomys Mesembriomys Microhydromys Mirzamys Notomys Parahydromys Paraleptomys Paramelomys Pogonomys Protochromys Pseudohydromys Pseudomys Rhynchomys Solomys Soricomys Uromys Xeromys Zyzomys Malacomyini Malacomys Millardini Cremnomys Diomys Madromys Millardia Pithecheir Pithecheirops Murini Mus Otomyini Myotomys Otomys Parotomys Phloeomyini Batomys Carpomys Crateromys Musseromys Phloeomys Praomyini Chingawaemys Colomys Congomys Heimyscus Hylomyscus Mastomys Montemys Myomyscus Nilopegamys Ochromyscus Praomys Serengetimys Stenocephalemys Zelotomys Rattini Abditomys Anonymomys Bandicota Berylmys Bullimus Bunomys Chiromyscus Crunomys Dacnomys Diplothrix Echiothrix Eropeplus Halmaheramys Hyorhinomys Kadarsanomys Komodomys Lenomys Lenothrix Leopoldamys Limnomys Margaretamys Maxomys Melasmothrix Micromys Nesokia Nesoromys Niviventer Papagomys Palawanomys Paruromys Paucidentomys Paulamys Rattus Saxatilomys Sommeromys Srilankamys Sundamys Taeromys Tarsomys Tateomys Tonkinomys Tryphomys Waiomys Vandeleurini Vandeleuria †Pseudocricetodontinae Adelomyarion Cincamyarion Heterocricetodon Latocricetodon Lignitella Kerosinia Oxynocricetodon Pseudocricetodon Nesomyidae Cricetomyinae Beamys Cricetomys Saccostomus Delanymyinae Delanymys Dendromurinae Dendromus Dendroprionomys Malacothrix Megadendromus Prionomys Steatomys Mystromyinae Mystromys Nesomyinae Brachytarsomys Brachyuromys Eliurus Gymnuromys Hypogeomys Macrotarsomys Monticolomys Nesomys Voalavo Petromyscinae Petromyscus

• Onychomys
• Rodents of the United States
• Taxa named by Spencer Fullerton Baird