Family comparisons
Shrews are small mammals with short legs, a long flexible nose, small ears, and tiny eyes. From van Zyll de Jong (1983): "Most soricids are terrestrial, some are semi-fossorial (Cryptotis, Blarina), and others are adapted to a semi-aquatic way of life (e.g. Sorex palustris). Shrews are active day and night and in all seasons. They are chiefly insectivorous; the large species, to some extent are also carnivorous and some are known to eat seeds seasonally. The semi-aquatic forms are more or less piscivorous."
The skull is recognized by an elongated rostrum (snout); lack of zygomata (or zygomatic arches); first incisor enlarged; tympanic bone is a simple ring; and lack of auditory bullae (Hoffmeister, 1986). This family includes the the smallest terrestrial mammals and the only venomous mammal in North America, Blarina brevicauda. Four genera are represented within the family Soricidae in the United States and all are within the subfamily Soricinae, the red-toothed shrews: Blarina, Cryptotis, Notiosorex, and Sorex.
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Northern Short-tailed Shrew (Blarina brevicauda), the largest shrew in North America. Image by Gilles Gonthier. -
Notiosorex observed by Naturegirlkh. -
Sorex observed by Asmedley. -
Lateral view of the skull of Blarina brevicauda, showing an elongated rostrum, red-tipped teeth, and enlarged first incisors. -
Lateral view of the skull of Cryptotis parvus, showing an elongated rostrum, red-tipped teeth, and enlarged first incisors. -
Lateral view of the skull of Notiosorex crawfordii, showing an elongated rostrum, red-tipped teeth, and enlarged first incisors. -
Lateral view of the skull of Sorex monticolus, showing an elongated rostrum, red-tipped teeth, and enlarged first incisors. -
Top (dorsal) view of a Sorex skull showing the location of the missing zygomata. All soricids lack zygomata. -
Tympanic rings (bones) on underside (ventral side) of the skull of Sorex monticola, which are characteristic of members of the family Soricidae
From Naughton (2012): "Talpids (members of the family Talpidae) in the United States are dark gray or blackish animals with fusiform bodies; short appendages; manus (hand) rotated so palm faces outward; entirely white teeth; the skull is compressed dorsoventrally with a long rostrum; complete auditory bullae; complete but weak zygomata."
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Townsend's Mole (Scapanus townsendii), the largest mole in North America. -
Star-nosed Mole (Condylura cristata), showing its unique star nose. This is the only species with a star-shaped nose. -
American Shrew Mole (Neurotrichus gibbsii), the smallest species of mole in the Americas. Notice the small size and relatively long and hairy tail. -
Dorsal view of the skull of a Townsend's Mole (Scapanus townsendii), the largest mole in North America. -
Lateral view of the skull of a Townsend's Mole (Scapanus townsendii). -
Lateral view of the skull of a Star-nosed Mole (Condylura cristata).
Cricetidae is a large and diverse family of rodents and the second largest family of mammals. It includes true hamsters, voles, lemmings, muskrats, and rats and mice native to the Americas. The largest member of this family is the muskrat (Ondatra zibethicus). The smallest member of Cricetidae is the Northern Pygmy Mouse (Baiomys taylori).
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Common Muskrat (Ondatra zibethicus), the largest member of the family Cricetidae. -
Northern Pygmy Mouse (Baiomys taylori), the smallest member of the family Cricetidae. -
Northern Bog Lemming (Mictomys borealis) -
Bryant's Woodrat (Neotoma bryanti) -
Fulvous Harvest Mouse (Reithrodontomys fulvescens) -
Tawny-bellied Cotton Rat (Sigmodon fulviventer) -
Nearctic Collared Lemming (Dicrostonyx groenlandicus) -
Salt-marsh Harvest Mouse (Reithrodontomys raviventris)
The largest family of rodents and of mammals.
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Brown Rat (Rattus norvegicus) -
Roof Rat (Rattus rattus) -
House Mouse (Mus musculus)
From Hoffmeister (1986): "Relatively small-bodied rodents with long tails, most modified for jumping, with hind limbs elongated and forelimbs shortened, cheek pouches fur-lined and open externally, interparietal reduced, auditory bullae greatly inflated, incisors thin and compressed, no post-orbital process." Except for spiny pocket mice (Heteromys), heteromyids have grooved upper incisors. Five genera can be found in the United States: Chaetodipus, Dipodomys, Heteromys, Microdipodops, and Perognathus.
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Giant Kangaroo Rat (Dipodomys ingens), the largest species of Heteromyidae in North America -
Silky Pocket Mouse (Perognathus flavus), the smallest species of Heteromyidae in North America -
Merriam's Kangaroo Rat (Dipodomys merriami) -
Hispid Pocket Mouse (Chaetodipus hispidus) -
Dark Kangaroo Mouse (Microdipodops megacephalus) -
Mexican Spiny Pocket Mouse (Heteromys irroratus) -
Reduced interparietal, shown in the Ord's Kangaroo Rat (Dipodomys ordii) -
Inflated auditory bullae, shown in the Ord's Kangaroo Rat (Dipodomys ordii) -
Greatly inflated auditory bullae in the Pallid Kangaroo Mouse (Microdipodops pallidus) -
Fur-lined cheek pouches in the Plains Pocket Mouse (Perognathus flavescens). Arrow points to the inside of one of the fur-lined cheek pouches, which can be expanded greatly to accommodate and transport seeds.
Members of the family Zapodidae (jumping mice) have elongated hind limbs, remarkably long tails that are not well-haired (lack crests and tufts), dorsal coloration that ranges from dull yellow to bright yellowish orange with a darker mid-dorsal stripe, and a white venter. The upper incisors are grooved. Their skulls can be recognized by the presence of three or four cheekteeth.
The family Zapodidae contains two genera: Napaeozapus and Zapus. Napaeozapus typically have white-tipped tails whereas Zapus do not. Species in the genus Zapus have four cheekteeth, while species in the genus Napaeozapus have three.
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Northern Meadow Jumping Mouse (Zapus hudsonius) observed in the United States by Josh Emm. -
Northern Pacific Jumping Mouse (Zapus trinotatus) shown, representing members of the genus Zapus. Zapus typically lack a white tip at the end of the tail. -
Western Woodland Jumping Mouse (Napaeozapus abietorum) shown, representing members of the genus Napaeozapus. Napaeozapus typically have a white-tipped tail. -
Cheekteeth (molariform teeth) of Zapus -
Cheekteeth (molariform teeth) of Napaeozapus