Order Insectivora is comprised of a wide variety of mammals, from the pygmy shrew to the spiny hedgehog. Insectivores are named after their tendency to eat insects, but they will also eat other invertebrates such as worms and even some vertebrates (fish, lizards, etc). Insectivores are small and rodent-like in appearance. The pygmy white-toothed shrew is the world's smallest mammal.
Insectivores are considered to be "primitive" mammals because they are missing some factors present in more "advanced" mammals like the primates. For example, they have a flat brain case and a smooth brain, compared to the curved brain case and more ridged brain of the primates. Most insectivores lack a separate opening for the genitals and anus, and instead have a cloaca, which serves as the genital, urinary, and fecal system.
Insectivores vary greatly in appearance. They typically have a long snout, as evidenced by most moles and shrews and solenodons. Some are covered in a mouse-like fur with a hairy, smooth tail, others are covered in spines and lack tails entirely. Shrews, which are the most mouse-like in appearance, can be distinguished from mice by their long snout and their lack of constantly growing incisors.
Insectivores have an excellent sense of smell and touch, but have poor senses of sight and hearing. They live in a wide variety of habitats, from streams to open meadows to deep underground. They are absent from Australia and most of South America. There are 419 species in 6 families:
Solenodontidae (solenodons) 3 spp
Tenrecidae (tenrecs) 24 spp
Chrysochloridae (golden moles) 18 spp
Erinaceidae (hedgehogs, gymnures) 21 spp
Soricidae (shrews) 313 spp
Talpidae (moles) 40 spp
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