disagree about the number of species (17 - 20) and genera (7 - 9) in this
family, but they are possibly the most similar of all extant mammals to
the very earliest placental mammals. They are found throughout Africa, Eurasia,
south-eastern Asia. Identifying features include their dental formula (i2-3/3,
c1/1, pm3-4/2-4, m3/3 = 36 - 44), complete zygomatic arch, eyes and ears
of moderate size, and plantigrade foot posture. In some species the anterior
incisors are enlarged. The upper molars are quadritubercular, while the
lower molars have well developed trigonids and talonid basins. Hedgehogs,
but not gymnures, are covered with sharp spines. By rolling into a tight
ball, many hedgehogs are able to protect vulnerable areas of the body from
predators. Lacking spines, gymnures emit a foul odour when threatened.
gymnures are diurnal, others are nocturnal. All hedgehogs are nocturnal,
resting during the day in a leaf nest or dry cavity. Some hedgehogs live
in burrows, and generally dig their own. Several species, and typically
Erinaceus europaeus, hibernate in the colder parts of their geographic range.
The heartbeat of E.europaeus drops from its normal 188 beats per minute
to 21 beats per minute during hibernation (Nowak 1991). All erinaceids feed
on insects and other invertebrates. Gymnures also include some plant matter
in their diet. Hedgehogs also consume a wide variety of foods, including
carrion, roots and fruit. Although terrestrial, erinaceids are good climbers
and can also swim. Echinosorex may be aquatic to some extent. Most have
one or two breeding seasons a year, and a litter size of one to seven.
Erinaceus europaeus (European Common Hedgehog)