Georgian Bay, in the northeastern part
of the lake, is a popular summer resort
area. Many tourists visit Georgian Bay
Islands National Park and the Thirty
Thousand Islands.
#More to explore
Great Lakes • Saint Lawrence River and
Seaway •Wyandot
Hussein, Saddam
#see Saddam Hussein.
Hydra
A hydra is a tiny animal that lives in
water. Hydras can regrow parts of their
bodies. They are named after an imaginary
creature from Greek mythology,
the nine-headed hydra. According to the
myth, this monster could grow two new
heads for each head that was cut off.
The real-life hydra is only about 1.2
inches (3 centimeters) long. It has a thin,
tubelike body with an opening at the
top. The opening is used both to eat
food and to get rid of waste. Long,
fingerlike tentacles grow around this
opening. The hydra uses its tentacles to
Lake Huron
was the first of
the Great
Lakes to be
visited by
Europeans.
BRITANNICA STUDENT ENCYCLOPEDIA Hydra 103
sting and paralyze its food. It eats tiny
animals.
The hydra can reproduce in two ways. It
can release eggs, which are then fertilized
in the water. The fertilized eggs grow
into new hydras. It can also reproduce
by budding. During budding, a hydra
grows a new body that finally nips off at
its base to make a new hydra.
Hyena
Hyenas are mammals of Africa and Asia.
They look something like dogs, but they
are not related to them. There are three
species, or types, of hyena: spotted,
striped, and brown. The spotted hyena
is known for its hunting cry, which
sounds like human laughter.
Hyenas are gray, brown, or yellowish.
Some have stripes or spots. Their front
legs are longer than their hind legs. The
spotted hyena is the largest species.
Female spotted hyenas are larger than
males. Females measure about 6 feet
(1.8 meters) long and weigh 175 pounds
(80 kilograms).
Hyenas have large heads with jaws and
teeth that are strong enough to crush
bones. Their excellent senses of hearing
and smell help them to find prey.
Hyenas live on dry grasslands with few
trees. They find shelter in caves or
empty underground tunnels, or
burrows. Hyenas are most active at
night. They live alone or in packs.
Spotted hyenas may form packs of 80
or more animals. Within groups spotted
hyenas communicate using signals and
sounds.
Hyenas are often seen waiting to feed on
what is left of a zebra or gazelle after lions
are done with it. Sometimes the prey
animal was actually killed by the hyenas
and then stolen by the lions.
#More to explore
Mammal
Spotted hyenas make many sounds, including
yells, giggles, and whoops. These
sounds may travel for several miles.
A new hydra can be seen budding from an
existing one. The new hydra is a smaller
and paler version of the first one.
104 Hyena BRITANNICA STUDENT ENCYCLOPEDIA
The Iditarod is a dogsled race
that takes place in Alaska each
year.
(See Iditarod.)
The Inca Empire included about
12 million people at its peak in
the early 1500s.
(See Inca.)
There are about 1 million types
of insect. They make up about
75 percent of all animals.
(See Insect.)
German engineer Rudolf Diesel
developed the diesel engine in
about 1890.
(See Internal-Combustion Engine.)
E-mail was invented in 1971.
(See Internet.)
A human’s small intestine is
about 22 to 25 feet (6.7 to 7.6
meters) long.
(See Intestines.)
II ii
Ibis
Ibises are birds with long, slender bills
that curve downward. They are wading
birds, meaning that they typically walk
through shallow water when feeding.
They usually feed, fly, and breed in huge
groups. The ancient Egyptians believed
that one particular type of ibis was holy.
After these birds died, the Egyptians
carefully preserved them as mummies.
There are about 20 species, or types, of
ibis. They belong to a scientific family
that also includes spoonbills. As its name
suggests, a spoonbill has a beak with a
rounded tip that looks like a spoon.
Ibises are also related to herons, storks,
and flamingos.
Ibises are found in most of the world’s
warm and hot regions. They tend to live
near shallow bodies of water, including
marshes, lagoons, lakes, and bays.
Ibises are usually about 22 to 30 inches
(55 to 75 centimeters) long. Their legs,
neck, and bill are long. The tail is short.
Most ibises have white, black, or brown
feathers. However, the scarlet ibis is
bright red. The hadada ibis has greenish
feathers, and the glossy ibis has dark
brown and shiny purple feathers. In
many ibises part of the face lacks feathers
but has brightly colored skin.
An ibis uses its long bill to search the
mud for food. Ibises eat such animals as
shellfish, insects, worms, and small fish.
#More to explore
Bird • Flamingo • Heron • Mummy
• Stork
Icarus
#see Daedalus.
Ice Age
An ice age is a time when thick ice
sheets called glaciers cover huge areas of
land. An ice age may last for millions of
years and can cause big changes to
Earth’s surface. Ice ages have happened a
number of times throughout Earth’s
history.
The Latest Ice Age
The latest ice age began more than 1.8
million years ago and ended about
10,000 years ago. During this period
huge glaciers formed and spread south
from the North Pole. Several times these
glaciers partly melted so they covered
