Beetles Rule!
There are more than 800,000 species of insects on earth, more than
all the other plants and animals combined. Of this great number of
insects, nearly half are beetles, and there are probably 100,000
species of horned beetles. Look for them! Unlike other insects, beetles
(Order Coleoptera) have a pair of leathery protective wings
called elytra that cover their
membranous flight wings. During flight, the elytra are spread apart and
the
two flight wings are unfolded and extended. Beetles come in a variety
of
shapes and colors, from huge horned beetles resembling a miniature
rhinoceros.
to small red "ladybugs" and metallic green fig beetles and
lightning
beetles that glow in the dark. The Biggest Beetle
Beetles range in size from less than a millimeter (1/100 of an inch) to
tropical giants up to six inches long. The largest giants may weigh 40
million times more than their lilliputian relatives. One of the most
amazing
is the Hercules beetle (Dynastes hercules), native to the rain
forests of Costa Rica (see photo). This spectacular beetle, 65-170mm
long, has
two enormous curved horns and looks like a creature from the age of
dinosaurs.
The Strongest Creature
The strongest creature on earth is said to be a harmless bug that fits
in the palm of your hand. It's the rhinoceros beetle, which can carry
850 times its own weight. That would be the equivalent of a man
carrying 80 family-sized cars on his back. The rhinoceros
beetle is named because it has horns on its head, very much like the
rhinoceros does. Scientists believe that the beetle has become so
strong to be able to forage through heavy litter on the jungle floor
and dig its way to safety. Using its horns it can dig its way out of a
sticky situation by burying itself underground, escaping danger. Adult
rhino beetles eat rotting fruit and sap; in spite of their size, they
don't eat very much. The larvae, on the other hand, eat a great deal of
rotting wood or the compost in which they live.In other words, they are
champion recyclers. Despite their fierce appearance, they are all
totally harmless: they cannot bite or sting or hurt you with their
horns. Unlike most other beetles, both males and females have horns.
Rhinoceros beetles belong to the family Scarabaeidae which is
the fifth largest family of beetles, with nearly 30,000 species known!
And there are even more species that aren't yet known.
Why do Horned Beetles have Horns?
The most common explanation appears to be that they are used for
fighting -- males battle for mates, or defend their chosen female's
tunnel with their horns, thus passing on their genes. Even without
fighting, females may pick the males with the longest horns. However,
within a species, the size of
the horns can vary widely. One study found that the primary influence
on
the size of the horns of fungus beetles is the environment in which a
beetle is nurtured -- notable the kind of fungus the larvae eat. A similar result holds
for dung beetles (Onthophagus), who use their horns to
manipulate dung balls. Some dung beetles have large horns, some small,
and some none at all. Dung beetle horns have been shown to operate as a
tool in intrasexual combat, and the existence of a "hornless" class
suggests
that these smaller males may engage in an alternate, less aggressive
behavior. Studies of the horned beetles have shown that these two
morphs have different
types of reproductive behavior. Large, horned beetles are found
guarding
entrances of tunnels that contain females. Small, hornless males adopt
a
sneaking behavior by digging new tunnels that intercept the guarded
tunnels,
remaining undetected. Perhaps
one in 10 of these clandestine quests actually succeed, but to the
victors go the
genetic spoils, especially in the beetle world.
The rhinoceros
beetle is named because it has horns on its head, very much like the
rhinoceros does. Scientists believe that the beetle has become so
strong to be able to forage through heavy litter on the jungle floor
and dig its way to safety. Using its horns it can dig its way out of a
sticky situation by burying itself underground, escaping danger. Adult
rhino beetles eat rotting fruit and sap; in spite of their size, they
don't eat very much. The larvae, on the other hand, eat a great deal of
rotting wood or the compost in which they live.In other words, they are
champion recyclers. Despite their fierce appearance, they are all
totally harmless: they cannot bite or sting or hurt you with their
horns. Unlike most other beetles, both males and females have horns.
Rhinoceros beetles belong to the family Scarabaeidae which is
the fifth largest family of beetles, with nearly 30,000 species known!
And there are even more species that aren't yet known.
A similar result holds
for dung beetles (Onthophagus), who use their horns to
manipulate dung balls. Some dung beetles have large horns, some small,
and some none at all. Dung beetle horns have been shown to operate as a
tool in intrasexual combat, and the existence of a "hornless" class
suggests
that these smaller males may engage in an alternate, less aggressive
behavior. Studies of the horned beetles have shown that these two
morphs have different
types of reproductive behavior. Large, horned beetles are found
guarding
entrances of tunnels that contain females. Small, hornless males adopt
a
sneaking behavior by digging new tunnels that intercept the guarded
tunnels,
remaining undetected. Perhaps
one in 10 of these clandestine quests actually succeed, but to the
victors go the
genetic spoils, especially in the beetle world.