Docstoc

Army Ants (DOC)

Document Sample
Army Ants (DOC) Powered By Docstoc
					                                              Army Ants




   What eats every animal in its path, raids other ant colonies, and migrates to find more food? An army
ant colony! Army ants are amazing creatures! Not only have they founded nests, developed a social
hierarchy, and migrated to other areas, but they also have a very interesting life cycle and colony
structure.

Imagine being attacked by a pack of 50,000 wolves. That's how an insect that finds itself in the path of a
colony of army ants feels. These tiny soldiers are voracious predators. The driver ants of Africa and the
army ants from South America cling tightly to one another (in large groups of 10,000 to 500,000) as they
travel across the land looking for food and attacking any animals that get in their path. These vicious
creatures have been known to kill tarantulas, lizards, birds, snakes, pigs and sometimes animals as
large as horses. Usually larger animals can get away from the oncoming ant army, but if they are caught
off guard or sleeping, these could become "drive-through" rations for the hungry army.

A single colony — which may consist of more than 1 million ants — can eat 50,000 insects in a single
day, so it must continually migrate to find new sources of food. There are about 150 different kinds of
army ants traveling around Central and South America and the southern United States. In parts of South
America, army ants are welcome exterminators, providing free pest-control services without dangerous
insecticides. Villagers are reputed to willingly vacate their homes in the wake of an army ant raid,
returning afterward to completely insect-free houses.




NESTS

   Army ant colonies consist of the queen, the queen’s brood (her eggs), soldiers, and the workers.
army ants are nomadic, which means that they must make temporary nests as they travel. The nest is
made up of Army ants themselves. They form walls and fasten onto each other by using their mandibles
(jaws) and their claws. This way they can hang from a log or another surface, while the nest encloses
the queen and her brood. They are referred to as bivouacs, which is a cluster of ants. Chambers and
corridors do exist in army ant nests. Also, prey is being brought inside the nest and the eggs are being
transported to other areas in the nest as well.

HIERARCHY

   The main castes in an army ant hierarchy are queens, workers and soldiers. In
                                        The queen then lays
the hierarchy, the queen ant lays eggs the whole day.
up to as many as 30,000 or more eggs in two days.
The large soldiers focus on defense, the medium size workers do the foraging,
and the               smallest workers tend the queen’s brood. Since the workers in the colony are
sterile               females, they cannot lay eggs or start their own colonies.

                      MIGRATION

                            Because of their large colony size, army ants migrate in order to find food.
                        They may raid other colonies and capture slaves. During the nomadic phase,
                        army ants march at night and stop to camp in daylight. The colony starts its
           stationary phase when the need for food decreases. Then they make temporary nests, and
           change the nest everyday. Each of these rampages lasts for about seventeen days. Some say
that army ants may have a collective intelligence
   Army ants kill and eat up to 100,000 animals in a day. Together they can kill lizards, snakes,
chickens, pigs, goats, scorpions, and many other animals. They also climb trees and eat birds plus
insects that may live in trees.




DESCRIPTION

Like many other insects, the body of an army ant has a head, thorax and abdomen. The head has a
mouth, eyes and antennae. The mouth has two jaws called mandibles that are like scissors. Still, army
ants can only swallow liquids because the solids form a ball that the ant spits out. Unlike other ants,
army ants do not have compound eyes, but instead have single eyes (but they are still blind). Army ants
use their antennae to sense smell and touch. This is how they know which colony and nest they belong
to. They use their antennae to communicate as well. The thorax is connected to the head by joints called
nodes. The thorax is between the head and abdomen. It is connected to the abdomen by a narrow waist
called the petiole. The abdomen is in the shape of an oval. That is where the stomach, large intestine,
sting, etc. are located.
                                              Eciton burchelli soldier




                                      .




Army ants, the voracious predators of the jungle, march in long black columns that consume every living thing
in their path. Almost nothing can stem their onslaught except fire and broad expanses of water. Yet these
primitive creatures have a key weakness. Behaviorally, they are hard-wired to follow one another in rigidly
held ranks. When the ants encounter a barrier they cannot cross, the leader will veer off course to find a way
around the obstacle. The other ants always follow right behind. Occasionally, however, the leader will have to
make such a wide circuit that it ends up behind the last ant in the parade. At this point, its behavioral circuits
kick in and it is compelled to follow the caboose ant. The swarm is then locked into a circular path. As the ants
become hungrier, they march harder and faster, but can’t break out of the circle. Eventually, they starve and
die.

				
DOCUMENT INFO
Shared By:
Categories:
Tags:
Stats:
views:17
posted:12/13/2011
language:English
pages:3