World_of_Animals_Issue_46_2017

Leaf-cutter ants
Leaf-cutter ant
Atta cephalotes
class Insecta
territory Central and South
America
Diet Fungus
Lifespan 1-2 years (worker
ant); 10-15 years (queen)
adult weight 1-5mg
conservation status
NOT CLASSIFIED
Below Highly in tune with the fungus
they cultivate, leaf-cutter ants will stop
collecting a certain plant species if the
fungus releases toxic chemical signals
Ant anatomy
Leaf-cutter ants are highly adapted
for foraging on a colossal scale
Wings
A small selection of female
and male leaf-cutter ants
will develop wings during
the mating season to
allow the nuptial flight, or
revoada, to take place.
Size variation
These ants range in size from
the 2mm (0.07in) length of the
minim ants to the 22mm (0.8in)
length of the queen of the colony.
Their size determines their role
and function within the colony.
chemical signals
The ants leave pheromone trails
to good sources of vegetation for
other worker ants to follow. They
also let off chemical signals when
faced with danger, signalling for
other ants to defend the colony.
triggering a chain reaction that spreads rapidly through
the colony.
But a leaf-cutter ant’s most prized tool are its powerful
jaws and incredible strength. As their name suggests, leafcutter
ants use their jaws and mandibles to cut through
leaves, and most of their head is filled with the muscles
that close the jaws, but this is not for the purpose of
eating. A common misconception is that these ants eat
the leaves they cut. In fact, the ants cut the leaves and,
using the spines on the back of their thorax, carry them
home. Here, the leaf segments are cut into smaller pieces
and allowed to decompose. It is this fungus that the
ants feast on, making leaf-cutter ants the only creatures
on Earth, aside from humans, that grow and farm other
creatures. But with approximately 8 million ants in a
colony, that requires the decomposition of a lot of leaves,
and a single colony can strip a tree bare in just one day.
Similar to human societies, leaf-cutter ant colonies
are highly complex and intricate structures. Their
underground nests can be up to nine metres (29.5 feet)
deep and cover an area one acre (0.4 hectares) in size,
with some sub-entrances found 80 metres (262.4 feet)
away. The central mound can be 30 metres (98.4 feet)
wide and features complex tunnels and ventilation
chambers. These are carefully positioned to remove
poisonous carbon dioxide produced by the fungus
garden and to allow fresh air inside the nest.
With millions of inhabitants to keep in line,
colonies are ordered into castes, with each
ant having a crucial role within the nest. The three main
castes are mostly based on size and consist of the queen,
workers and soldiers, which are all female. The males are
purely there to breed with the queen.
Larger worker ants go out foraging, harvesting the
leaves with their strong jaws and carrying them back
to the nest. But they are often working in tandem with
tiny hitchhikers. The smallest leaf-cutter ants, known as
minims, will climb onto the leaves as they are being carried
and decontaminate them before they reach the fungus
garden, as well as feeding on the leaf sap. The minims also
protect the larger worker ants, often sitting on their backs
to ward off parasites such as phorid flies, which lay their
eggs in the crevices of the worker ants’ heads.
Medium-sized worker ants tend to the fungus garden,
care for the larvae and excavate tunnels within the colony,
while a special caste of worker ants is responsible for
waste management alone, shuffling the waste around
to help with decomposition. Sadly, these ‘rubbish’ ants
are exiled from the colony as they are often riddled with
disease and have shorter lifespans, and if they try to leave
the rubbish dump, other ants will force them back or even
kill them, showing how the success of a colony is in each
ant knowing its place within the workforce – an ability
they are born with. As each ant is so dedicated to its job
within the colony, leaf-cutter ants display the ultimate form
of teamwork; they are able to feed each other through a
second ‘social’ stomach, where they store undigested food
in a process known as trophallaxis.
“Similar to human societies,
leaf-cutter ant colonies
are highly complex and
intricate structures”
Super strength
Leaf-cutter ants have
phenomenal strength and
are able to cut, manoeuvre
and carry leaf segments
that are extremely heavy
in relation to their size.
Strong jaws
Leaf-cutter ants have extremely
strong jaws for cutting through
vegetation, which vibrate at 1,000
times per second. The muscles that
close the jaws are much stronger
than the muscles that open them.
antennae
Extendable and retractable
antennae are used for
identifying objects and
finding suitable vegetation
for cutting, as the eyesight of
leaf-cutter ants is fairly poor.
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