Polyrhachis lamellidens

Evolutionary Adaptations


How has it adapted to its environment?

The Polyrhachis lamellidens has acquired many adaptive traits through its evolution that have permitted it to achieve great success in its environmental surroundings. The evolution of the large spines on the petiole and propodeum regions have provided these ants with an excellent defense structure in a very vulnerable area for the ant.  The propodeum is a very thin part of the ant that can easily be “sliced” by predators, which would result in a lethal injury to the organism.  The evolution of these large spines provides the organism with a means of defense to help prevent such an injury from occurring.

Evolution has also provided the Polyrhachis lamellidens with the ability to weave their own nests using larval silk.  This adaptation is an important means of survival for the organism, because it allows the ant to construct a safe and durable nest in the trunks of hollow trees.  The larval silk nest provides members of the colony with a safe place to live and the means to fit into its niche.

One of the structures that varies the most within the Formicidae are the mandibles.  The mandibles of the Polyrhachis lamellidens have evolved into fairly large triangular shapes.  This morphology is important to omnivorous ants, because they need to be able to grasp their food and squeeze the juices from it in order aquire nutrients.

Primary means of movement:

This organism is very motile and is able to move at a very fast pace relative to its size.  It is able to achieve such movement through the use of six legs that are attached to the thorax.  The legs of the Polyrhachis lamellidens are very long relative to its body size, which contributes to its ability to move so quickly.  The queen ants and the reproductive males are also able to move using a pair of wings during nuptial flight.

Sensing the Environment:

The two bent antennae located on the head region of the ant are its most important means of sensing the world around them.  The complex sensillum structures on the antennae allow the Polyrhachis lamellidens to use chemical signals as a way of achieving a greater level of organization in their colonies.  These chemical signals are vital to their survival as it allows them to detect predators and prey.  The antennae are also important in that they provide the ant with the ability to smell and detect sound.


The two compound eyes located on the head region also help the ant sense the environment.  These large eyes do not provide the ant with very good resolution, but they do give the ant an acute perception of movement with multiple images per eye.


Reacting to the Environment:

When the antennae and compound eyes are used in accordance with one another, this organism can be quite proficient in reacting quickly to its environment.  The antennae allow the ant to sense when a predator is approaching.  It then relies on the compound eyes for quick detection of that predator and a hopeful escape.

The antennae are also the reason for its ability to survive and live in colonies.  Worker ants react to signals given by the queen to build a nest or to get food.  Without the antennae the ant would not be able to detect or react to various stimuli in the environment and within its colony.


How do its structures relate to their function?

The antennae are long and slender in order to achieve maximum surface area.  When the surface area of the antennae is greater, the capacity to sense the environment increases.  The antennae are so vital to the survival of this organism that they have developed combs on the “wrists” of their appendages.  These comb structures allow them to keep their antennae clean and functioning at their full capacity.

As mentioned above, the compound eyes do not provide the organism with images of great resolution.  The compound eyes of the ant take up a much greater percent of the head than the eyes of humans and other vertebrates do.  The  compound eyes are not all that impressive compared to most vertebrates.  This is the reason why increasing the surface area of their eyes was a necessary evolutionary step.  The increased surface area of the compound eyes allow the organism to possess a more effective sense of sight.

The structure of the spines on the petiole and propodeum are fairly obvious in their function.  The spines are very long and sharp which allow for effective protection against possible predators.  The two spines located on the petiole are the longest and sharpest, because the area around the petiole is where this ant is most vulnerable to an attack.

Watch how the Polyrhachis lamellidens uses its antennae to sense the environment in this cool video! (skip to 0:30 to see antennae use)


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