Scientists
don't know why the ant is covered in doorknob-like lumps.
Every
queen needs a crown. For the queen ant Monomorium triviale, that crown bursts
and bubbles out of her head, back and abdomen while she's still a larva —
leaving worker ants little confusion about who's the boss, even when the boss
is a baby.
M.
triviale are amber-colored ants native to China, Japan and South Korea. The
queen ants of the species can produce offspring by laying unfertilized eggs —
no males necessary — in a process called thelytokous parthenogenesis. In fact,
a new study published March 3 in the journal Zootaxa points out, no male M.
triviale have ever been identified; all known M. triviale ants fit into two
categories: sterile female workers and fertile queens.
In
their new study, researchers wanted to better understand the differences
between these two ant classes, starting at the earliest larval stages. The team
collected some M. triviale nests from a thicket in the suburbs of Kyoto, Japan,
then transferred the immature colony members to artificial nests in a
laboratory. There, the researchers studied the ant larvae using several types
of high-definition microscopy.
As the worker and queen ants developed, they
periodically shed their exoskeletons, taking on strange new forms (or
"instars") with every molting. Both queens and workers started as
oblong blobs, before developing mouthparts and tiny, spiky hairs along their
bodies within a few days of hatching, the researchers wrote.
As the worker and queen ants developed, they
periodically shed their exoskeletons, taking on strange new forms (or
"instars") with every molting. Both queens and workers started as
oblong blobs, before developing mouthparts and tiny, spiky hairs along their
bodies within a few days of hatching, the researchers wrote.
But in her final larval form, the queen ant pulled
off a look unlike any other. Her body had gone almost completely hairless, the
team found, and had instead sprouted 37 doorknob-like lumps, or "tubercles"
all along its length, giving her a look something like an alien plushie doll,
or a Panic Pete squeeze toy from a parallel universe.
When the researchers probed the interior of these
tubercles, they found that the lumps were made of extended skin and cuticle,
and they were about twice as thick as any other part of the queen's body. The
lumps contained no muscle, ducts or specialized parts, raising the question:
What are the ant queen's fleshy lumps actually good for?
The study authors couldn't say for sure, but they
pointed to five possible explanations from a 1976 paper whose authors had
looked at the morphology of various ant larvae. The structures could help
support the larvae's bodies, allow them to cling to nest ceilings or walls, or
they might help queens defend against cannibal attacks from other larvae, the
researchers wrote.
Alternatively, the lumps could be involved in
feeding, possibly being used to hold food to the larva's body surface, or to
help pass food between larvae.
"The function of queen-specific tubercles of
the M. triviale larvae is still unclear at this time," the authors of the
new study wrote in the paper. "Behavioral observations of the interaction
between the workers and the queen larvae… will help us understand the hidden
but essential roles larvae play in complex ant societies."
It's a lot of look, but M. triviale's larva queens
pull it off. Now, scientists just need to figure out why.
European Journal of Case Reports and Clinical Images is an international open-access journal publi
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