The feared and fascinating Jack Jumper Ant - the metazoan with the lowest possible number of chromosomes
The Australian Jack Jumper Ant, Myrmecia pilosula (Formicidae), with its 12 mm length, large eyes, and long mandibles with teeth, is an aggressive ant with a very potent sting.
The sting is not severe (in terms of pain), but this ant is responsible for greater than 90% of Australian ant venom allergy. In Tasmania stings by M. pilosula (and possible the Inchman ant, M. forficate) caused 21-25% of the 324 cases of anaphylaxis treated with adrenaline in the Royal Hobart Hospital Emergency Department between 1990 and 1998, compared with 13% caused by honeybee stings.
Moreover, what I personally find fascinating is the fact that ants of the Myrmecia pilosula species complex include some individuals with the lowest possible metazoan chromosome number of 2n = 2, although others in this cluster of sibling species have much higher numbers, the known maximum being 2n = 32.
If we also consider that males are haploid (they have a single set of chromosomes in the nucleus of their cells), as in other Hymenoptera, the somatic cells of males contain only a single chromosome.
Other common names: Jumper Ant, Hopper Ant, Jumping Jack, Bull Ant.
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Photo: ©Arthur Chapman
Locality: Falcons Lookout Track, Werribee Gorge State Park, near Ballan, Victoria, Australia