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Odontomachus

Trapjaw ant (Odontomachus cf. hastatus); photographed in situ [1]

Having a sleek agile body plan, long legs, and an astonishingly quick bite, trapjaw ants (Odontomachus cf. hastatus) are one of my favorite neotropical ants. They are a nocturnal species, nesting in the roots of epiphytic bromeliads and emerging during crepuscular hours to hunt within a near radius of the colony. Odontomachus are relatively large ants with unforgiving mandibles and a sting, enabling them to individually subdue a variety of canopy-dwelling arthropods. However, many specialize on termites. In contrast to most ants which are entirely active foragers, Odontomachus is also an ambush predator. Much like the individual pictured above, workers will sit completely still with the mandibles positioned at 180 degrees. To adopt this posture, contractile muscles store energy gradually over the course of a few seconds. Long mechanosensory hairs protrude forward, and when contacted by a prey item, large sensory neurons trigger adductor muscles that disengage the mandibles and result in an instantaneous release— like removing the latch on a catapult. But the utility of trapjaws doesn’t end there. When approached by a predator, many trapjaw ants direct their strikes at the ground and launch themselves twirling into the air to escape. If the trapjaw ant is already physically engaged, the force can be applied on to the predator itself, resulting in both parties flying in opposite directions.

reserved for species that use stored muscular energy to generate speeds that far exceeds that of muscular control. In Odontomachus bauri, the mandibles snap for less than one fifth of a millisecond, but in that time reach speeds of 140 mph. By this definition, trapjaw ants are unable to halt their mandibles from shutting once the potential energy has been released, which excludes a variety of long-jawed ants (e.g., Harpegnathos, Myrmecia) from being considered trapjaws, and curious cases like the Dracula ant (Mystrium camillae) that use physical strain for elastic tension like a finger snap to earn the title of the fastest animal appendage known to date (>200 mph). A true trapjaw mechanism has still likely evolved dozens of times, within the Ponerinae (including Odontomachus), Myrmicinae, and in the Formicine Myrmoteras.

Repeated evolution of trapjaw mechanism in ants, from Larabee & Suarez, 2014 w/ photos by Alex Wild and AntWeb

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