(Courtesy of Alex Wild, copyright. Used with permission.) A Formica ant suspends a drop of aphid honeydew between her mandibles (which bristle with 7 or more teeth), as she drinks it.
An ant's many teeth
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JUNE 06, 2007
April Holladay, HappyNews Columnist

Q: How many teeth do ants have?
Hatheem, Colombo, Sri Lanka
A: How many teeth an ant has depends on which of the 12,000 ant species http://atbi.biosci.ohio-state.edu:210/hymenoptera/tsa.sppcount?the_taxon=Formicidae we're talking about. The creatures roam planet-wide, except for Antarctica and a few oceanic islands.
Early ants had only two teeth, but most modern ants have more — although some are "nearly toothless," emails entomologist Alex Wild http://www.myrmecos.net/contact.html of the University of Arizona.
In fact, although totally lacking teeth is a relatively rare condition, many ants do nearly lack teeth. Larger workers of "nearly toothless" species may have slight hints of teeth but smaller workers have none.
Most ants, though, have teeth. Larger ant species typically have more teeth than smaller ones, and the number varies from about two to at least eighteen teeth per mandible.
The teeth are made of the same tough stuff as an ant's exoskeleton. They look like, and are, extensions of the mandibles.
Some ants have many, sharp teeth to penetrate and hold a soft-bodied, squirmy insect long enough to sting it. But such teeth break when the mandibles snap together on a tough foe like a termite soldier. Ants after hard-bodied prey have blunt teeth, and crush the insect with a blow like a sprung trap from their quick-closing jaws.
Mandibles of some ants can slam shut in 0.3 ms, a thousand times faster than an eye blink, says neurobiologist Wulfila Gronenberg http://neurobio.arizona.edu/faculty/gronenberg/index.php?&index=0#pubs of the University of Arizona.
Few ants can exert enough jaw pressure to penetrate human skin. The painful 'bite' we feel is actually a venomous sting. An African driver ant, however, can bite with her sharp teeth hard enough to hurt a person badly. In fact, these fierce insects can swarm over a large mammal, and literally slice it to death. "The soldiers of the neotropical leafcutter ants can also easily break the skin with their bites," says Wild.
Further Reading:
Ant behavior by Alex Wild, Myrmecos.net
Ants of South East Asia, www.antbase.net
Trap-jaw mechanism by Wulfila Gronenberg, The Journal of Experimental Biology 199, 2021–2033 (1996)
Morphological and Functional Diversity of Ant Mandibles by Chris A. Schmidt, Tree of Life Web Project
The number of ants in the world, The Physics Fact Book
(Answered June 11, 2007)