Tetraponera attenuata

Homology Weekly: Tentorial Pits

The anterior tentorial pits (arrows) in a <i>Tetraponera aethiops</i> worker (Scanning Electron Micrograph, Roberto Keller/AMNH)

The anterior tentorial pits (arrows) in a Tetraponera aethiops worker (Scanning Electron Micrograph, Roberto Keller/AMNH)

The head of an ant in frontal view has a couple of holes usually located in the area between the mouth and the place where the antennae are inserted. These holes look intriguing from the outside– Are they part of a sensing organ? Do they secrete a special chemical signal or defense substance through them? Are they use for breeding? The answer is more mundane than that. As I mentioned in an earlier post, most of what one sees in the outer surface of the arthropod’s exoskeleton does not have an external function, but is rather a symptom of the inside working in these wonderful machines. These particular holes mark the places where the cuticle invaginates to form the internal skeleton of the insect cranium known as the tentorium. The external holes produced by these invaginations are thus termed the tentorial pits.

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Homology Weekly: Arolium

Tuesday, March 24th, 2009 | Ants, Homology Weekly, Morphology | 3 Comments
Foot of a <em>Oecophylla smaragdina</em> worker. Pretarsal claws and manubrium in red; arolium in yellow; tarsi in green (Scanning Electron Micrograph, Roberto Keller/AMNH)

Foot of a Oecophylla smaragdina worker. Pretarsal claws and manubrium in red; arolium in yellow; tarsi in green (Scanning Electron Micrograph, Roberto Keller/AMNH)

This orchid-looking thing is really the foot of an ant. The large unfolded structure in between the powerful pair of claws is the adhesive organ of the foot called arolium (pl. arolia). It is basically a soft membranous bag folded into a suction cup that allows the ant to walk on vertical or upside down smooth surfaces.

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And as we discussed last semester, the Army Ants will leave nothing but your bones.
- Tom Waits

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