Senses in antennae

[DanInSD]

This is probably one for Dr. Roy.

I was watching a program on insects last night on Discovery, and they were talking about how different pairs of antennae have different types of receptors (chemoreceptors versus mechanoreceptors, for instance).

This made me think about stomatopods -- what senses do they have in their various antennae? I was watching my peacock exploring the tank this morning, and when she suspected a shell had something in it, she would put both large antennae on it, tapping and rubbing (this wasn't very efficient, as it turned out -- she did it on a live astraea snail and moved on). Obviously she was feeling for movement, but was there also "taste" (chemoreceptors) involved?

Also, do stomatopods have other special senses that we lack, like electrical detection ala the ampullae of Lorenzini in sharks?

Thanks,
Dan

[Pea-brain]

I would immagine that sound receptors and smell (chemoreceptors as you called them) would be included. Stomatopods recognize other individuals through smells. And when I make noises on the other side of the tank I see knives sometimes twitch his antennae. Or run if its loud

[Gonodactylus]

No magnetic or electrical senses that we know of, but that really has not been explored. In the visual world, they excel with the broadest range of spectral vision known in the animal kingdom as well as very sophisticated linear polarized light detection. We have just discovered another visual sense that is absolutely unique to stomatopods. Can't talk about that until the paper is published next summer.

As for chemosensory capabilities, both the antennules and the antennae receive information. The antennae seem to deal more with contact information (and perhaps mechanical), the antennules receive distance chemosenory inputs more like smell.

One of the more remarkable discoveries I've made about stomatopod was the ability to recognize and remember individual with whom they have interacted. They can remember another stomatopod for up to two or three weeks. That information is obtained by a comb of hairs located on the second (shortest) flagellum of the antennule (there are three terminal flagella). In some close up photos of stomatopods you can see these receptor setae arranged in a single row. We know that they are the ones involved because we can ablate them and the recognition behavior goes away. (We dip them in deionized water and the cell membranes rupture rendering the receptors non-functional. They regenerate in a week and are fully functional again.)

One sense that we know nothing about is hearing or pressure wave detection. Several stomatopods make sound, so I assume that there must be an "ear", but we don't know where it is. My bet is on the antennal scales. They are perfectly shaped and positioned to pick up - if not sound - pressure wave displacement.

So much we don't know about their sensory world - and every time we look, we find something unexpected.

Roy