Monday, November 12, 2007

Crustacean Mitigation:
How the invertebrate lobster uses magnetic fields for orientation.

Animals use a variety of mechanisms in order to move around in space. Many vertebrates use odor, sun and magnetic compasses in order to perceive direction. One of the best examples of this is with the homing pigeon, which uses the Earths magnetic field in order to orient itself on its journey. If these sophisticated vertebrates have evolved these sensory systems, what have the lowly invertebrates devised to cope with their environment? The answer for one invertebrate, the Caribbean Spiny Lobster, might be surprising.

Recently researchers from UNC noticed something peculiar with the Caribbean Spiny Lobster, a crustacean indigenous in the western Atlantic( around Brazil), the fact that it seemed to possess some form of navigation capabilities that allowed it to return to its “home” when displaced by researchers. Tests of this particular lobster documented its exceptional navigation but what did it use? When the researchers caught a lobster and transported it in a convoluted trip to another spot, in order to “try” to disorient the lobster, they noticed that the tethered lobsters continuously oriented in the compass direction in which they were taken from. The theory was that the lobsters used the Earths magnetic field in a manner similar to that of the Homing Pigeon, so to test this theory they caught over one hundred lobsters and performed a series of experiments. Some of the captured lobsters were transported to another location and simply tethered to see which direction they would orient while other lobsters were placed into an “induced” magnetic field around where they were tethered. The tests conclusively showed that the lobsters tethered with the “induced” magnetic field were incapable of orienting to the location where they were displaced from while their brethren without the induced field were successfully able to orient toward their home. Their findings proved that the Caribbean Spiny Lobster did possess a “magnetic compass” similar to that of the homing pigeon. So far, only the spiny lobster has been shown to posess the magnetic compass, but other crustaceans have yet to be fully studied, so the jurys out. Apparently invertebrates are more sophisticated than we might have perceived :-)

Posted by Doug Zelisko (8)


At 9:49 PM, Blogger PWH said...

Wow, what a find. It does sound familiar, the experiment, I mean, to things we've discussed in class. Just that weird attachment to a cardinal direction in some animals...
Anyhow, I guess there are only a few ways to test that kinda stuff.

-Posted by Brad Garvey

At 9:49 PM, Anonymous Caroline Collins said...

Nice find for your article, it was intriguing. It would be interesting to find out what causes the sense of the magnetic force in the lobster and pigeon. Also I'd like to find out if this sense of navigation is present in other species of lobsters.


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