60-Second Science

Box Jellyfish Eyes Aim at the Trees

Four of a box jellyfish's 24 eyes always aim at the tree canopy, which tells them where their favorite food is. Steve Mirsky reports














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Box jellyfish have it over the rest of the jellyfish world—they have true eyes, featuring corneas, lenses and retinas. They have a more sophisticated nervous system too. They still don’t have a real brain, but those eyes enable them to actively hunt prey. Other jellyfish just drift and hope. Well, not really hope, because you can’t do that without a brain.

Anyway, it’s been long known that box jellies had eyes, 24 in fact, of four different types. But now researchers have found that four of those eyes just look up, and out of the water. The work appears in the journal Current Biology. [Anders Garm, Magnus Oskarsson and Dan-Eric Nilsson, "Box Jellyfish Use Terrestrial Visual Cues for Navigation"]

The studied jellies live in mangrove swamps and the studied eyes are always aimed at the tree canopy. By tracking the canopy the jellies can navigate to their preferred spots—where their favorite food, small crustaceans called copepods, are plentiful.

Their various eyes show that the jellies evolved a clever strategy. Rather than a single set of peepers that collect info for processing by a big brain, box jellies have different eye types responsible for informing different behaviors, with no brains. More evidence that it can be a mistake to overthink a problem.

—Steve Mirsky

[The above text is an exact transcript of this podcast.]


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  1. 1. promytius 08:54 AM 4/30/11

    no "real" brain eh, what are they using, the Cloud? No brain? What a fake brain, a virtual one? They then must problem solve by what, chance? How can you possibly have a "clever strategy" without a brain? What's with all the anthropomorphism anyway? I think somewhere box jellyfish are looking up at someone's laptop, reading this article and enjoying it - not with their brains of course, and not enjoying in the sense of human enjoyment, more jelly-like enjoyment.

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  2. 2. candide 09:25 AM 4/30/11

    The article also says that these jellyfish "actively hunt prey" - sort of describes the function of some type of brain, right? So it's not a bi-lateral, mammalian type brain, it may be a very different, primitive, radially symmetric neural-net "brain."

    "What's with all the anthropomorphism anyway?"

    I agree, it's a bit over the top. One of my complaints with Scientists in general, and SciAm in particular, is the constant perceived need to dumb-down (or popularize) the information being presented.

    Not only does doing that lose some of the veracity and effectiveness it subtly says "Hey, we're smarter than you and know that you couldn't understand this."

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  3. 3. Mike Barry 06:51 PM 4/30/11

    Huh?

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