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The eyes of Anomalocaris

Look with your puny camera eyes! Some new specimens of Anomalocaris, the spectacular Cambrian predator, have been discovered in South Australia. These fossils exhibit well-preserved eyes, allowing us to see that the bulbous stalked balls on their heads were actually fairly typical compound eyes, like those of modern insects.


Anomalocaris eyes from the Emu Bay Shale. a–d, Eye pair, SAM P45920a, level 10.4 m. a, b, Overview and camera lucida drawing. Scale bars, 5 mm. Grey fill in b represents visual surface, the proximal part in the upper eye extrapolated from the lower eye. c, Detail of ommatidial lenses located by horizontal white box in a. Scale bar, 1 mm. d, More complete eye, showing transition between visual surface and eye stalk (white arrows). Scale bar, 2 mm. e, Detail of ommatidial lenses in counterpart SAM P45920b. Scale bar, 0.3 mm. es, eye stalk; I.c., Isoxys communis; us, undetermined structure; vs, visual surface. Tilted white box in a represents area analysed using SEM-EDS.

The cool part of this discovery: the investigators were able to count the density of lenses and estimate how many were present in the intact eye. The number is 16,000 ommatidia in each eye, which is more than a little impressive: to put it in context, Drosophila has about 800. The emphasis on high-resolution vision suggests that Anomalocaris was diurnal predator in shallow water.

Oh, and just in case you’re one of those strange beings who isn’t instantly familiar with what the anomalocarids looked like, here’s a video to remind you.


Paterson JR, García-Bellido DC, Lee MS, Brock GA, Jago JB, Edgecombe GD (2011) Acute vision in the giant Cambrian predator Anomalocaris and the origin of compound eyes. Nature 480(7376):237-40.

(Also on Sb)

Comments

  1. says

    Because if it can see you, it can taste you.

    Oh, and it couldn’t have evolved (hosts of creationists have said so!), for the usual reasons, especially the lack of evolved intelligence in IDiots/creationists.

    Glen Davidson

  2. kieran says

    Time till this is misquoted by a creationist at ICR? I’ve got thursday the 22nd for a tenner. Any takers?

  3. Brownian says

    The number is 16,000 ommatidia in each eye, which is more than a little impressive

    Especially to a Cambrian optometrist.

    “Now, with the 2,343rd ommatidium: is ‘A’ better, or is ‘B’? Again, ‘A’…and ‘B’.”

  4. rukymoss says

    It looks as if the dorsal and ventral views are oppositely labelled–or am I just looking at it funny? Either way, it’s wondrous that anyone could look at the fossils and be able to pick out the amazing details.

  5. Hercules Grytpype-Thynne says

    It looks as if the dorsal and ventral views are oppositely labelled–or am I just looking at it funny? Either way, it’s wondrous that anyone could look at the fossils and be able to pick out the amazing details.

    Yeah, the labels seem backwards unless for some reason they think the thing swam upside-down.

    Either way, though, an awe-inspiring sight. It’s more than a shame that Noah wasn’t able to save any of these wondrous creatures from the Flood. </snark>

  6. says

    Brownian gets +1 intertubes.
    ++++++++++++
    A Anomalocaris goes to the optometrist. The doctor finishes the exam and says “Your ommatidia look OK, but you have to stop masturbating.”

    “Why Doc, am I going blind?”

    “No, you were disturbing the other patients!”

    [http://instantrimshot.com/]

  7. David Marjanović says

    Have we ever figured out how the mouth parts worked? I could never grok that from my previous exposures to them.

    Probably they came out like puckered lips and approached each other during retraction.

    Yeah, the labels seem backwards unless for some reason they think the thing swam upside-down.

    They don’t. The mouth is ventral as it should be, and they label that side “dorsal”.

    Brownian gets +1 intertubes.

    Alas, one ommatidium doesn’t have enough resolution for such things.

  8. petrander says

    You mean 2 * 16 Megapixel? Pfft! We’ll have that resolution soon enough on our smartphones too! :-P

  9. Hercules Grytpype-Thynne says

    Yeah, the labels seem backwards unless for some reason they think the thing swam upside-down.

    They don’t. The mouth is ventral as it should be, and they label that side “dorsal”.

    Okay, fine. I should have written “swam upside-down and had a mouth on the top of its head.”

  10. 'Tis Himself, OM. says

    Our Cephalopodian Overload neglected to mention that Anomalocaris could grow to two meters long.

  11. Luc says

    Evolution disproved by fossils! That’s not what you should expect from an old bug according to Darwin.

    Unless you can show me a perfect series that begins with a bug with 1 ommatidium, then another bug with 2 ommatidia, then a bug with 3 and so on, exquisitely placed in a linear continuum up the strata, then evolution is a lie.

    (Not)

  12. SteveV says

    myeck waters
    Have we ever figured out how the mouth parts worked? I could never grok that from my previous exposures to them.

    Do you have scars?

  13. Ichthyic says

    Okay, fine. I should have written “swam upside-down and had a mouth on the top of its head.”

    technically, there is nothing to suggest they actually DIDN’T swim upside down to search for prey on the benthos, then right themselves to go and grab it.

    though, I think the eyes large enough and close enough to the lateral parts of the head to suggest they didn’t need to invert to see the bottom, even when swimming upright.

    that’s about all that can be said, really.

  14. procyon says

    This seems like a highly evolved arthropod eye so early in metazoan evolution. I wonder how trilobite and other arthropod eyes of the same time period compare.

  15. Active Margin says

    How disappointing that they aren’t still around. Speaking of, what descendants (if any) did Anomalocaris leave us with?

  16. shouldbeworking says

    I have one of them on a coffee cup from the Royal Tyrrell Museum. One of my fave science themed cups.

  17. says

    Speaking of, what descendants (if any) did Anomalocaris leave us with?

    Generally, a fossil species is generally assumed to leave no descendents. The odds are quite against.

    Worse, many paleontologists and taxonomists think that Anomalocaris belonged to an entire phylum that went extinct, as many Cambrian phyla did (yes, the “Cambrian explosion” was a miracle, God just neglected to keep a number of phyla from going extinct soon thereafter).

    To be sure, taxonomy isn’t an exact science when we’re dealing with extinct organisms.

    Glen Davidson

  18. frankb says

    Being the top predator back then is not saying very much. If an adult human caught one of those in the shallows, it would be in for a stomping.

  19. CompulsoryAccount7746 says

    I seem to recall a decent-looking anomalocaris animation from PBS’s “Evolution” series where a trilobite’s bite mark was matched to that bagel mouth. Alas, I couldn’t find it scrubbing around on youtube/google video.

  20. hypocee says

    And coincidentally I just yesterday read A Colder War, in which Anomalocaris eventually turns out to be evidence of previous contact with extraterrestrial ‘weakly godlike agencies’ including the K-Thulu entity.

  21. Lofty says

    Would it be able to claim warranty from its creator if it had deal pixels? Eyes being perfect an’ all that.

  22. michaeldavies says

    @NelC – There are normally fixed crystalline lenses on each ommatidium, and according to this nice introduction they are probably set up for best discrimination in near field, so there will be less detail for objects further away.

  23. David Marjanović says

    This seems like a highly evolved arthropod eye so early in metazoan evolution.

    Metazoa is probably twice that old. Anomalocaris lies just outside Arthropoda-in-the-strictest-sense.

    I wonder how trilobite and other arthropod eyes of the same time period compare.

    Identical, only smaller and with fewer ommatidia.

    Being the top predator back then is not saying very much. If an adult human caught one of those in the shallows, it would be in for a stomping.

    What a pity that someone didn’t read comment 15.

  24. gnuatheist says

    If you’d like more of this stuff, there’s a new book out titled, “EVOLUTION’S WITNESS, How Eyes Evolved”. It’s written by Dr. Ivan Schwab, an ophthalmologist from UC Davis, and published by the Oxford University Press.

    I’m an ophthalmologist myself, and I love the “What good is half an eye?” argument from evolution deniers. The book is well researched and illustrated and it is fairly technical. It was definitely written for folks with medical or scientific backgrounds, but it is very readable. PZ, I’d love to know what you think of it.

    In case you’re wondering, I have no financial or other interest in this book. I saw Dr. Schwab speak at a recent ophthalmology conference and he was very engaging. He also has a blog called “Evolution’s Witness” that I plan to explore further.