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 FtB)