Trilobite Eye Dazzles Government Engineers

This extinct marine animal had binocular eyes with
such amazing properties they want to imitate it

We justly admire the “eagle eyes” of birds of prey alive today, but exceptional eyes go far back to the first multicellular animals.

Trilobites (according to the evolutionary timeline) appeared in the geological blink of an eye in the Cambrian Explosion that began 540 million years ago. At their first appearance, they already had jointed appendages, internal organs for digestion and reproduction, a nervous system, and compound eyes. Numerous species of trilobites, all maintaining the overall body plan of arthropods, are known from the fossil record. They thrived around the globe well into Ordovician strata, then suddenly disappeared (although extant horseshoe crabs may be related).

The remarkable diversity of eyes among trilobites challenges evolutionary theory—not just because eyes popped into existence so suddenly (see Popeye Theory of Evolution, xx), but because each type is so different without transitional forms. One particular species had binocular vision with exceptional optics, so unusual that engineers at the National Institute of Standards and Technology (NIST) took a closer look. What they saw challenged them to see if they could achieve similar performance.

Inspired by Prehistoric Creatures, NIST Researchers Make Record-Setting Lenses (NIST, 19 April 2022).

Five hundred million years ago, the oceans teemed with trillions of trilobites — creatures that were distant cousins of horseshoe crabs. All trilobites had a wide range of vision, thanks to compound eyes — single eyes composed of tens to thousands of tiny independent units, each with their own cornea, lens and light-sensitive cells. But one group, Dalmanitina socialis, was exceptionally farsighted. Their bifocal eyes, each mounted on stalks and composed of two lenses that bent light at different angles, enabled these sea creatures to simultaneously view prey floating nearby as well as distant enemies approaching from more than a kilometer away.

Inspired by the compound eyes of a species of trilobite, researchers at NIST developed a metalens that can simultaneously image objects both near and far. This illustration shows the structure of the lens of an extinct trilobite.
Credit: NIST

It would be very useful to make cameras with lenses that could focus simultaneously on near and far objects, not only for consumers with cameras but also for the military. Most lenses are limited in their reach of focus, called depth of field. Noting how well this species of trilobite accomplished the feat, NIST engineers set out to make their own version. The result: “metalenses” that could focus on objects as close as 3 cm and as far as 1.3 km – a new record.

Such lightweight, large-depth-of-field cameras, which integrate photonic technology at the nanometer scale with software-driven photography, promise to revolutionize future high-resolution imaging systems. In particular, the cameras would greatly boost the capacity to produce highly detailed images of cityscapes, groups of organisms that occupy a large field of view and other photographic applications in which both near and far objects must be brought into sharp focus.

At first, their device was good at focusing at both near and far extremes, but intermediate objects were blurry. Using another bio-inspired trick, they succeeded in focus for the entire range:

Without further processing, however, that would leave objects at intermediate distances (several meters from the camera) unfocused. Agrawal and his colleagues used a neural network — a computer algorithm that mimics the human nervous system — to teach software to recognize and correct for defects such as blurriness and color aberration in the objects that resided midway between the near and far focus of the metalens.

For those interested in the details of the optics, Amit Agrawal’s team at NIST published their results in the open-access journal Nature Communications at the following link:

Fan et al., Trilobite-inspired neural nanophotonic light-field camera with extreme depth-of-field. Nature Communications volume 13, Article number: 2130. 19 April 2022.

In the paper, the authors note that “To the best of our knowledge, this type of compound-eye visual system is unique to Dalmanitina socialis, and is in contrast to the single focal vision system present in all-known living arthropods that exist today.”

Trilobite (animation in Illustra Media’s documentary, Darwin’s Dilemma)

No ancestors for the first trilobite; no intermediates between this species and other trilobites; what does that imply? Trilobites were created fully formed, not by a gradual Darwinian process. Not surprisingly, the press release and technical paper say nothing about evolution.

Watch trilobites come to life in Illustra Media’s film Darwin’s Dilemma. The entertaining and informative production explains why the Cambrian Explosion is such an insurmountable hurdle for evolution.