Creationists love mantis shrimp

The following article was originally posted on Arthropoda on November 24th, 2009. It was only the 5th blog post I ever made, but it is still one of my favorites.

My graduate adviser and some of his collaborators recently published a paper in Nature Photonics, about the efficiency of the natural quarter-wave retarder used in the mantis shrimp’s circularly polarized light detection system. The paper got a lot of play in popular press (because mantis shrimp are awesome), including a write-up by the unintentionally hilarious Institute of Creation Research (ICR). This group has been trying for years to gain Masters of Science Education accreditation in California, and now Texas (this attempt at undermining higher education has astonishingly been denied so far).

Too be fair, their article actually starts off better than most of the popular science writing about these animals. However, after the fifth paragraph it takes a nose-dive into a mire of fairly typical creationist misconceptions and misdirections. The downward spiral begins with a heaping helping of “living-fossil” nonsense.

“The mantis shrimp is also one of many examples of “living fossils”―creatures that have not changed over supposedly vast evolutionary time spans. Some modern mantis shrimps are exactly the same as their ancestors that were fossilized in Devonian strata, which have been assigned an astounding age of 400 million years. The odds of this creature remaining unchanged for that length of time are fantastically remote.”

facepalm-captain-picard

First off, there is no such thing as a living-fossil. This unhelpful term is used by biologists who should know better, repeated incessantly by the popular media, and trumpeted by creationists who use it to shoot holes in good science. Everything alive today has been evolving for exactly as long as everything else. The two species of modern coelacanth, for instance, are not the same as the once successful Devonian lobefin group from which they are derived. They may retain superficial ancient characteristics, but they are completely distinct animals. Likewise, no biologist claims that mantis shrimp have remained unchanged since the Devonian. Mantis shrimp diverged from other crustaceans around the Devonian. Here is a comparison between a fossil and modern mantis shrimp:

A reconstruction sketch of a fossil proto-mantis shrimp (left) versus a modern Squilloid mantis shrimp. The colored arrows demonstrate obvious areas of morphological divergence. Adapted from Schram, 2007 and Ahyong, 2001.

Sure they share some superficial similarities (similarities also shared with thousands of other malacostracan crustaceans, arthropods, bilaterians, metazoans, and so on at a diminishing rate). However, the 500 diverse species of modern mantis shrimp are different animals from their ancient ancestors; with widely variant morphologies and distinct ecologies.

Take, for example, the raptorial appendages (red arrow). The raptorial appendages in modern mantis shrimp are massively enlarged maxillipeds (mouth-parts). These appendages are now highly specialized and used specifically for predation, defense, and competition. You can see that the fossil proto-mantis shrimp does not have an enlarged set of maxillipeds. It took hundreds of millions of years for them to evolve to their modern glory. This evolutionary modification of the first maxillipeds is obvious in the fossil record, and has transformed the ecology of today’s mantis shrimp; making them one of the most voracious and violent predators in the ocean.

The ICR continues,

“And the odds of nature having constructed the world’s most complicated eyes so soon after the “Cambrian Explosion” of life, only to have left them perfectly alone ever since, seems counter-evolutionary.”

The eyes, like the raptorial appendages, obviously did not reach their full complexity when the mantis shrimp diverged in the Devonian. They also took hundreds of millions of years of evolution to develop from their proto-typical form into their elaborate modern design. There is nothing “counter-evolutionary” about the mantis shrimp eye.

“This research had little to say about the origin of the mantis shrimp eye, but it is clear that such high design demands a high designer.”

double-facepalm
Argument from incredulity? Check!

Evolution builds complexity, the currently unknown is not unknowable, and just because we haven’t figured a particular detail out yet doesn’t mean we are going throw our arms in the air and give up. “Vision is complicated and science is hard, therefore God did it,” is a pitiful capitulation.

“While the source of mantis shrimps’ rarefied level of vision is unclear to evolutionists, other researchers, who are not convinced that nature is the only explanatory option for ultimate origins, suspect that the exquisite level of specificity, elegance, and effectiveness in the mantis shrimp vision system testifies to the unsurpassed level of the Creator’s genius.”

The source of stomatopod vision is not unclear to evolutionists. It is obviously the modified product of a suite of evolutionarily conserved visual pigments and optical components. These components are closely related to those in other crustaceans, slightly less related in other arthropods, and present (in some form) in all animals.

Also, I would like to know who these “other researchers” are. I am fairly well immersed in the mantis shrimp literature; it is not a huge research community. Nowhere have I heard a researcher present evidence or submit speculation that mantis shrimp are anything but the product of evolutionary processes. These “other researchers” are not studying the mantis shrimp visual system. They cherry-pick research from real scientists, and throw a creationist spin on it. Actual researchers do not doubt the evolutionary ancestry of the mantis shrimp visual system.

Creationists love mantis shrimp for one of the same reasons that I love them: because they are complicated. Creationists see this complexity, reported to them by actual researchers, and having done no work of their own, declare victory. Scientists also love mantis shrimp for their complexity. They offer unique and exciting opportunities for further research. Research in genetics, evolution, biomechanics, visual ecology, and neurobiology.

Tomorrow, countless scientists will go into their offices, labs, observatories, and field stations. They will work to better understand our world, and communicate that understanding with others. Scientists are driven by the ecstasy that comes with discovery, and they need not doubt that, “somewhere, something incredible is waiting to be known.” –Carl Sagan

References:

  • Roberts N, Chiou T, Marshall N, & Cronin T (2009) A biological quarter-wave retarder with excellent achromaticity in the visible wavelength region Nature Photonics, 3 (11), 641-644 DOI: 10.1038/nphoton.2009.189
  • Ahyong ST (2001) Revision of the Australian stomatopod Crustacea. Records of the Australian
    Museum
    Supplement 26: 1–326.
  • Schram FR (2007) Paleozoic proto-mantis shrimp revisited. Journal of Paleontology 81; 895-916.

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About Mike Bok

Grad student studying the vision of mantis shrimp.
This entry was posted in Creationism and tagged , , . Bookmark the permalink.

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