Pistol packing … Shrimp?!

Watch out for this little guy!


illustrated by Caleb SalisburyPistol shrimp

Do you like shrimp for dinner? Well don’t mess with this pistol packing hombre! Despite being a diminutive 1–2 inches (3–5 cm) long, the pistol shrimp normally has one regular claw but also has an oversized claw which operates as an acoustic weapon capable of producing ‘gunshots’ reaching over 200 decibels (much louder than a jet engine!).

Unwary victims approaching within an inch or so (~4 cm) of this oceanic ‘bush-whacker’ may find themselves staring down the barrel of a gun that is literally cocked and triggered in a fashion reminiscent of a Wild West six-shooter.

Reach for the sky!

The sound the shrimp makes is not produced by its claws snapping together but by a bubble formed by a fast water jet (travelling at speeds of up to 60 miles/100 kilometres an hour) squeezed out from a socket in the claw when it snaps shut (this generates a low-pressure bubble).

The violent implosion of this cavitation bubble produces the sound blast, the pressure of which is strong enough to kill small fish. (This is similar to the pistol shrimp’s larger cousin, the 4–6 inch-long (6–10 cm) mantis shrimp’s use of cavitation to boost its ‘super powered’ punches). Researchers using high-speed cameras and sound equipment say this whole process occurs within 300 microseconds from when the shrimp ‘pulls the trigger’. The implosion also briefly generates a temperature as high as the sun’s surface.

The shallow ocean gang

Not only are these shrimp armed and dangerous, they are also a rowdy bunch (“ … the shrimps’ snapping is the dominant source of background noise in the shallow ocean”1). They can easily compete with 40 ton heavyweights like whales in terms of ability to create noise. In colonies they can interfere with submarine sonar; “When colonies of the shrimp snap their claws, the cacophony is so intense submarines can take advantage of it to hide from sonar.”2 (This problem was first discovered in WW II because these creatures made it hard to detect hostile submarines!) Not only are the ‘gunshots’ used to attack, they are apparently used for communication as well.

Don’t mess with this pistol packing shrimp!

Cover me boys!

Several species of goby fish don’t fear this creature. The shrimp even rests its antennae on the goby’s tail and body. Both sides benefit from this symbiotic relationship. The shrimp can’t see well, so any sudden movement by the goby signals the shrimp that it’s time to hide in its burrow. In return, the goby is allowed to share this burrow for a safe home.3 Symbiosis can be yet another conundrum for evolution.

Now on the other hand …

Unlike their gun-toting cowboy counterparts, pistol shrimps are notoriously hard to disarm. Another clever trick up their sleeve is their ability to literally ‘switch hands’. Laboratory research has shown that if something chops off the shrimps ‘pistol’ hand, the missing limb will regenerate into a regular smaller claw and the original normal appendage will grow into a new snapping claw (severing the nerve of the snapping claw induces the conversion of the smaller limb into a second snapping claw). Some shrimp even have two pistol claws.4

Design demands a designer?

Many people, astounded at the obvious design in such a creature, might ask, “How could features such as the building of a sonic gun (along with the biochemical and neural pathways that would need to be integrated into the creature’s central nervous system) just happen by mutations and natural selection?” But an informed evolutionist might easily counter this appeal to design in this way:

“All shrimp have claws already with neural pathways for control of closing of the claw to catch prey (and quite quickly). Some might even discover that suddenly closing their claw to jet water at small prey at close quarters, but just out of reach, disorients them sufficiently for the shrimp to catch them. This process could have been refined by slight changes to the claw over a period of time (via mutations), developing more and more effective jets, culminating in ones with a sonic boom, as in this species. The sonic boom is just the end result of the modification of existing structures.”

(Please note that the purpose of the following critique is not to set up a straw man argument against evolution. The argument used [above] is hypothetical, but typical of how evolutionists have argued against ‘design’ in the past. This exercise is to show how these particular points could be argued against.)

Call their bluff

This might stump some, or convince them that evolutionary concepts are credible. But close examination reveals holes in such an argument. First of all, the use of terminology like “ … some might even … ”, “ … could have been … ” (commonly seen in evolutionary literature) highlights the fact that these kinds of arguments are imaginings, not observed facts or even extrapolations based on fossil evidence of transitional forms, etc.

Neo-Darwinian evolution says that tiny changes in living things that are useful to the organism (providing some kind of survival benefit) are retained. This means a bunch of smaller changes can result in big changes (like a leg into a claw or a claw into a ‘sonic gun’). However, evolutionist Richard Dawkins admits:

“There cannot have been intermediate stages which were not beneficial. There’s no room in natural selection for the sort of … foresight argument, that says: ‘Well we’ve got to let it persist for the next million years and it’ll start becoming useful’ … That doesn’t work. There’s got to be a selection pressure all the way.”5

The pistol shrimp’s claw is an extremely specialized construct that needs precision design in order to function. Of the millions of random mutations that might occur that would change the shape of a claw (a bump, indentation or protrusion of some sort?) there would be precious few that would have been ‘on the way’ to becoming a ‘sonic gun’ variant. Granting that evolutionists admit that beneficial mutations are rare, the point is; “What survival benefit would those small shape changes have conferred to the shrimp on the way to becoming a sonic claw?”

A similar comparison would be scales turning into feathers. As the scale changed slightly, becoming something like a small bump or pimple, one has to wonder what advantage that might give a lizard (on its way to becoming a bird). Dawkins actually discussed this in an interview with TV show host Jonathan Miller:

JM: “What was it about that early novelty, before it culminated in something as useful as a feather? Where could natural selection get its purchase upon something which was no more than a pimple?”

RD: “ … there’s got to be a series of advantages all the way in the feather. If you can’t think of one, then that’s your problem, not natural selection’s problem. Natural selection, well, I suppose that is a sort of matter of faith on my part since the theory is so coherent and so, and so powerful.”6

So Dawkins’ belief is based on faith, not fact, just like the hypothetical argument above.

Pistol shrimp and goby in symbiotic relationship

Tall Tales

One also has to wonder why shooting bubbles (at lesser speeds than those that which can cause implosive cavitation bubbles) would ‘disorient’ a fish long enough to allow a shrimp to catch it. Surely a sudden jet of bubbles of any velocity would most likely frighten prey, thus prompt them to flee away from them, not closer. The only reason a pistol shrimp can eat a meal he’s shot with his gun is because it is stunned or dead!

Also, as the claw supposedly begins changing from an efficient grabbing tool into a ‘gun’, its efficiency as a grabbing tool is surely going to be diminished. Natural selection would work against such a change to eliminate it, unless the efficiency of the claw as a gun were sufficient to make up for this. Creating a few bubbles would hardly suffice to enhance survival enough to make up for the loss of grabbing efficiency.

There is no present-day example (or in the fossil record) known of a shrimp or crab with some kind of intermediate claw that disorients fish by shooting bubbles at lesser speeds. There would be a threshold for the speed of snapping shut and the volume of water displaced for the mechanism to make any difference at all. Natural selection could not work on further improving this mechanism until this threshold was reached. As Dawkins admitted, natural selection could not foresee an amazing mechanism that would be achieved in the future.

According to Dawkins, “Biology is the study of complicated things that give the appearance of having been designed … ”7 (emphasis mine). The ‘design’ argument has been a powerful instrument in the creationist’s apologetic ‘tool kit’ for years and evolutionists have often tried to explain away examples of design with ‘just so’ stories rather than observable evidence. But just because evolutionists say that there is a way that evolutionary mechanisms could have produced such and such doesn’t mean that it did or that such an explanation is credible.

The evolutionists’ series of diagrams supposedly showing how an eye could evolve is a case in point. Beneath the simplistic line-diagram scenario lies nightmarish biochemical complexity. Even the humble ferment fly (Drosophila) has over 500 genes involved in eye development.8 Vertebrates have many thousands of genes. Even one of these genes is beyond mutations and natural selection to ‘create’. Even a light-sensitive spot—the evolutionists’ first stage—involves enzyme cascades that the evolutionary story sidesteps to make the story seem plausible.

As Romans 1:20 says, the evidence that the creator God of the Bible exists is clearly seen in His creation, from the largest of whales to the tiny shrimp!

Published: 17 April 2012


  1. Snapping shrimp drown out sonar with bubble-popping trick, described in Science, ScienceDaily.com, 22 September 2000. Return to text.
  2. Ref. 1. Return to text.
  3. Bizzare Fun Facts About Pistol Shrimps ,February 23, 2013 by AnirudhReturn to text.
  4. Pearce, J. and Govind, C.K., Spontaneous generation of bilateral symmetry in the paired claws and closer muscles of adult snapping shrimps, Development 100:57–63, 1987. Return to text.
  5. Jonathan Miller’s “Brief History of Disbelief” BBC Two, Monday 14th November, 7–8 pm, originally broadcast October 2004, BBC4. Return to text.
  6. Ref. 5. Return to text.
  7. Dawkins, R., The Blind Watchmaker, W.W. Norton & Company, New York, USA, p. 1, 1986. See also the articles under <creation.com/dawk>. Return to text.
  8. Bergman, J., Did eyes evolve by Darwinian mechanisms? Journal of Creation 22(2):67–74, 2008. Return to text.