Mantis shrimp dismantles clam

July 28, 2023 • 2:00 pm

It’s Friday afternoon, the ducks are fed and watered for the weekend (it’s hot today but will cool down) and I’m soon off to hear about the fate of Botany Pond. This all means that it’s time for ani animal video.

How does it do this?  See the next video, which shows that the shrimp actually packs a double punch, with the second involving boiling water.

The explanation from Wikipedia:

Mantis shrimp are commonly separated into many (most fall into spears and smashers but there are some outliers)[9] distinct groups determined by the type of claws they possess:

  • Smashers possess a much more developed club and a more rudimentary spear (which is nevertheless quite sharp and still used in fights between their own kind); the club is used to bludgeon and smash their meals apart. The inner aspect of the terminal portion of the appendage can also possess a sharp edge, used to cut prey while the mantis shrimp swims.
  • Spearers are armed with spiny appendages – the spines having barbed tips – used to stab and snag prey.

Both types strike by rapidly unfolding and swinging their raptorial claws at the prey, and can inflict serious damage on victims significantly greater in size than themselves. In smashers, these two weapons are employed with blinding quickness, with an acceleration of 10,400 g (102,000 m/s2 or 335,000 ft/s2) and speeds of 23 m/s (83 km/h; 51 mph) from a standing start.[10] Because they strike so rapidly, they generate vapor-filled bubbles in the water between the appendage and the striking surface—known as cavitation bubbles.[10] The collapse of these cavitation bubbles produces measurable forces on their prey in addition to the instantaneous forces of 1,500 newtons that are caused by the impact of the appendage against the striking surface, which means that the prey is hit twice by a single strike; first by the claw and then by the collapsing cavitation bubbles that immediately follow.[11] Even if the initial strike misses the prey, the resulting shock wave can be enough to stun or kill.

Smashers use this ability to attack crabssnails, rock oysters, and other molluscs, their blunt clubs enabling them to crack the shells of their prey into pieces. Spearers, however, prefer the meat of softer animals, such as fish, which their barbed claws can more easily slice and snag.

6 thoughts on “Mantis shrimp dismantles clam

  1. Thanks for the great post on fantastic animals.

    Shelia Patek and her students have shown that the velocity of the club (or spear) is much faster than the velocity of the muscle contraction in the limb. That seems impossible! The solution is clever: instead of using muscles to fling the club forward, the stomatopod uses slow muscles to compress a spring in the exoskeleton; the release of the spring generates much more force and faster acceleration of the club than could be generated by muscles acting directly on the joints & levers of the limb. It’s great work.

  2. Yikes!.There are certainly enough freaky species on this planet without worrying about aliens visiting in their UFOs.

  3. Dive guides always told us not to get too close when trying to take pix–they could break your lens or lens housing. Think I have a few old images somewhere on a hard drive.

  4. Mantis shrimp make me feel guilty, especially since they’re so cool and specialized (their eyes for one thing, as mentioned above). Plus their just so damn beautiful, darting around with their brilliant colors and intensity. But I used to keep coral reef aquariums, and an indispensable part of the set-up are “live rock.” It’s the basis for any reef aquarium, and when you buy the rocks, you never know what lurks within (part of the fun, actually). Most of the time, you’ll discover very cool stowaways, but sometimes, a mantis shrimp, which is also cool, but not good. In an aquarium, they’ll decimate your critters. I’ve had to kill two (no easy task capturing them) during my reef-hobby years, thus my guilty feeling (quit the hobby in 2007 because of environmental concerns). Though I had the idea of just keeping a mantis because they were so enthralling, but after a little research, read horror stories of folks who did just that but the mantis (by accident) would often break the aquarium glass while hunting. NHO! Those buggers are an evolutionary marvel; and keep them in the ocean where they belong.

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