(Post by Brianna Valentine)
Odontodactylus scyllarus, better known as the peacock mantis shrimp may be a fascinating, colorful crustacean to look at, However it is not one you would want to invite into your salt-water pool or aquarium. This destructive little shrimp will punch to death anything in its path without mercy. The mantis shrimps’ aggressive way of dealing with its prey has made it quite famous in the scientific and marine community. The mechanisms behind the punching action done by these creatures raises many questions, however it may be helpful to first learn some background information on the mantis shrimp. The peacock mantis shrimp belongs to the phylum arthropoda, subphylum crustacea and order stomatopoda. The mantis shrimp is commonly found in coral reefs due to its preference of shallow, clear water (Kleinlogel and Marshall, 2009). This crustacean feeds on anything from fish, snails, crabs and mollusks (Kleinlogel and Marshall, 2009) despite its small size.
A peacock mantis shrimp showcasing its bright colors. Photo by Charlene Mcbride. Used under creative commons generic license.
The enlarged appendages located on the anterior of the mantis shrimp, also known as the thoracic raptorial appendages (Patek and Caldwell, 2005), used to kill prey, have made this stomatopod famous. The massive strike of the mantis shrimp appendages are able to kill fish and break through hard shells such as those on crabs and mollusks (Patek and Caldwell, 2005). These powerful and deadly strikes happen in less than a second (often a few milliseconds) and have deemed the mantis shrimp to possibly be the “fastest appendicular striker in the animal kingdom”(Patek et al. 2004). The force from these strikes of the shrimp are thousands of times their body weight (Patek and Caldwell, 2005) and is another reason the mechanisms of these appendages have become of such interest.
The breaking of shells is more often done by a force applied over a long period of time rather than a very short striking force such as that done by the mantis shrimp. The appendages work like a spring which stores and releases energy with latches that prevent movement until maximum muscle contraction is achievable (Patek et al. 2004). The ability of the mantis shrimp to kill prey in such a manor is broken down into two forces (Patek and Caldwell, 2005). The first force is the actual strike of the appendages and contact to the shell or prey. The second is the cavitation, or the formation and collapsing of bubbles, which occurs from the abrupt motion of the shrimp striking the prey. The force from the appendages of the mantis shrimp can be anywhere from 400N to 1500N (Patek and Caldwell, 2005). The forces from cavitation have been recorded up to 504N (Patek and Caldwell, 2005). These two forces tend to occur within 390-480μs of each other (Patek and Caldwell, 2005) and have serious consequences for anything in their path.
Eyes and raptorial appendages of mantis shrimp. Photo by Elias Levy. Used under creative commons generic license.
The mantis shrimp also uses its raptorial appendages in making burrows and defense as well as fighting other O.scyllarus species (Patek and Caldwell, 2005). These magnificent stomatopods are not only intriguing in appearance but might be one of the most entertaining to observe. The functioning and mechanisms behind the death punch of the mantis shrimp prove to be another mind-blowing feature of the animal kingdom. The peacock mantis shrimp may just be one of the toughest little creatures of the sea.
References
Charlene Mcbride. Photo. Accessed online March 12, 2016. https://www.flickr.com/photos/ursonate/4481222867/in/photostream/.
Elias Levy. Photo. Accessed online March 12, 2016. https://www.flickr.com/photos/elevy/14465973722.
Kleinlogel S, Marshall JN. 2009. Ultraviolet polarization sensitivity in the stomatopod crustacean Odontodactylus scyllarus. Journal of Comparative Physiology A. Accessed online March 12, 2016 at http://link.springer.com/article/10.1007/s00359-009-0491-y.
Patek SN, Caldwell RL. 2005. Extreme impact and cavitation forces of a biological hammer: Strike forces of the peacock mantis shrimp Odontodactylus scyllarus. Journal of Experimental Biology. Accessed online March 11, 2016 at http://jeb.biologists.org/content/jexbio/208/19/3655.full.pdf.
Patek SN, Korff WL, Caldwell RL. 2004. Biomechanics: Deadly strike mechanisms of a mantis shrimp. Nature. Accessed online March 11, 2016 at http://www.nature.com/nature/journal/v428/n6985/full/428819a.html.
