The mantis shrimp is probably one of the most outlandish looking animals on the face of this planet. Looking like an odd mix between a praying mantis and a large terrestrial bug, these predacious creatures feature some of the most highly evolved physical attributes of any invertebrate known to man. These marine crustaceans belong to the order stomatopoda, comprised of around 400 recognised species that are either identified as smashers or spearers according to the shape of their main forelegs and the use of them in obtaining prey.
Figure 2 shows the one of the massively muscled main arms of a smashing mantis shrimp. Smashers like the Peacock Mantis Shrimp in Figure 1 drive their club-like elbows into their prey at blinding speeds- up to 2300cm/s in a strike lasting 0.0027ms, the fastest strike of any creature on earth (Patek and Caldwell, 2004). They have earned the nickname ‘thumb splitters’ by divers who have inadvertently gotten to close to these crustaceans, whose blows easily render skin and flesh to the bone.
In a bid to understand this process, researchers at the University of California, Berkeley utilised high-speed video cameras with frame rates of 100000 frames/s. Here they discovered the truly devastating nature of smashing mantis shrimp strikes when they observed the phenomena known as cavitation and sonoluminescence occurring during each attack (Patek and Caldwell, 2005).
Video 1. High-speed footage of club-footed stomatopod strike
The footage above shows the process of one species of smashing stomatopod, odontodactylus scyllarus, bullying a snail. In layman terms, besides the nasty impact, the strike agitates the water near the point of impact so much that a flash of light, extreme heat and a damaging sonic wave are produced. From the snail’s perspective it is akin to getting hit by a speeding train laden with volatile explosives, that can hit you again and again. And again.
Video 2. Peacock Mantis Shrimp (odontodactylus scyllarus) feeding
As observed in the clip above, mantis shrimp attack with astounding ferocity. Bear in mind that sound of the stomatopod’s strikes are being recorded from outside of the tank, implying some serious impact. Also observed from the video is the surprising agility of all mantis shrimp. Unlike most slow moving crustaceans, stomatopods are aggressive, highly mobile creatures that actively seek out their prey. They routinely leave the seabed and are swift swimmers that easily overpower fish that swim above the seabed.
Stomatopods are also known to have the most developed compound eyes of the animal kingdom. They have incredibly sophisticated depth perception and can detect both circular and linear polarised light, a feature as yet undiscovered in any other animal (Kleinlogel and White, 2008). This enables them to maintain perfect vision in an environment that is subject to constant ambient light changes. The presence of transparent or camouflaged prey and predators prove no challenge or threat to a creature with such well-developed eyes (White, 2008)
The aggressive behaviour of this intelligent predator and the highly specific physical attributes they display seem to be the result of an evolutionary path taken to ensure survival in an ultimately competitive environment (Caldwell and Hugh, 1975). Club-footed mantis shrimp like the Peacock Mantis Shrimp (odontodactylus scyllarus) shown in the videos above live amongst rocks and coral formations in tropical waters that are teeming with life. Competition within semi-permanent rock burrows is rife, and encounters with various other vertebrates and invertebrates in this crowded habitat have caused an evolutionary ‘arms race’ amongst the reef’s inhabitants (Caldwell and Hugh,1975).
Their highly developed mobility, forelegs and compound eyes are the reasons why stomatopods like odontodactylus scyllarus flourish as predators.
Figure 1. “Mantis Shrimp” by buzzthediver, (20th Feb 2010) Accessed 1sp April 2010, under Creative Commons License. URL: http://www.flickr.com/photos/buzzthediver/4372922934/
Figure 2. “Smasherrap” by Dr. Roy Caldwell, (July 2001) Accessed 1st April 2010, University of California Museum of Paleontology. URL:http://www.ucmp.berkeley.edu/aquarius/raps.html
Figure 3. “Mantis Shrimp” by Enje, (18th May 2009) Accessed 31st March 2010, under Creative Commons License. URL: http://www.flickr.com/photos/ejbali/3540160955/
Video 1. “High Speed Footage of Mantis Shrimp Strike” by Sheila Patek (16th Sept 2005) (Taken on an Ultima APX high speed camera with Multi-Channel Data Link – Photron from Department of Integrative Biology, University of California, Berkeley., CA, USA). Uploaded by asemoknyo (1st April 2008) Accessed 23rd March 2010, URL: http://www.youtube.com/watch?v=aAu2f87QAQU
Video 2. “Flawless Victory!!! Baraka Wins!!!” by bcgeazy, (28th June 2007) Accessed 22nd March 2010 . URL:http://www.youtube.com/watch?v=tsjtdIQ4KqY
Patek, S. N., Korff, W. L. and Caldwell, R. L. (2004). Deadly Strike Mechanism of a Mantis Shrimp. Nature 428, pp.819-820 URL:http://www.nature.com.libproxy1.nus.edu.sg/nature/journal/v428/n6985/full/428819a.html (Accessed 27th March 2010.)
Patek, S. N., Korff, W. L. and Caldwell, R. L. (2005). Extreme Impact and Cavitation Forces of a Biological Hammer: Strike Forces of the Peacock Mantis Shrimp (odontodactylus scyllarus). The Journal of Experimental Biology 208, pp.3655-3664 (The Company of Biologists, 2005) URL:http://jeb.biologists.org/cgi/content/full/208/19/3655#REF32 (Accessed 27th March 2010)
Caldwell, R. L. and Hugh, D. (1975) Ecology and Evolution of Agonistic Behaviour in Stomatopods. Naturwissenschaften 62, No.5, May 1975 pp.214-222 (Springer Berlin/Heidelberg,1975) URL: http://www.springerlink.com.libproxy1.nus.edu.sg/content/r954162725487205/fulltext.pdf (SpringerLink date: 12th Dec 2004) (Accessed 1st April 2010)
Kleinlogel S. and White A. G. (2008) The Secret World of Shrimps: Polarisation Vision at Its Best. PLoS ONE 3(5): e2190.doi:10.1371/journal.pone.0002190 URL: http://www.plosone.org/article/fetchArticle.action?articleURI=info:doi/10.1371/journal.pone.0002190 (Accessed 1st April 2010)
White A. G. (2008) in “Weird Beastie” Shrimp Have Super-Vision, by Minard, A. (19th May 2008) National Geographic News. URL: http://news.nationalgeographic.com/news/2008/05/080519-shrimp-colors.html (Accessed: 1st April 2010)