Mantis
shrimps are in the order Stomatopoda,
and are marine crustaceans. They are roughly split into two different groups based on how they hunt for their prey: smashing, or spearing their prey to death.
Mantis
shrimps are essentially the Swiss army knives of the sea. They have appendages
that use a spring-loaded strike mechanism, which involves simultaneous
contractions of muscles in the ‘merus’, which, through a series of complex
steps, results in a final powerful release that pushes the appendages at force
towards prey. Their raptorial appendages vary in structure between species,
some specialized for spearing techniques and others specialized for smashing,
with hammer-like clubs.
Top Image - Florida Fish and Wildlife Conservation Commision
Bottom Image – Adapted from a photo by Professor Roy Caldwell. [Both Accessed 21 March 2014] |
“Spearers”
utilize the very end of their raptorial appendages called the ‘dactyl’ and
‘propus’, and use it to slice and snare evasive prey. Spearing mantis shrimps
are generally ambush predators, hiding in burrows dug out of the sand on the
sea floor. Most of the time, only their eyes and antellules will be exposed.
When an unfortunate creature such as a fish is to come within range of the
mantis shrimp, it lunges from its burrow to snare its prey and drags it down to
the safety of its burrow (deVries et al., 2012).
Image:
Photographer ‘diverdk’ on Flickr.com [Accessed 22 March 2014]
|
“Smashers”
tend to search away from their burrows and approach prey with harder shells,
such as other crustaceans. They also have been recorded attacking cephalopods,
including the Blue Ringed Octopus. They utilize both the spear tip and the club
of the ‘dactyl’ to deliver high force blows over short periods of time, or to
spear softer bodied prey (Patek, 2005). Due to their ability to deliver
such forceful blows, the smashing mantis shrimps are able to prey upon marine
creatures with shells, including clams, snails and crabs of various shapes and
sizes.
It was
originally thought that the spearing mantis shrimps struck at higher speeds
than smashing mantis shrimps, as scientists thought that speed was the
necessary component in catching quick, evasive prey. It was actually found that
the speed was not the primary component needed in a strike, but accuracy.
Mantis
shrimps are equipped with eyes that happen to be the most unusual in the animal
kingdom. They are mounted on stalks, and move independently of one another.
Mantis shrimps are able to see eight-channel colour vision, remarkable range
finding, linear and circular polarization vision, and luminance and form vision
(Chiou et al. 2008). These enable mantis shrimps not only to see everything in
their predatory strike, but also communicate with each other using body colour
signals. Colouring of the body in mantis shrimp species is thought to be
involved in recognition of their own or other species by the individual. In
mating rituals, it has also been seen that mantis shrimp fluoresce, which can
be detected by the many wavelengths that they are able to see. One of the most
colourful and well-known species is Odontodactylus
scyllarus, the Peacock Mantis Shrimp.
References
deVries,
M.S., Murphy, E.A.K., Patek, S.N. 2012. Strike mechanics of an ambush predator:
the spearing mantis shrimp. The Journal of Experimental Biology [Online]. 215,
4374-84. Available at: http://www.ncbi.nlm.nih.gov/pubmed/23175528 doi: 10.1242/jeb.075317.
[Accessed 22 March 2014]
Patek, S.N., 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 [Online]. 208, 3655 – 3664. Available at: http://jeb.biologists.org/content/208/19/3655.full doi: 10.1242/
jeb.01831 [Accessed 21 March 2014]
Chiou, T.H., Kleinlogel, S., Cronin, T., Caldwell, R. Loeffler, B.,
Siddiqi, A., Goldzien, A., Marshall, J. 2008. Circular Polarization Vision in a
Stomatopodal Crustacean. Current Biology [Online]. 18, 428-434. http://dx.doi.org/10.1016/j.cub.2008.02.066 [Accessed
21 March 2014]
Violent animals! Very cool. If you were to place a bet on a fight between a smashing mantis and spearing mantis, which one would you back?
ReplyDeleteDefinitely a smashing mantis. I think their speed would win overall and they are adapted to target hard-bodied prey. Spearers are more suited to softer-bodied prey like fish, I doubt they'd have much of a chance..
DeleteBrilliant description! Swiss army knives of the sea! The mantis shrimps are quite an extraordinary group of organisms and it’s no wonder many people find them fascinating. The videos are great to give one an idea of just how quickly they are able to spear/box their pray. Another great illuminating post about unique and unusual hunting techniques!
ReplyDelete