This page links to species of mantis shrimp we have observed at Kwajalein. The mantis shrimp order, Stomatopoda, is composed of several separate families, but we have few enough species that we have lumped them all together in the thumbnails below. While some species of stomatopods are instantly recognizable, others are variable in color and sometimes difficult to identify from photos. The group, however, is a fascinating one whose members possess some very interesting morphological and behavorial adaptations. A pair of their anterior appendages (called raptorial appendages) are folded up like those of a praying mantis (hence the common name), except that the joint articulation is opposite. That is, the appendages of a praying mantis strike downward, apparently to be able to clobber from above prey trying to fly away, while those of the mantis shrimp strike from below, apparently to hit the potentially softer underbelly of their prey. These raptorial appendages come in two forms, one a hardened club used to break shells of crustaceans or even the harder shells of clams and snails, and the other a comb-like row of long sharp spines used to impale prey. The shrimp bearing these weapons are called smashing or spearing stomatopods, and some have been given the common name of "thumb-splitters" by those unfortunate enough to handle them carelessly. The speed of the strike of particularly the smashing stomatopods is reported to be the fastest underwater strike and one of the fastest in the entire animal kingdom, several times faster than that of a praying mantis. (There is one terrestrial ant known to have a faster strike.) Another unique feature of stomatopods is their vision. These shrimp have multifaceted compound eyes that at least in some species allow each eye to see in binocular or even trinocular vision, allowing extremenly fine depth perception when both eyes are used and excellent depth perception even from only one eye. The eyes are on stalks that allow them to rotate in different directions. Some stomatopods see only in black and white, but others have as many as 16 visual pigments (compare that with the 3 humans have) and can see into the infrared and ultraviolet spectra. Some also can see polarized light, which may be useful for communication. By comparison, we mere humans are half blind. This and other fascinating information can be found at the Secrets of the Stomatopod site and in Debelius (1999).
Measurements were rarely taken in the field and animals were not collected, so any sizes given are usually very rough eyeball estimates often based on distant memories, and are provided only as a general guideline of what to look for. Estimated lengths include the body from head to tail, but generally not the anterior appendages.
We have made a few guesses on species and genera of some of our unknowns, but no doubt there are errors. We welcome corrections at uwkwaj@yahoo.com. Clicking on a thumbnail below brings up a page for that species.
Debelius
(1999)
Humann
& DeLoach (2010)
Roy's
List of Stomatopods for the Aquarium.
Ryanskiy (2020)
Stomatopoda
from Guam.
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