a piece of algae-covered living rock in the shallow-water zone of a coral reef near cebu, philippines; on
closer examination a reddish Odontodactylus scyllarus
can be seen close to calcareous algae of the same color,
peering motionless from its abode and attentively
observing its surroundings with its faceted eyes.
Numerous observations exist regarding stomatopods and other shrimps living together, without
there being any conclusive explanation of this
to date. Debelius (2000) and Kuiter & Debelius
(2009) depict mantis shrimps with a wide variety
of other crustaceans, for example Stenopus tenuiro-stris, Thor amboinensis, and Periclimenes imperator,
as well as additional Periclimenes species. Werner
Fiedler has also taken photos of this type of relationship in
Sulawesi (Indonesia). So why doesn’t the mantis shrimp
eat the shrimps, which are tiny in comparison to itself?
The obvious supposition is that they clean the bodies of
the stomatopods, but Debelius (2000) rightly points out
that these predators in fact perform very thorough maintenance of their own bodies and are perfectly capable of
reaching every part of their anatomy. There is thus no obvious need for any sort of cleaner service.
But nevertheless, as the accompanying photos show,
it can be seen that the shrimps in fact clamber around
even between the eyes and mouthparts and collect fine
particles of food, and the sheer number of such photos
is evidence that we are not dealing with isolated cases.
So what benefit do these two different organisms obtain
from their shared existence? Helmut Debelius sees the
benefit to the shrimps as consisting solely of food intake:
mantis shrimps construct their burrows in fine sand, ce-
menting the grains with a mucus secretion so that the
construct doesn’t collapse. This secretion may perhaps
attract the shrimps via their olfactory sense. In addition
mantis shrimps regurgitate indigestible food residues
such as fish scales, and this could likewise be responsible
for the presence of the little “commensals”.