Chemical Defenses of Cryptic and Aposematic
Gastropterid Molluscs Feeding on their Host
Sponge Dysidea granulosa
Mikel A. Becerro
&
John A. Starmer
&
Valerie J. Paul
Received: 30 March 2005 / Revised: 22 September 2005 /
Accepted: 28 September 2005 /Published online: 23 May 2006
#
Springer Science + Business Media, Inc. 2006
Abstract Numerous opisthobranchs are known to sequester chemical defenses from
their prey and use them for their own defense. Information on feeding biology is
critical for understanding the ecology and evolution of molluscs, yet information on
feeding biology is still scarce for many groups. Gastropterid molluscs are often
found on sponges, but there is controversy as to whether they are true sponge
feeders. On Guam, we found the gastropterids Sagaminopteron nigropunctatum and
S. psychedelicum on the sponge Dysidea granulosa. They seem to rely on contrasting
defense strategies as S. psychedelicum has vivid colors, consistent with the warning
coloration found in many chemically defended opisthobranchs, whereas S.
nigropunctatum is highly cryptic on the sponge. S. nigropunctatum is avoided by
the pufferfish Canthigaster solandri in aquarium assays. We analyzed the secondary
metabolites of the two species and found that both share polybrominated diphenyl
ethers (BDEs) with their host sponge D. granulosa. S. psychedelicum and S.
nigropunctatum sequester the major BDE in the sponge and accumulate it in the
mantle at approximately the same concentration as in the sponge (4.03 and 2.37%,
respectively), and concentrate it in their parapodia at over twice the sponge
concentration (7.97 and 10.10%, respectively). We also detected trace amounts in
the mucus secretion of S. psychedelicum, and quantified significant amounts in the
mucus (1.84%) and egg masses (2.22%) of S. nigropunctatum. Despite contrasting
color patterns displayed by the two gastropterid species, they seem to share a similar
J Chem Ecol (2006) 32: 1491–1500
DOI 10.1007/s10886-006-9064-5
M. A. Becerro (*)
:
J. A. Starmer
:
V. J. Paul
University of Guam Marine Laboratory, Mangilao, Guam 96923, USA
e-mail: mikel@ceab.csic.es
M. A. Becerro
Center for Advanced Studies (CEAB, CSIC), E-17300 Blanes (Girona), Spain
J. A. Starmer
Florida Museum of Natural History, University of Florida, Gainesville, FL, USA
V. J. Paul
Smithsonian Marine Station at Fort Pierce, 701 Seaway Drive, Fort Pierce, FL 34949, USA