Sponges of the New Caledonian lagoon - IRD

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Sponges
of the New
Caledonian
lagoon
slow-growing and long-lived. In the Caribbean, hawksbill turtles (Eretmocheles
imbricoto) are major predators on sponges and probably are significant predators
on sponges in the Indo-Pacific region. Fishes, molluscs (especially nudibranchs),
starfish, plus many small reef animals will occasionally feed on sponges. While
large predators may be absent, there are often large popu]ations of small predators
living on and in sponges. If you cut a large sponge open, there is usually a large
assortment of small animals living inside. Therefore, the sponge appears to serve
as a hotel, sheltering many small mobile animals. Little is known, however, of the
relationship between the 'guests' and the 'host' sponge. Some of the guests may be
using the sponge as a safe haven, whereas others could be feeding directly on the
sponge tissue or stealing food as it comes into the canals.
Throughout the long period of sponge evolution, it is probable that sponges have
evolved mechanisms to prevent predation and competition. Some of these involve
the production of many compounds, which may be distasteful, thereby deterring
other animals from feeding, or the compounds may be toxic to potential predators.
These compounds have recently attracted the attention of scientists in the search
for drugs against human diseases or agricultural pests. This has led to considerable
interest by Orstom, which is concentrating on sponges in the search for drugs to
combat cancer, and diseases like AIDS and the common cold. The discovery of
some compounds, which have such useful activity has stimulated much interest in
the taxonomy of sponges and has been at least partly a catalyst for the production
of thiS book.