This page links to photos of marine sponges (Phylum Porifera) we have seen around Kwajalein and other atolls in the Marshall Islands. Sponges are abundant, growing on the bottom but also on man-made structures such pier pilings, buoys, mooring lines and boat hulls. They are filter feeders, usually drawing water in through many small holes called ostia, filtering that water for planktonic food, collecting that water in central cavities and pumping it back out through larger holes called oscula. Species can be thick and massive or thin, encrusting the surfaces they are on. Many, perhaps most are sensitive to sunlight and grow in area with subdued light or that are dark, such as in shaded ledges and caves or under rocks. The photos below show only a sampling of the marine sponges in the Marshalls. We did not attempt to photograph most of the sponges. In many cases, the photos we did get were taken in the old film days, when cameras were largely restricted to 36 exposures per roll of film. Usually we would save two or three frames at the end of the roll until the very end of the dive, since you could be sure that once you used up all your film, you'd see something you absolutely HAD to get a photo of. So quite often, with air running out, we'd have to quickly take those last few shots of just about anything to keep from wasting film. So that was how we got many of our sponge, tunicate or coral photos. With the exception of a few well known species, sponges are quite difficult to identify, with variable shapes and colors that often make one species look like several. Our names came from several references, some books and some websites, but because of the variability, our specimens usually do not exactly match those from the references. Most of these IDs must be considered tentative, but we thought it worthwhile to at least make the images available.
The thumbnails below link to pages with additional, larger photographs.
Demospongiae
Calcarea
Major references used:
Colin
& Arneson (1995)
Gosliner
et al (1996)
Hoover
(1999)
iNaturalist
Marine
Biodiversity Survey of Guam and the Marianas - Porifera
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