Cruising along the muddy bottom we occasionally see isolated soft corals or sponges rising up from the benthos (bottom dwelling flora and fauna). In the absence of reef and rock, these animals provide the living space for many other smaller creatures. We sampled a hollow-stemmed gorgonian coral only eight inches tall that yielded over 100 individual crustaceans and represented at least seven species.

This is one of these gorgonians:

And this is a sampling of the crustaceans recovered from a single pink individual:

And what of the sea cucumbers from these deeper murky waters? We saw only two during our dive, but one was an encouraging find. It was Holothuria scabra, one of the two or three most heavily exploited and high-value species occurring in Madagascar (shown below). The typical price in Singapore for this species in 2003 was between US$40-56 USD/kilo dried, but it would not be unusual to get over $100/kilo in other markets.

Sea cucumbers have been heavily fished for centuries as part of a multi-million dollar food trade, with China as the principal center of consumption. Not surprisingly, many of the large sea cucumbers are rarer in Nosy Be than would be expected to occur naturally. Certainly this reflects how heavy they have been exploited, and unfortunately around the tropics this is the norm rather than the exception. The deeper murky waters where we found this animal are more inaccessible to fishermen, and the best hope for many of these highly sought after species may be their ability to thrive in habitats farthest from their reach.

Giant sea star found 87 feet deep near Madagascar

One week into our survey and we have catalogued close to 1000 different invertebrates (mainly echinoderms, mollusks, and crustaceans) and between 350 and 400 fish species. How many are new to science remains to be determined with the help of DNA sequencing and comparison with museum specimens. Certainly some will be new records for Madagascar.

Much of the area near our base of operation on the island of Nosy Be is shallow continental shelf, with maximum depth of 120 feet though possibly some deeper areas. For the most part we have been working the shallows, areas with extensive reef coral development and rubble produced by the devastating effects of cyclones that periodically hammer the coastline. Coral rubble is a gold mine of invertebrates; it has a lot of niche space in which all kinds of animals can take cover. Although our search for undocumented species in this habitat is far from exhausted, much of what we are seeing is becoming familiar from previous dives. So today we headed out to the deeper waters for some "muck diving."

We chose at random a site in the middle of the channel separating the islands, and followed the anchor line down to the bottom. The site turned out to be a fine muddy benthos at 87 feet. My first impression of this habitat was of a barren seascape, with not much to see but mud and detritus. Certainly there is neither the explosive color nor obviously high species diversity found on coral reefs. Upon closer inspection, however (which had to wait for the dust to settle that was produced by the action of my dive buddy's fins kicking up the mud) we discover many amazing an unusual animals that thrive in this kind of habitat. Among our discoveries today were giant sea stars we have not found elsewhere, some measuring two feet at their widest.

Our Malagasy colleagues, who have been diving here for decades, admitted this was the first time even they had seen these species. Few divers and even marine biologists venture out into these less "pretty" underwater environments, but clearly those that do are rewarded with unique wildlife only observable off the beaten path.