Slugs of Madagascar
Every 5 or 6 years, we end up exploring someplace a little more exotic. This year, we decided to go to Madagascar, and we arranged for a driver and accommodations for about 10 days of overland travel and saw some incredible people, landscapes, and wildlife. We’re still sorting through the photos of lemurs, chameleons, villages, and vistas, and it is likely to take some time.
Of course, you don’t come to this web site for the lemurs.
Because we were traveling all the way to an island in the tropical Indian Ocean, I pushed for a stretch of diving at the end. When we were planning the trip, I asked our tour operator, Cactus Tours (an excellent Madagascar-based company) to arrange for some diving at the island of Nosy Be, at the north end of Madagascar. We ended up spending a few days in Nosy Be, and had three days and two night of diving on a sailing catamaran.
After bouncing around in a four-wheel drive for over a week, it was pure luxury to be on the boat. For just the two of us, there was a driver, cook, and a very experienced and knowledgeable dive master, all arranged through Madavoile Cruises. We had six excellent dives, and were completely blown away by the diversity of corals, fish and invertebrates.
Our dive guide, Nicolas, figured out pretty quickly that I wanted to see nudibranchs and sea slugs, and he did not disappoint. The photos below were taken with an Olympus Tough TG-4 camera, which is rated to 50 feet without a housing. Because the housing was clumsy, we took the unhoused camera as deep as 65 feet, which worked just fine despite its increasingly strident warnings. Identifications are based largely on a digital version of Gosliner et al’s “Nudibranch and Sea Slug Identification” and the Sea Slugs from Reunion Island Web site, which is an excellent reference for the southwest Indian Ocean. Please let me know if you believe a species to be misidentified.
Although we saw plenty of Caulerpa, Halimeda and other macroalgae, and looked very hard for Elysia, we came up empty. At Nosy Sakatia, we spent our last morning snorkeling with the turtles before we dove, and I was pleased to see a wide expanse of turtle grass (Thalassia) and manatee grass (Syringodium), which had some excellent growths of Halimeda incrassata.
Unfortunately, I did not get to spend hours searching the seagrass beds. Watching the biggest green turtles I had ever seen graze right in front of me was a nice consolation. It is hard to get a sense of just how big these monsters are from a photograph.
I did find one sacoglossan, Plakobranchus ocellatus, on the reef at Sakatia Arch. Unfortunately, the camera housing I was using for the dive had fogged, so it is a lousy photo. Just not the trip for sap-sucking slugs, I guess.
In addition to the plentiful slugs, there were quite a few flatworms pretending to be nudibranchs. All were in the genus Pseudoceros, and all were found in Humann and Deloach’s Reef Creature Identification book, which has an impressive section on flatworms.