EGAD

Weekend Invertibrates

Back in Rehovot today, it's about 24 hours after I set out from Minneapolis, but my biological clock is supposed to believe that it's more like 32. Gave John a bit of a run-around on the way to the airport when I forgot my passport, but it's been an uneventful transit since then. So for want of anything more timely to report, I give you ... coastal invertibrates of the Red Sea.

From near the tidal pool, a common sand crab hanging out on the rocks, trying to look like a rock while it waits for food to wander by. This fellow seemed singularly unperturbed by my presence, which I take to mean that I'm doing something right in my nature photography technique. 2005:04:23 14:00:07.

Recall if you will, that I spent a weekend in the Sinai last month, hanging out on the beach and hiking in the mountains. I have a rather large backlog of photographs to sort through, which will make good filler material for the blog every now and then. On a good day I might even string them together into an interesting and analytic narrative, but today I'm just going for passably coherent filler, since I'm jet lagged and still a bit under the weather.

On any reasonably healthy beach, a fascinating tidal pool ecosystem develops with each low tide, during which smaller fauna colonize the standing bodies of water left behind in depressions on the beach. Since these areas are re-submerged with each high tide, a diverse array of aquatic flora can thrive there as well. They are similar in many ways to a reef in miniature: abundant solid attachment points and shelter from predators; plenty of sunlight to drive photosynthesis; periodically strong currents replenish the oxygen and nutrients in the water. However, life in a tidal pool is much easier to photograph, since all this takes place in water only a few centimeters deep!

Here a sea star is partially sheltered under a rock in one pool. Also visible is a hermit crab (in the shell on the lower right); the nearly transparent shrimp in this pool appear not to be discernable here. 2005:04:23 14:05:32.

Going out a little further, this beach turns moderately rocky before giving way to sandy seabed. In some areas, this develops into full-blown coral reef, but not here. However, plenty of interesting life inhabits this zone as well. The challenge is to photograph it, since without a submergable camera waves will interfere with any attempt to take pictures from above. In the Red Sea, though, this problem occasionally solves itself. Since the Red Sea is only tenuously connected to the larger oceans, very little wave energy makes it in through the Strait of Tiran, meaning that on a day when the air is sufficiently still the waves can die away completely for a time. The resulting silence is quite eerie for a beach, but this temporary lull allows for wonderful photographic opportunities.

On a rare waveless afternoon, an octopus strides along the rocky terrain just off shore. Shortly after this photo was taken, the animal noticed us and jetted away. We didn't see any of these when out snorkelling later, which suggests that they only come this close to shore when there are no breakers to disturb them. 2005:04:22 11:49:43.