Rich Mooi

Rich Mooi, curator of invertebrate zoology and geology at the California Academy of Sciences, writes from the Philippines, where he is surveying echinoderms off the coast of Luzon Island.

This is the most amazing place I have ever been in my 30 years of research. We are situated in Mabini, southern Luzon, at the edge of the Verde Island Passage, studying the marine biodiversity of this center of the center of species richness in the Indo-Pacific region. Each day starts with a series of dives, and ends in night dives that further reveal nocturnal denizens of the passage.

We have racked up more than 115 sampling visits over the past few weeks, yet surprises still keep us astonished. Like Mr. Gump and his box of chocolates, you never know what you’re going to get. Our team is finding a new species of sea slug per day and more new bristle worms (polychaetes) than we can process, and our expert on sponges from the Philippines National Museum has more than doubled the size of that museum’s entire sponge collection. Our mutually beneficial collaborations with a team of experts on reef-building corals from the University of the Philippines netted 50 or more staghorn coral species from a single location. The Verde Island Passage is living up to its reputation: The ocean vibrates with the cycles of living things inhabiting every nook and cranny.

I, too, have stories from my own area of expertise, the sea urchins — those spiky balls that occur everywhere here. Urchins belong to a group known technically as the echinoids. Echinoids come in two main varieties: One is more or less spherical, with long-spined forms, and is a conspicuous inhabitant of reefs and rocks. The most familiar of echinoids, these are sometimes informally referred to as “regular” urchins because the mouth on the bottom is surrounded by five regularly radiating rows of tube feet that converge again at the top of the dome-shaped body. These animals wedge themselves into crevices with their spines or, in the case of the black urchins that have long spines that can inflict damage to the unwary (fish or divers), live brazenly out in the open. Another large group of urchins might be called “stealth” urchins. These are less seldom seen, and keep mysteries of their own.

Rich Mooi

In a few weeks here, I have identified 42 species of sea urchins, about half of which fall into the “regular” category. This is staggering diversity when it comes to these animals. Among these is a real stinger of an urchin in the genus Echinothrix that is normally pale, with banded spines. I received an e-mail from a colleague suggesting that I look out for a red variety that could be a new species. Within hours, a diver brought me an urchin that looked sort of familiar, yet not so. The red variety had karmically appeared, and molecular and other work can now be done to determine if this is a new species in the genus. Although these large, relatively dangerous urchins are known throughout the Indo-Pacific, there has not been a new species of Echinothrix in over 230 years.

Rich Mooi

Rich Mooi

Rich Mooi

There are other ways of making new discoveries apart from finding new species. For many years I have been working on “regular” echinoids called hair-spined urchins. These are small-bodied, but with very long spines. The spines are as thin as or thinner than a human hair, even though they are made of the same limestone skeleton as the rest of the body. It’s as if these urchins have learned to “spin” limestone into fibers like we spin fibers of silica into fiberglass. Like fiberglass, the spines of these urchins are unexpectedly flexible. In spite of these fascinating attributes, this urchin remains very poorly known, and only a handful of specimens exist in all the world’s museums. The nearest record to the Philippines was 1,500 miles away as a fish swims, in Guam.

Another remarkable range extension was found for a species of fire urchins, so named because of a nasty sting deliverable by every spine on its body. So we have discovered major range extensions of some of the most mysterious and poorly known of all “regular” urchins found in shallow waters.

In my next entry, I will introduce you to the world of those stealthy “irregular” urchins. Sand dollars, sea biscuits, and sea mice have their own odd stories to tell.