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The 2011 Philippine Biodiversity Expedition 

May 21, 2011

When it comes to echinoderm collagen, there is always a catch

I was taught a lesson in self control the other day, while snorkeling in an area that had lots of rocks. In between the rocks were lots of crevices, and in those crevices we found some of the most magnificent of all the sea urchins. The self-control of the sea urchins (which I will talk about in a moment) inspired self-control in me with respect to scientific collecting as well.

The aforementioned magnificent urchin goes by the mellifluous name of Heterocentrotus mamillatus, and here is the creature, securely jammed into its urchin home:


That is the correct spelling of the species name. Some of my colleagues might be tempted to put an extra “m” in there to make it “mammillatus“, but that is not what the original author of the name, none other than Carl von Linné (a.k.a. Carolus Linnaeus) himself, had in mind back in 1758. The reference is to more or less the same mammalian attribute in either spelling, but there are nuances of the usage that have to be respected, and Linnaeus knew that. He was nothing if not a smart guy who knew his human anatomy. He wanted the mammalian reference in the name because when cleaned of its spines, Heterocentrotus mamillatus displays the most beautiful of smoothly domed, glassy spine tubercles that reminded him of… well, a certain mammalian attribute. Maybe he had spent too much time in the field. The big, heavy spines of Heterocentrotus sit neatly on end, one spine over each of these tubercles.  Think of balancing a baseball bat on a half-buried baseball. In the base of the spine is a neatly polished little hollow, or socket, making a finely honed ball and socket joint that any car mechanic would greatly appreciate. To think that this piece of urchin machinery, with its very fine engineering tolerances, is made basically of limestone is simply to wonder at it all the more.

At this point I feel it necessary to mention that you might have encountered these spines, minus the urchin, in various tropical places where a certain type of wind chime might be offered for sale. Turns out that when a Heterocentrotus spine is gently tapped with a hard object, such as another spine, it sounds with a gentle ring that some find pleasing to the ear.

Frankly, I am not a fan of wind chimes of any kind. The only place I have these big spines installed in my lab in San Francisco is in the form of my “Acme Echino Quake Detector”, which is a strange composite “decoration” that hangs from the ceiling with my hope that it will jangle in time to warn of the next “big one”. Otherwise, I don’t think the natural and soothing sound of any breeze that would activate a set of wind chimes needs any enhancement whatsoever, as the breeze has its own kind of auditory beauty. Humans can be strange animals sometimes.

Before people get upset, I should also chime in that Heterocentrotus spines for the “wind music” industry are not usually harvested from the living animals.  When the urchin dies, hopefully after a long and happily productive life (however that is measured by urchin standards), the spines remain so durable that they wash up in large numbers on certain beaches, where they can be picked up and employed in the noble noisy cause described above.

The genus name, Heterocentrotus, is in reference to these incredible spines, which come in two basic varieties: big and strong, and small and stubby. You can see these in the close-up below:


“Hetero” means “different”, so this urchin is named for the fact that is has two very distinct types of spines. As I’ve said before, I love it when scientific nomenclature makes sense. But if you really insist on a common name for this creature, you could call it the “slate pencil urchin”. Does that feel better? In my opinion, it shouldn’t.  There is a reason that biologists coin scientific names. How many of you out there have ever encountered a “slate pencil” in this day and age of electronic gadgetry? Would you even recognize one if it flew up your nose and did the lambada? Heck, even pencils come in mechanical form now, and not to write on slates either. And just to make matters worse, sea urchins in a completely different order, the Cidaroida, are also called “slate pencil urchins”. So much for common names.  Heterocentrotus it is. It’s really not that hard after all. If a 5-year-old can remember “Triceratops“, an adult can surely come to grips with “Heterocentrotus“.

Speaking of grips, Heterocentrotus is nearly impossible to remove from its stony home. Actually, make that fully impossible, at least without dynamite, a crowbar, or otherwise hurting the poor thing. The primary reason for this is in the spines, which are, appropriately enough, called primary spines. As I mentioned, primary spines sit on a ball and socket joint. They are held down to the urchin’s skeletal test by a ring of muscle that can be differentially contracted around the ring to point the spine in different directions. This is a handy attribute to have if you are nearly spherical, and want to point your spines at an incoming enemy, or to wedge yourself into a crevice in the rock. However, muscles are metabolically expensive to run, and sea urchins are not what you would call physiological dynamos. So there must be something else going on to keep these animals in place 24/7, safe from dislodging by waves, predators, or marauding echinodermologists.

Turns out that inside the ring of muscle is a second ring of connective tissue, which is not muscular, but composed of a connective tissue made of collagen. This tissue is ubiquitous in animals, and is usually used to connect muscles to bone, or bone to bone, amongst other uses. In the case of the sea urchins, the collagen is found in a ring just inside the muscular ring.  I’ve shown this in the diagram below (which I have modified from a couple of images in Clarke and Rowe, 1971).  In this diagram, all the spines have been removed except one primary spine, so that you can see the connection to the surface of the body, or test:


The collagen in this inner ring is rather special — it’s so-called “catch collagen”. It’s stiffness is under voluntary control by the sea urchin, probably through nerve action. When the urchin wants to move the spine, the collagen ring becomes soft and pliable, allowing the muscles to place the spine… just so… perhaps to brace against the rocky wall of a cozy reef nook or cranny. Then the urchin stiffens the collagen in the inner ring, effectively locking the spine into position. The muscles can now relax, and ta-da! A powerful brace is in place in the space with energy of zero trace. With a bunch of these spines employed in this way, the urchin simply canNOT be dislodged without breaking something — usually the spines. But in the case of Heterocentrotus, the spines are so big and so powerfully built, any prying force strong enough to make the spines move away from the rock wall usually ends up breaking the urchin’s test. And that is truly a shame, given just how beautiful this animal is.

A few other last words about catch collagen. This substance is part of a group of such tissues in echinoderms known generally as “mutable collagenous tissues”. These have been found in all the major echinoderm groups. In fact, alongside the special stereom version of calcium carbonate used to make echinoderm skeletal elements and basic 5-part symmetry in adults, I would list mutable collagenous tissue as a unifying characteristic of the phylum. In the body wall of a starfish, for example, mutable collagenous tissues can be softened to allow the animal to glide neatly over uneven surfaces, then stiffened to lock the animal into place in an infinite number of what look like the most awkward poses that would be the envy of any acrobat. Such staying power, with no energy output! In sea cucumbers, we have arguably the most extreme usage of mutable collagenous tissues. The entire body can soften to allow movements into the tiniest of holes and cracks, yet stiffen again in an instant to hold the front end of the animal up to filter feed with elevated tentacles around the mouth, or wedge the animal into a small crack.

Okay, I lied. There is one more thing I wanted to add. Turns out that there is at least one other place where similar mutable collagen can be found. This is between the pelvic bones of human females (and perhaps other mammals). One of the many hormonal changes that happen in women during child-bearing is the softening of this connective tissue to loosen the bones in the pelvic girdle, allowing them to move a bit relative to one another. With a 10-pounder in the womb, many women have been the perhaps unknowing, yet ever-so-slightly happier beneficiary of collagenous tissue softening. With all that yelling going on, most women aren’t thinking about that during the joyous occasion of childbirth, and who could blame them?

(Almost) all of this ran through my head as I looked at Heterocentrotus locked into its home, and after a few attempts to brute-force them out of there, I gave up. It felt like picking the rarest and most beautiful of flowers in the woods with a weed-whacker.


Filed under: Mooi,Philippines,Shallow Water — rmooi @ 3:24 am

May 18, 2011

Urchins are really into rock

I’m thinking that maybe there is a career in sea urchin dentistry.

While working at Sepok Point today, I came to realize that most of the biomass in sea urchins in the Verde Island Passage is arguably in the form of Echinometra mathaei, also known as the rock boring urchin.  The concept of a boring urchin is not new to my colleagues here, who are very gracious in tolerating my windy stories about what I think are remarkable animals.  However, Echinometra really does bore — right into rock.  It does this in part by abrasion from its formidable spines, but mostly by using its teeth.  Urchins actually have five teeth, mounted in a 5-part, radial jaw that can open and close like the chuck of a drill.  This jaw apparatus is known as Aristotle’s lantern, for reasons that are obscure and part of a strange history of urchin nomenclature.  But we’ll let that go for now or this blog entry will end up being a treatise, not a nature nugget.  Suffice it to say that the mouth of the urchin is situated on the bottom surface of the globose body, and large enough to allow protrusion of the Aristotle’s lantern so that it can chew on, um… the rock.

The 5 teeth of an urchin are sharp and chisel-shaped at the tip. Although they are largely made of limestone, the teeth are hardened by “doping” this limestone with magnesium, a process known as dolomitization.  The term, incidentally, derives from an Italian mountain chain known as the Dolomites.  The mountains are very hard limestone with… high magnesium content.  Who would have thought there was a connection between sea urchin dentition and mountains in Tyrol?

Anyway… these hard little teeth can do a lot of damage to rock, especially over the lifespan of a sea urchin.  Here is the culprit, removed from his (or her — it’s hard to tell from the outside) boring life in the rock:


In spite of the hardened teeth and fierce-looking spines, these little fellows are gardeners.  Sort of.  They don’t chew straight down into the rock, but make a channel, or a groove in the stone.  This channel is enlarged as the animal grows, and as it harvests its food.  This consists of algae growing in the channel.  Bare surfaces don’t stay that way for very long in the sea.  Algae is a very quick colonizer of newly exposed surfaces, including those chewed to nakedness by busy little urchin teeth.  As the urchin chews, it removes a bit of the rock along with the algal food, thereby doing two jobs — making a protective channel in which to live, and getting nutrition from the algae growing inside this home.  Soon, the rock can look a bit like Swiss cheese:


When the algae at one end of the channel are all eaten, the urchin moves along to the other, allowing regrowth of the plant cover.  By the time the urchin gets to the end of the channel, there is enough regrowth to make it worthwhile to move slowly back to the other end again, munching the newer algae as urchin inches along.  The rock is hard, but hey, the urchin has all day.  There is some evidence to suggest that individual urchins can keep this up for decades.  In light of that supposition, it’s no wonder that a perfectly good coastline can start to look like this for much of its length:


Which brings us to the question of urchin dentistry.  Now that I think of it, maybe the idea of being an echinoid dental practitioner needs some rethinking.  Besides being very hard, sea urchin teeth are advanced along the inside of the jaw as they wear out, providing fresh tooth tip as the old tip erodes away.  Urchin teeth are very cleverly designed as long shafts of tightly packed, minute plates such that as these flake off the worn end, they leave a fresh, sharp edge.  No need for night guards or other hideous plastic dental aides to prevent wear from gnashing or grinding.

One could say that the teeth are boring, but never dull.

Along some parts of the Mabini coast, I have noticed that young Echinometra start out in less boring accommodations.  They crawl into a dead barnacle, which has become a shell of its former self:


Presumably as they outgrow this living situation, the urchins crawl out of the barnacle and start a new channel, or get into an old groove left behind by an urchin who has gone on to that great cheeserock in the sky.

I should mention that there is an urchin that does burrow straight down into the rock, making a cylindrical shaft in which it can live like Timmy stuck in a shallow well.  This urchin, Echinostrephus aciculatus, has no need for rescue from Lassie, though, as it is perfectly shaped to fit into its tiny well, with the spines sticking out ever so much:


How Echinostrephus manages to make this amazing vertical shaft, which is several times as deep as the urchin is high, is not fully understood.  Presumably they use their Aristotle’s lantern as well.  The shaft of the boring is long enough that when disturbed, for example by an urchin-hunting echinoderm biologist, the urchin quickly skootches (to use the highly scientific term) down into the hole.  The animals are nicely designed for this.  The body is slightly conical, with a narrow end pointing downwards.  This end is furnished with lots of strong tube feet that pull the urchin downward.  The spines on the bottom of the body are very short, as opposed to the ones on the more exposed top, as can be seen in this laboriously extracted captive, flipped upside down (i.e. mouth upwards):


How this stationary urchin makes it’s living is not understood either.  Some claim that it snags bits of drifting food with the long, exposed spines.  One has to question whether that is enough.  They can’t farm like the Echinometra does, because it’s too dark down there in the recesses of the bore hole.

As usual, nature leaves me with no recourse but a fascinated shrug.

Filed under: Mooi,Philippines,Shallow Water — rmooi @ 8:57 am

May 6, 2011

There’s just some sting about you…

This may surprise some of you out there, but I hear a lot of talk about sea urchins.  Especially from divers and snorkelers who’ve had the good/bad luck of encountering these gorgeous beasts.  The good luck is in observing some of the strangest of all the Earth’s marine animals.  The bad luck is in getting a bit too close to certain kinds.  I would like to highlight the latter concept a little bit, and perhaps clear up some of the misinformation out there.  Or simply add some information that isn’t all that easy to come by, even though urchins are among the most common and conspicuous animals you can see on a dive or in a tidepool.  Doing this during the Expedition is easy because, well, the diversity of the urchins here is pretty amazing, and they’re right out there off the place where we are staying in the case of most species, especially the ones who can cause some damage.

To recap, sea urchins (Echinoidea) are in the phylum Echinodermata (“echino” = spiny; “derm” = skin).  The urchins are related to things like starfish, brittlestars, sea cucumbers, and sea lilies.  The most familiar of the sea urchins are globose things, adorned with spines distributed over the body.  The shape of the urchin is maintained by a skeleton of tightly sutured columns of plates made of a type of limestone (a.k.a. calcium carbonate) secreted as a biological form of calcium carbonate called “stereom”, making a structure not unlike your skull in that it is covered with skin.  In urchins, this skin, or epithelium, even forms a thin layer over all the external appendages, including the spines.  The columns of plates are arranged in a radiating pattern based on five.  Why five is a subject for another day, perhaps.  Nevertheless, this is a powerfully unique way to identify an echinoderm.  Look for that 5-part radiating symmetry.  The mouth of a sea urchin is on the bottom, and the anus is on the top.  Because the skeleton is technically internal to the epithelium (and not external like the shell of a snail or clam), it gets a special name, the “test”.  There are lots of puns I could make here, but I’ll largely refrain and instead only indicate that terminology tests us all at times.  But new terms add precision, and that’s what science is all about.  So test it is.

Back to stinging.  It always startles and pleases me to learn just how many divers have learned the genus name of a sea urchin:  Diadema.  Necessity is the mother of learning, I guess, because the memory of the name is almost always linked to a negative encounter with this black-spined urchin that decorates so much of the world’s coral reefs.  I actually really like this animal, but this is not a unanimously held reaction.  However, with a little caution and awareness of where your body parts are while drifting over a mass of Diadema, you can enjoy the encounter quite unscathed.  I’ve been collecting and observing these guys for many years, and I’ve only been hit once in a way that really mattered.  It served to instill respect that I hold close to this very day.  Most of the black urchins with the really long spines belong to the genus Diadema.  There are two common species of Diadema in the Philippines’ reefs.  Here they are:


The one on the left, D. setosum, is arguably the most common species ’round these parts, and is easily distinguished from the one on the right when seen alive and under natural light by the amazingly bright red ring in the little raised area on the top of the body (called the anal sac).  In both species, there are beautiful patterns of iridescence on the top of the test, and this makes urchin-watching just that much more special.

When hidey-holes under coral rubble are available, D. setosum tends to be solitary and able to defend against attacks (usually by triggerfish if anecdotal reports hold) by directing spines outwards.  However, out in the open they become more gregarious, gathering in small gangs of nervous pincushions, with the spines just touching to maintain their own respectful distances, spines constantly waving a little, particularly towards changes in light and pressure waves from passing animals such as fish or divers.  The effect can be dramatic, with just the right hint of menace.


Look, but don’t touch.  The long spines are very, very sharp, and come to a point so fine that it’s hard to see precisely where they end in a watery medium where distances can be deceptive to start with.  The spines can penetrate flesh so easily and quickly that once you feel it, it’s way too late.  You’ve been perforated.  More than likely, the spine (or spines, if you are really unfortunate) will break off in the skin.  You can try to pull them out, but the delicate and easily broken structure of the spine (which is hollow) makes that difficult.  Most people know about the barbs, but what they don’t realize is that the barbs don’t point backwards toward the animal, but towards the tip of the spine.  So the damage is done going in.  The other common misconception is that these spines are poisonous.  It only feels that way.  Most of the post-encounter discomfort comes when tissues inside the hollow spine start to decompose and attract bacteria.

And remember that epithelium I mentioned?  It also can break down and cause infection in the wound. Best way to deal with that is to immerse the afflicted body part in vinegar.  This does three things.  It makes the urchin tissues inert to bacterial feasting, kills the bacteria themselves, and dissolves the spine skeleton, which is also made of the calcium carbonate stereom described above for the plates in the test.  Being limestony, this material fizzes and dissolves readily in any acid such as vinegar.  Vinegar adds to the hurtin’ at first, but trust me, it helps and greatly reduces future damage that can be caused by leaving the spine in there whole.  If you don’t have vinegar, you can also roll the skin around the spine or tweeze the spine in the wound until it crushes up into smaller pieces for your natural immune system defenses to deal with.

Although the long spines of Diadema are not venomous, there are toxin-bearing spines on all members of the family Diadematidae, to which Diadema belongs.  In Diadema, these are relatively short, very sharp (yes, even sharper than the long spines), and almost never reached by an errant hand or foot or whatever, because you hit those long “guard spines” first.  That generally keeps you from reaching the stinging spine layer, unless you are really unfortunate and set up for a trip to the hospital because you put all your weight down on a Diadema.  Each of these shorter spines has a slight swelling at the tip where gland cells in the epithelium make and accumulate a toxin that causes a real, honest-to-goodness sting.

Although these gland-bearing spines are hard to reach (or even see) in Diadema, they are really prominent in another diadematid genus, Echinothrix:


Again, we have two species common in the Philippines.  E. calamaris has lighter spines, with beige or brown on the test, a nicely speckled anal cone (not a phrase you will see everyday), and very obvious and exposed, light brown spines tipped with poison glands, as in the close-up below (red arrow).


Note that the long spines of this close relative of Diadema are not sharp.  In fact, they are hollow with thin walls, like a straw with the end closed off.  In the juveniles, these spines are so large relative to the test that the urchin looks like it’s carrying little, narrow vases sticking out from its test.  Weird.

The other Echinothrix, which is very black with very nice, blue iridescent patches on the test, also has these shorter, poison-bearing spines.  You can see this iridescence and the poison glands (red arrow again) well when you get close up.


Then there is the fire urchin, Asthenosoma varium.  This is an urchin whose characteristics are so unusual I just have to tell you about it.  It’s also common in coral reefs just about everywhere.  Nature has found a special way to tell us “do not touch this animal”.  The bright colors might be inviting, but when you see that in nature, it usually hints at something dangerous.   This lovely photo is courtesy of Terry Gosliner, who has the same respect for this relatively large and powerful stinger as I do:


The test of this urchin, which can exceed 20 cm across, is flexible because the plates that make it up are separated by connective tissues that allow the plates to hinge against each other.  The urchin keeps its shape by gently inflating itself with sea water, but if you poke it (use something other than a body part, please), it yields a bit like a crunchy balloon.  The fire urchin uses this feature to get into crevices, and possibly also to economize on the metabolically expensive calcium carbonate that other urchins use to make up their stiffer tests.  This isn’t so much a factor in coral reefs, where dissolved calcium carbonate is relatively abundant.  But this urchin species has as its closest relatives a bunch of equally bizarre forms that live in the deepest parts of the ocean.  Evolutionary studies show that the ancestors of the fire urchin live in the abyss where calcium carbonate is harder to come by and to shape into urchin skeletal parts, selecting for species with thin, flexible tests in which calcium carbonate is used sparingly.  And guess what?  Those deep-sea relatives of A. varium compensate for the relative lack of an armored test by having the worst stinging capability of any urchin that I know.  I got hit by one in my left middle finger while doing deep-sea work in the Bahamas — just a tiny pinprick of one spine — and my left arm was useless for several hours.

Here is a close up of the spines on a fire urchin.  Most of that blobby, balloon-like tissue on the spines is filled with toxin.  Never pick up a fire urchin.  There is some evidence to suggest that you could go into shock if enough spines zap you at the same time.


Finally, I would like to mention one more stinging urchin with a difference.  This one hurts a lot, but not because of the spines.  The so-called “flower urchin”, Toxopneustes pileolus, is another one very pretty to look at, but deserving of respect:


The flowers are not spines, but a special structure unique to urchins called pedicellariae (for you sticklers — pun intended — out there, the pedicellariae on starfish are an independent evolutionary invention and only superficially similar to urchin pedicellariae). Pedicellariae (singular: pedicellaria — not “pedicellarium”) are ice-tong-like pincers mounted on the ends of stalks interspersed all over the test among the spines.  All urchins have pedicellariae, but they are usually small and inconspicuous, and too small to do any damage unless you are a tiny barnacle larva trying to find a nice home to stick to on the top of a sea urchin.  This is the usual type of thing that pedicellariae are used to defend against.  In Toxopneustes, the spines are very short and not very sharp.  This urchin protects itself from larger animals with the grossly enlarged pedicellariae instead.  Although they look like flowers, inside the pink fleshy bit that makes the “bloom” are three tongs that meet together at their points when the “flower” closes, tearing a hole in the transgressor’s flesh and injecting a toxin into the wound:


You can tell when the animal is all worked up and in the urchin equivalent of “DEFCON 1″ when the whitish spines lie down to expose the open jaws of the pedicellariae.  Put your hand on that and you’ll get a powerful dose of toxins from several pedicellariae at once.  A complicating factor is that this urchin, like many other species, likes to cover itself with bits of coral rubble, sometimes making it hard to see in the shadows.  Still, a beautiful animal and always interesting to see in its native habitat. It’s a real favorite of underwater photographers with an interest in abstract art.

So that’s my primer on stinging urchins.  I wanted to call this blog, “Oh test, where is thy sting?”, but I wasn’t sure if that might have been a bit unforgivable — or even obscure.  Heck, I don’t know my Shakespearean sonnets or Corinthians either.


Filed under: Mooi,Philippines,Shallow Water — rmooi @ 10:41 pm

May 3, 2011

Summer of underwater slither

Been trying to find a few moments to post this, but the pace has been a little high lately.  We’ve hit many new sites since I had my first ever encounter with this gorgeous animal, and there were some exciting things to process back at the “lab” (which consists of some tables back at Club Ocellaris).  Been making great progress on the sea urchin and sand dollar fronts, but that’s not the subject of this entry.

I was searching for and collecting echinoderms around a tiny, rocky outcrop that came to the surface to make a raft-sized island at a site called Ligpo about a 45 minute boat ride from the aforementioned “lab”.  Some movement in a crevice that connected with the surface caught my eye. Turned out to be a “lifer” for me, a sea snake.  I’m an echinoderm biologist, so my powers of identification of these things with bilateral symmetry and a backbone are a bit stretched, but I believe this to be Laticauda colubrina, the yellow-lipped sea snake.  Forgive me, herps people, if I have that incorrect.  Nevertheless, I spent about 10 minutes watching this magnificent animal watching me.  I am told that if they have a brood nearby, they can get a little more “interested”, and there were points at which the coiling and aiming behavior of the snake seemed a little bit more than just curiosity, so I couldn’t help but wonder if she(?) had eggs somewhere on that island.


Sea snakes are related to the cobras, and their venom is at least as potent, if not more so.  Like all snakes, they breathe air, and need to come to the surface to respire.  Their tails are flattened from side to side (hence the genus name: “lati” for compressed from side to side; “cauda” for tail — scientific names always make sense at some level).  I am told that these animals are de facto harmless, but should be “treated as venomous”, whatever that might mean in terms of snorkeling in the snake’s native habitat.  All the authorities agree that they seldom bite.  “Seldom” implies that there are instances, and I didn’t want to add to that small dataset myself, and exercised caution.  The movements of the snake were graceful and purposeful as it took a few gulps of air, then quietly and quickly moved down the crevice and across the soft coral masses below me to go hunting for some lunch.

Just had to get this out there in this, the Academy’s summer of slither.  Looking forward to my next encounter with one of these fantastic animals.  Maybe at the Academy?  Wouldn’t it be great to have one in the exhibit?


Filed under: Mooi,Philippines,Planning — rmooi @ 4:22 pm

April 30, 2011

Collaboration in the Philippines

With a solid couple of days of discovery behind us, patterns already begin to emerge.  It is always that way when a group of like-minded people get together on a mission, especially one for which a major purpose is to gather expertise in an intense environment of exploration.  So when I say “like-minded”, I mean this in only the general sense of wanting to explore and disseminate information about biodiversity.  From here on in, the joys and value-added are all in the synergy of squeezing together people with less like-minded backgrounds and different expertise.  Collaboration.  Different search images, different approaches.  The result is always greater than the sum of the parts, and the 2011 Philippines Biodiversity Expedition has this firmly in mind as part of its design.

The natural world is like this too.  Organisms with very different evolutionary backgrounds come together to encourage systems and interactions in ways we have still to try and figure out.  One thing is very clear.  In the sea, everything lives on everything else.  Or nearly so.  Some organisms use others as substrates to which to attach.  Others find protection among stinging bits of the host.  And so on.

A seemingly minor observation about a strange and not very well studied little sea biscuit (a flattened sea urchin closely related to the sand dollars, family Clypeasteridae) serves to illustrate not just inter-organismal collaboration, but that among scientists with very different interests in being here in Mabini.

I have had a long-time interest in sea urchins, sand dollars, and relatives such as the sea biscuits, and my earliest work was to study how these animals feed, and upon what.  Turns out that things like sea biscuits really like to eat sand and the things living in it.  So while I was here finding specimens of one species, Clypeaster reticulatus, I couldn’t help but notice that in the hollow space around the mouth on the underside of this little sea biscuit, there were dozens of odd little stars packed in like tiny little medieval mace heads:


This photo, taken today, shows a Clypeaster reticulatus flipped over onto the sand (by me) in order to show the tiny little stars in a depression around the mouth, which is obscured by the stars.  I had never seen anything quite like this before, but it didn’t take long for me to realize that this was food of some kind (not baby urchins), being stored for consumption by the Clypeaster.  Michele Weber (UCLA), who is a visiting expert on single-celled algae that live symbiotically in corals and other organisms (yet another example of synergies set up by collaboration), immediately recognized these as calcarinid foraminifera.

Whoa.  What are those?  Well, it turns out that sand, especially coarse sand, is full of life.  One of the forms of this life is a group of tiny, often microscopic amoeba-like forms called foraminifera.  They are single-celled, and live in minute houses made of limestone that they secrete around themselves, much like a snail makes a shell.  In the case of these little calcarinids, the house has big spikes on it, making it look like a little star.

The “nature nugget” thing here is that calcarinids of this type are also symbiotic with tiny, single-celled plants called diatoms, which are usually the natural food of sand dollars and sea biscuits.  Diatoms, being plants, make their food by photosynthesis, and therefore need access to sunlight.  So the calcarinids themselves need to be close to the surface of sand, which puts them within detection range of the little sea biscuits that like to eat them.  The sea biscuits carefully and deliberately select them from the rest of the less-interesting and presumably less nutritious sand grains, and pile them up in the unusual depression around the mouth.  In Clypeaster reticulatus, this depression is unique among the 40 species of the genus in having almost no spines, making more room for the much spinier calcarinid foraminifera.

The calcarinid-diatom collaboration makes a whole new set of relationships possible.  The collaboration among scientists such as Michele and myself on the Expedition makes it more possible to understand some of these relationships right here, on the ground.


Filed under: Mooi,Philippines,Shallow Water — rmooi @ 9:48 am

April 28, 2011

Getting a taste for marine discovery

At last, the vans are loaded with box after box of equipment, dozens of pieces of luggage, leaving just enough room for the dozen of us. As I write, we are on the highway south to Batangas at a slightly more snail-like pace than most of us would like, as eager as we are to get into the water for the first time.


Bob questions the driver about his light foot on the throttle

The highway from Manila to Batangas has been greatly improved in recent years, but we seem not to be taking full advantage of that. However, given the tonage of stuff in the trucks, maybe this nudibranch-like speed is more appropriate than the usual way I drive on 280, the autobahn of San Mateo.

We have been joined by two students from the Marine Science Institute (MSI) at the University of the Philippines. Much to my personal delight, both of them have a passion for sea urchins, and I expect lots of happy conversations with them during our hunt for the wily echinoids that form the focus of my work here.

I am certainly not the first to make the observation that in order to keep on learning, you need to have students. Already, I am learning from Inggat and Bryan. They work with a species of sea urchin harvested (and in some places, cultured) here in the Philippines for food. Aficionados of sushi will recognize this as uni, and it is best explained as the roe of sea urchins. It is, judging by the nose-upturning of some, an acquired taste. But I love it.

The local Philippine species, Tripneustes gratilla, produces uni of high quality, sweet with only a hint of the marine to it, and a slightly nutty finish. One of my aims here is to taste-test as many species of urchin as I can to make a sort of admittedly subjective assessment of tropical urchin flavors. I kind of pride myself in thinking that I have eaten roe of more species of urchins than just about anyone else (hey, everyone needs to be proud of something).


Tripneustes gratilla, interesting to look at, and fun to eat


Diadema savignyi, with spines that demand respect

So I laid out this plan to my newfound MSI student colleagues, saying that I was particularly interested in trying Diadema, the long-spined black urchin that is so often the bane of unwary divers who very quickly get the point of that protective spine cover. I figured that I might be among the first to try eating this formidable living pincushion. As usual for me, I’m behind in the game. Bryan tells me that Diadema is even better than Tripneustes.

I can hardly wait.


Filed under: Mooi,Philippines,Shallow Water,Uncategorized — rmooi @ 8:08 am

April 27, 2011

Getting ready

Getting organized for an expedition takes literally a year of planning. Even when you arrive there are days of checking in with collaborators, securing the final permits that allow you to do research. Part of our team spent most of the day meeting with government officials, arranging final details with our collaborators at the University of the Philippines and securing the final permits necessary. Meanwhile, the rest of the team was at the Philippine National Museum unpacking the supplies we shipped in advance with great facilitation from the U.S. Embassy. The team also met with our other collaborators and with the Director of the Museum. Elliott mentioned that we needed to find a place where we could fill our emergency oxygen tanks for scuba diving. After asking several local divers who have been on trips with us previously, we located a source. Most business is transacted via text message so we texted Nathan who was incredibly helpful and we were trying to arrange how to drop off the oxygen tanks to get filled. We got the following text from Nathan: “Hi, Terry. You can just leave the tanks at our place any time. Just look for Rasty. He sleeps in the warehouse. I will look at the tanks when I get in around 10″. We were hoping to meet Rasty but found another source right where we are going to be diving. Life here is always filled with people bending over backwards to try to help and come up with creative solutions to solving problems. Rich and Terry

Filed under: Gosliner,Mooi,Philippines,Planning,Shallow Water,Uncategorized — rmooi @ 3:24 pm

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