Bubble Nets & Torodial Air-Core Vortex Rings


Cetaceans break my heart.  They are the fragile and failing embodiment of old earth intelligence and majesty. Ever floating, flying, falling within a deep blue salty matrix of emotional complexity: empathy, loyalty, compassion, delight, elation. Further reinforcing this mystique and sensitivity last week was the Whale Museum’s revelation of the cultural breadth and character of Orca matriline song clans and formal pod greeting ceremonies.

It makes me sad. Truly. To think how singular and momentous they are and how close they have come to vanishing completely. 

So… in an effort to fend off the potential for waxing melencholic… I’m posting a blog on blowing bubbles! 

Humpback Whale Bubble Blowing
Humpback whales are efficient and practical with their bubble blowing escapades. They have a coordinated group feeding behavior that relies on mad bubble blowing skills of a single whale within their hunting party.  That one talented creature blows a curtain of bubbles around schooling fish. 


Fish fleeing from the whales below are corralled within the net of bubbles.  At just the right time to take advantage of this capture, a synchronized singsong cue urges the entire hunting party of humpbacks upward. Surfacing all together with mouths wide open, the whales are able to efficiently consume dense patches of prey.  The whales repeat this combined bubble net/surface plummet behavior over and over again, with each whale rising in exactly the same position relative to their fellow hunters.  The veritable flight pattern of a predatory fleet. Blue Angels beware!     Check out a video of this lethal bubble behaviour here: Humpback Whales Bubble Net Feeding

Bottlenose and Beluga Bubble Play
Cirque du Soleil artists–even the water-infused talents of “O” performers–haven’t got anything on the torodial air-core vortex ring juggler Tursiops truncatus or the ballistic bubble blower Delphinapterus leucas.  There doesn’t seem to be a “practical” purpose for this behavior–both learned and spontaneously invented by dolphins where this has been observed–other than sheer entertainment.   

Check out this play behavior in these two videos:  

Bubble Ring Physics
Finally, just in case you are curious about the physics of air-core vortex rings,  Marten et al. describe their formation this way in a Scientific American article:

“Any spherical bigger than about two centimeters in diameter will quickly become a ring because of the difference in water pressure above and below the bubble. Water pressure increases with depth, so the bottom of the bubble experiences a higher pressure than the top does. The pressure from below overcomes the surface tension of the sphere, punching a hole in the center to create a doughnut shape. As water rushes through the hole, a vortex forms around the bubble. Any vortex ring travels in the same direction as the flow through its center; in the case of these simple air rings, the vortex flow, in combination with the air’s natural buoyancy, propels the bubbles toward the surface.”

Learn How To Blow Your Own Air Bubble Ring Here



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Radula Action

Imagine that your teeth grew out of your tongue… and that five new rows of teeth rolled forward from the back of your mouth every 24 hours to replace the ones worn down by an instinctually compulsive licking of rocks and shells and sand. Wow… so many odd little things about human society would be radically altered if we all possessed a radula instead of our current disassociated tongue/teeth combo, don’t you think?  (Sci-fi writers take note!)

Radula1 Tonicella lineata’s radula

As the naturalist lingo of my past habitually referenced the radula as the “drill” responsible for all those tidy holes puncturing the apex of dead clam shells on Seattle’s beaches—the neat consumptive pattern left by an avaricious Moon Snail (Polinices lewisii)—my mind’s eye had always endowed radulas with a made-up morphology akin to a sandpaper corkscrew rotating from side to side. The fact, however, that the radula is actually so exotically similar (as oxymoronic as this observation might be) to our own lapping buccal appendage was therefore a bit of a conceptual adjustment.     

Radula2“Encyclopedia of nature”, Munich, 2000

Molluscs—with the exception of bivalves & aplacophorans—go around licking the world with chiton-plated tongues. Even ye olde cephalopods could potentially lick their beaks in chiton-grinding anticipation whenever a tasty morsel swims their way. And, to make it even more interesting, many of the molluscs out there also go about this feeding behavior with a noted “buccal rhythm” (see the Nobel Institute for Neurophysiology for more info on this).

Now… the sea urchins’ Aristotle’s Lantern is a pretty darn cool feeding appendage, but—at least in the anthropomorphized beat-boxing showdown between Molluscs and Echinoderms currently going on in my imagination—the radula-rhythm’d molluscs have indubitably won the “cool” award for today.   

Check out this YouTube video of “Hot Radula Action”  from this subtropical freshwater Apple Snail

P.S.   In response to Taylor’s blog post, I just wanted to share a few links I found after our lab of previously documented dissections and other virtual dissection tools.  While I believe dissection does have a very important role to play in biological training and research, I’m glad that we as a scientific and academic community are finding more and more ways to extend the utility of  each of the AWESOME organisms sacrificed so that we can better appreciate and utilize their form, function and innate biological magic to make the world a better place.

I would love to know if anyone else finds any others they think are useful!





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Your friendly local nudibranch

If you’ve been to the lab with me recently, you may have noticed my love affair with our visiting Frosted nudibranch friend*.  I know it as Geoffrey.

Geoffrey, just chillin'.

Geoffrey, just chillin'.

So, I was very excited to be given the opportunity to learn a bit more about our happy little underwater buddy for this blog, because how can you not be enthused about critters that look like underwater hedgehogs?

Frosted, White, or Alabaster nudibranchs (Dirona albolineata) are fairly common in the subtidal zone from Alaska to California.  In the San Juans, they can be found to depths of 60 meters in very high densities (up to 5 per square meter).  They can be any color from clear to greenish to peach, but always have white lining their frontal veil and cerata.  These cerata are shed for defense, like a chameleon’s tail (Geoffrey here isn’t looking too hot in this picture, probably due to all the recent handling).  This is obviously a defense mechanism to distract predators, but Dirona may also have chemical defenses.  Interestingly, as they don’t have branches of their digestive tracts in their cerata, they are unable to store nematocysts like other nudibranchs.  They don’t seem to be very well-studied little guys, and the studies that do exist mainly concern their diet and anatomy, so that’s what I’ll explore here.

Geoffreys–sorry, Dirona–eat ANYTHING: hydroids, ectoprocts, small crustaceans, sponges, barnacles, diatoms, coralline algae, detritus…anything.  However, it prefers snails, so if you’re feeling kind, feel free to give it a tasty snack.  It will crawl rapidly and randomly over the substratum, using its frontal veil as a chemoreceptor.  When it encounters a food item, it will hold the tasty morsel between its lips and ridiculously strong jaws, which will attempt to crush it.  If successful, the crushed shell is swallowed, tasty bits digested, and shell compacted and rapidly pooped out in a pile of mucus.  Here’s the kicker: Geoffreys eat up to 25% of their dry body weight per day.  That would be like an average human eating 40 pounds of food…160 quarter pounders…icky.


References: Robilliard, G.A. (1971) Predation by the nudibranch Dirona albolineata on three species of prosobranchs. Pacific Science, 25: 429-435.

*Please ignore the blatant anthropomorphising in this post.  It’s just going to happen.



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Deliciousness in Lab 3

Yum. Them sea urchins be REAL good eatin’ Uni or sea urchin is delicious gonad treat. There is nothing like some smooth gonads to make the day go by. However, not everyone likes these taste eggs or roe. Especially when it has been sitting in a tank for three weeks. We used Magnesium Chloride to kill our urchin unsuccessfully, so eating those oh, so edible ‘nads was out of the question. I decided that Thursday was not a good day to die. Well, actually it took tons of clove oil to kill our urchin. I think the clove oil would make uni taste like Christmas. In the pictures you can see that our uni was not so delicious looking.

Sea Urchin being euthanized by clove oil

Sea Urchin being euthanized by clove oil

Get your 'nads

Get your 'nads

dirty, sad uni in situ

dirty, sad uni in situ

This is what Uni should look like

This is what Uni should look like

Uni has increased in popularity and, therefore, as become a major industry. Harvesting of urchins in San Diego is harming the health of kelp forests. Interestingly, the kelp harvesting has been hurting the health of urchin population. These two industries  fight back and both causing man-supported urchin barrens and kelp forests.

Moral of the story? You should all go out and get yourself some uni. It’s delicious.



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Migratory Bivalve?? No way man.

When people think of a bivalve organism, they should typically imagine a sessile animal with it’s shell partially or fully buried in the sand and feeding through its elongated siphon which filters out plankton in the water column.

A scallop, the only migratory bivalve organism, seems to defy many stereotypical morphological features that are endemic to the class Bivalvia.

Obviously since they are not sessile, they have had no need to develop a way to anchor themselves in one spot. Infaunal bivalves such as clams, have developed a foot that elongates and helps them bury themselves in soft substratum. Similarly, epifaunal bivalves such as mussels have developed byssal threads that hold them in place. Because scallops have no need for these mechanisms, its lifestyle differs from your typical bivalve.

After watching everyone torture the poor Spiny Pink Scallops (Chlamys rubida) in the sea tables in lab 3 yesterday, I became fascinated by the way they are able to swim.

I did find a couple interesting papers about scallop swimming dynamics.


This first one is an interesting study on scallop body size and how it effects swimming trajectory in different flow speeds. They found that in higher flows smaller scallops always had a backwards net swimming trajectory in both their active swimming period and passive sinking period. Larger scallops made more progress in their active swimming period but were still at the mercy of the current in their passive sinking period. These results are fairly predictable but it’s cool to see swimming dynamics rigorously quantified.


This is a study on the effects of barnacle encrustation on scallop swimming dynamics. They found that barnacle encrustation negatively effects active swimming efficiency in both height and distance. Also they found that scallops encrusted with barnacles required more energy to swim a given distance. In the energetics studies they did, they found that there was no detectable difference in aerobic energy, but there was a difference in anaerobic energy required. Basically, they respired the same amount of oxygen, but more anaerobic nutrients were required by the barnacle encrusted scallops.

Another interesting (and relevant to our class!) thing I found in this paper is that while barnacle encrustation decreases the drag coefficient (Cd), sponge encrustation does not change it very much. So when our Chlamys rubida were frantically evading the Pychnopodia, the encrusting sponge should not have been making a very bid difference in drag.

Hoorah! Go Scallops!




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“Those things don’t move, do they?”  This is one of the most common questions I hear at the Seattle Aquarium from guests crowded around the intertidal touch tanks.  The object to their subject is invariably the humble echinoderm.  “Yes,” I inform them, “they certainly do move.”  ” But HOW?”  Ah, now we have hit upon the heart of the matter, or rather, the foot.  How DO they move?  Surely the seastar, sea urchin and cucumber are simply subject to the push and pull of the tides, going where the water flows without a care for how they get there.  Well, anyone who has ever tried to pull a Pisaster off the rocks will tell you otherwise.  They know that these creatures are not only capable of moving, but many are capable of NOT moving, clinging to surfaces with a kung-fu grip. So what is the secret to their pedal prowess?  Well, the mechanism is one which man has employed in his endeavors since ancient times.  The answer simply put, is hydraulics.

So far as we know, man invented the hydraulic pump sometime around the 3rd century BCE.  And the echinoderm?  Well, they have been employing hydraulic power since the Cambrian period, roughly 525 million years ago.  Some might say they beat us to the technological punch.  So how exactly does this unlikely water vascular system (as it’s called) actually work?  The answer will vary by species but there are relative similarities between all members of Echinodermata which are ever present…and amazing.

Cucumber Tube Feet

Cucumber Tube Feet

The basic structure of this incredible system consists of a few ‘simple’  parts.  Firstly, a madreporite (also called hydropore), which acts as a basic incurrent/excurrent and pressure regulatory portion for the water vascular system.  It functions to equalize pressure of the system with the ambient water pressure, much in the same way SCUBA equipment adjusts air pressure to match depth.  In some echinoderms (seastars & urchins) this madreporite is located on the exterior of the animal, but in the sea cucumber, this pore is internal and is able to regulate pressure via the compression of soft tissues.  Next we come to the stone canal, a short tube which leads from the madreporite to the ring canal, the hub of water distribution for the rest of the body.  Attached to this ring canal are a number of radial canal, usually numbering five, reflecting an echinoderms pentaradial symmetry.  Also attached to the ring canal you will often find polian vesicles.  These vesicles are blind sacs which hold excess water under pressure and may be utilized to add more fluid to the system if it is ever needed.  Finally, we get to the crux of the matter, the all-important tube feet!  The tube feet are fleshy stalks which may or may not have suction cup-like ends and are used to grasp, pull, hold, move and otherwise manipulate the environment and their position within that environment.  Muscular and/or elastic canals act to operate these structures, and some may be associated with bulbs and ampullae that are capable of activating tube feet by local water pressure.  An ingenious system for locomotion if ever there was one.  Amazing!

Lucky for me, most guests at the Aquarium prefer demonstrations to wordy descriptions.  So in answer to their question I will simply find the nearest seastar, and gently flip it on its ‘back’.  “Watch.”



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In the name of science..

What does this phrase mean? In some cases I think it serves as a blanket excuse for actions that would not otherwise be condoned, and in others, a legitimate cover for things that NEED to get done.  Who decides under which of these two categories “science” falls?  Sean was telling me last week about a class he took in the ethical/quick/most painless method for killing lab animals.  On one level I’m glad that they’re teaching this kind of stuff to the future scientists of the world, but on the other hand, I’m perturbed that so much of science includes using lab animals that there is a course in it.  In the case of the dissections we did on Thursday, I personally didn’t find the benefits of the dissection worth the deaths of the animals we dissected.  Sure, it was kinda cool to examine the digestive tracts of a crab under a microscope, but my background in marine biology is so limited that for the most part I had no idea what I was looking at (the guide we were provided was minimally helpful to me, no knock on it but I think it was written for people that had a basic familiarity with crabs).  Nor will I be applying this knowledge of a crabs insides to anything that I will be doing in the future.  What’s done is done, but I wouldn’t do it over again if the opportunity came up.

One thing I distinctly remember from this lab is catching the crab and preparing it for dissection.  We chose to use a net to catch him because he fought like hell to avoid capture, snapping his pincers and scuttling every which way.  It made me really sad to see that we would be dissecting something so full of life and vigor.  And then when we couldn’t anesthetize him properly, we decided to kill him by breaking him in half over the edge of the table.  I think its a little bit messed up that don’t have rules regulating the killing of invertebrates.  For my independent research project I’m doing work on some of the small farms on the island and one of them, Sweet Earth, is slaughtering turkeys and chickens in the coming weeks.  I’ve been invited to help out and I think I will if only to better understand something I’ve taken for granted up to now.  A greater appreciation for death might be the only thing I remember about this lab in 5 years, so I guess in that sense it was worth it.




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Mollusc Art – Phil

Now that Jessica has stolen my thunder by doing a great job of describing the crystalline sac and crystalline style, that fabulous organ in some mollusks that spins around in the sac, I none-the-less have to acknowledge her ability as an artist.  How she took an ordinary mussel that looked like this clam disection and turned it into this work of artclam disection-4is certainly beyond this non-artist.  Meanwhile, Brit and I were busy dissecting a clam and looking at pieces under the dissecting microscope.  And for those of you who have yet to read Jessica’s blog, the crystalline sac cut open with style inside looked like this on our specimen.clam disection-2 In the first photo above it’s the orange structure in the upper left.

Now on to a new topic (as long as Emily opened it up to non-lab entries.)

It was mentioned in class how some nudibranchs feed on Cnidarians and use their nematocysts.  Turns out that this may be important for biotechnological research.  The Cnidarian venoms are of interest because an estimated 150 million people are exposed to jellyfish stings yearly.  Preparations from nematocysts maybe useful in developing repellents to stings.  The question is how to harvest these nematocysts.

Aeolid nudibranchs have evolved over millions of years resulting in a lean mean Cnidarian eating machine.  Once eaten, the undischarged  nematocysts are divided and sent in one of two directions.  Some nematocysts go to the tips of the cerata by a process called foreign organellar retention where they serve a defensive mechanism.  The majority of the nematocysts are discharged in the nudibranchs’ feces.  Current research is developing processes to harvest the nematocysts from the nudibranch feces.  In the study, an average of 150,000 active nematocysts were excreted per day.  Using this process and using the nudibranch Spurilla neapolitana, it provided direct access to the entire range of venoms from four species of Cnidarians.  The authors concluded that their methods would help advance the research on the use of Cnidarian venoms as a source of marine natural products.

The above information was from the article Active Nematocyst Isolation Via Nudibranchs by Ami Schlesinger, et.al., Marine Biotechnology (2009),11:441-444.


Can you imagine spending your day harvesting feces from the above Spurilla neapolitana and removing the 150,000nematocysts?  Welcome to biotech research.

Enjoy that thought,




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Where have all the Gonads gone?

Question: What is worm-like in flexibility, orange and textured, and feeds off deposits on the bottom of the sea floor?

Echinodermata – Parastichopus californicus is exactly that… and more!




In our dissection of this unfortunate sea cucumber Ross and I were able to explore the surprisingly simple inner workings of the sea cucumber. And by simple I mean the few parts that make this a living organism, not that the parts themselves are simple. What seemed like forever to sedate the poor creature in both mag-chloride and clove oil we finally just had to go for it and cut into it. We started at the mouth, which we learned may not have been the best approach, but how were we to know? Shortly after cutting into the cucumber the poor Parastichopus attempted its defense mechanism and eviscerated its guts for us to see. Most sea cucumbers can regenerate the internal organs that they expel, however we had other plans for this invert and proceeded to explore its internal workings.


Cutting it open


evisceration of the guts





Our sample consisted of Buccal tentacles, Tentacular ampulla, a Calareous ring, polian vesicle, esophagus, intestine, hemal plexus, and respiratory tree, with podium covering the outside. The only thing we were missing was the Gonads. Where were they? Was the cucumber not of maturity, are they only seasonal I wondered? My knowledge of marine inverts has yet to be expanded until this point. As it turns out, Parastichopus eviscerates its gut contents between October and November every year and regenerates new ones. Spawning takes place in late summer, Parastichopus is a broadcast spawner. Sill, why no gonads in this specimen? I’ve found out through this process of gonad research that they have a closed circulatory system and hemoglobin, but no heart, water internal vascular system, and a calcite internal skeleton. They also have a 5 banded mussel wall structure that makes them part of the Echinodermata phylum like sea-stars and urchins, this is called pentaradial symmetry. They can reach up to 50 cm but typically are only around 24 cm -40 cm, are gonochoristic, and they can live up to 8 years if they are lucky enough to escape commercial harvesting. Sushi anyone? I also saw a recipe for sea cucumber chowder… yum? Apparently there is a huge market for sea cumber. I still haven’t found out about those gonads… Ah ha! The California department of fish and game has some information for me. They say that when the Parastichopus undergoes its seasonal visceral atrophy the gonads, circulatory system and respiratory tree are reabsorbed and shrink during the process of gut degeneration. They say that juveniles also undergo this process, but have not yet developed gonads. Could this be a victory? I have now 2 hypotheses as to why we didn’t see gonads in our Parastichopus, 1) it was a juvenile and hadn’t developed gonads yet (this one seemed adult due to its size though) and 2) it was undergoing seasonal visceral atrophy and the gonads were not visible to us, (yet other organs were visible).


Another species of sea cucumber


An interesting little factoid that I stumbled upon while doing research on the gonads was that sea cucumbers have dial and seasonal cycles of movement and metabolic activity. This made me think of the Nucella experiment and their tidal cycle. Correlation? We’ll have to find out!

 Thats it for now!




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Getting hot in here

Last Tuesday we went to Cattle Point to catch the low tide at 6 in the morning.  We were all a little bit groggy from the early hour but the morning chill and the variety of the organisms inhabiting the intertidal zone were more than sufficient to spring us into alertness.  Emily turned over a rock to reveal little critters scrambling to get away from the light of the flashlights (the sun had yet to rise so we were using lights).  We also discovered some mussels grouped in tight circles and, of course, the omnipresent barnacle.  The mussels were being monitored by a temperature gauge that was affixed to the rock by what looked like silly putty, but in reality acted as a layer of insulation for the button-like instruments.  They looked like the tiny circular batteries for watches and exuded the same silvery metallic sheen.  Moose explained to some of us the rationale behind gathering data from spots like this year after year after year.  Apparently mussels are subject to high environmental stress from the changing temperatures and endure varying conditions that would kill most other organisms.  Interesting fact: the mussels of the Northwest are actually subject to higher heat than the mussels of Southern California.  This is because the high tides in Socal come during mid-day, keeping the mussels wet and cool during the hottest part of the day.  The Northwest is the opposite, and the low tides during mid-day expose the mussels to high heat and drying factors during the day.  Apparently the data collected over the years is matched with mortality rates among mussels and analyzed.  Mussels are amazingly resilient creatures.  A short 3 hours outside and I was shivering in what was probably somewhere around 40 degree weather.  They routinely survive exposure to temperatures much lower.  My Northface jacket just wasn’t cutting it.  Nature has got human technology beat.  Its like the site that Ross was showing us today on bio-mimicry.  Human hubris likes to pretend that we’ve moved past nature, conquered or tamed it, but we’re still infants in the biological timescale.



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