Through The Sandglass

Zen Faulkes, sand crabs, and RocketHub

 
We don’t much think about sand as an environment, a home for critters that can be more or less welcoming, its inhabitants more or less thriving. But of course sand is home to a mind-boggling menagerie of critters on a mind-boggling range of scales; I have written, for example, about bubbler crabs, sandfish, the beast of Bali, the Southern Stargazer, and our good beach companions, the meiofauna (whom we should appreciate even more given the recent report on the hazards of building a sandcastle).

But today, it’s back to crabs, the variety of sand crab known as Lepidopa benedicti to be precise. Back in January, Zen Faulkes, otherwise known as “Dr. Zen,” a researcher at  University of Texas-Pan American, wrote a fascinating guest post here on these retiring and unheralded critters. He talked about the mysteries of colour differences amongst his sand crabs, but now his focus is on size. It seems that Lepidopa benedicti on the Atlantic coast of Florida are substantially bigger than their relatives along the Gulf Coast, and Dr. Zen wants to know why.

To help him with the fieldwork, he has this project up for (very modest) funding from the innovative “crowdfunding” initiative, RocketHub. Here’s his description from that site – which is well worth visiting to watch a video of him talking about his “Beach of the Goliath Crabs” project, and, should you wish, to make a contribution.

They say, "Everything is bigger in Texas!" But that's not always true.
Sand crabs are hipster crustaceans: you probably haven't heard of them. They live submerged in sand and leave no traces where they are that you can see from the surface.

Lepidopa benedicti live in the Gulf of Mexico, and on the Atlantic side of Florida. Museum records claim this sand crab is 50% longer in Florida than in Texas. This would be like finding a group of people who are 8-9 feet tall!
Why are Atlantic sand crabs bigger than those from the Gulf of Mexico?
One possibility is that the Atlantic environment is much better for sand crabs. If so, sand crabs might be a good species to monitor beach health.
Another possibility is that no animals move between the Atlantic and the Gulf. They might be drifting apart genetically and starting to form new species. This can be tested using DNA to see how similar the populations are genetically. Sand crabs might be a good species to study a big question in marine ecology: how do small, slow-moving animals spread from place to place?

Your donation will buy supplies (sample jars, alcohol to preserve samples, DNA sequencing supplies) pay travel for a student to come with me to gain research experience!

I am already going to Florida later this year as part of my first SciFund project (Doctor Zen and the Amazon Crayfish Civilization). Your contribution will allow me to tackle a second project on the same trip, giving me more bang for your buck!

Can we please not blow up coral reefs?

BEFORE: A Pinnate batfish swimming among other fish in Tatawa Besar in the waters of Komodo islands, Indonesia. AFTER: damaged coral reefs in the water of Tatawa Besar, Komodo islands, Indonesia. [Robert Delfs/Michael W. Ishak]

I admire corals – not only for their beauty, diversity, and the communities they harbour, but also for their fortitude. Notwithstanding our (justified) concern over the future of coral reefs today, they are extremely ancient critters and have survived for hundreds of millions of years through thick and thin. And when you consider the number of mass extinctions that have occurred in our planet’s turbulent history, those are extreme thicks and very thins.

Let’s face it, corals represent yet another example of things about which what we do know is but a fraction of what we don’t – see, for example, recent revelations on their survival skills. It’s only a few months since I had the pleasure of visiting parts of eastern Indonesia and, amongst the many memories, snorkelling around the glorious coral reefs of the Komodo Islands ranks right up there:

 
So, you can perhaps imagine my horror when recently, in the Jakarta Globe, courtesy of Associated Press, I saw the image at the head of this post and read the following story:

Fishermen Blast Premier Dive Sites Off Indonesia
Jacob Herin | April 20, 2012

Komodo Island, Indonesia. Coral gardens that were among Asia’s most spectacular, teeming with colorful sea life just a few months ago, have been transformed into desolate gray moonscapes by fishermen who use explosives or cyanide to kill or stun their prey. Dive operators and conservationists say the government is not doing enough to protect waters off the Komodo Islands in eastern Indonesia. They say enforcement declined greatly following the exit of a US-based conservation group that helped fight destructive fishing practices. Local officials disagree, pointing to dozens of arrests and several deadly gunbattles with suspects.

Michael Ishak, a scuba instructor and professional underwater photographer who has made hundreds of trips to the area, said he’s seen more illegal fishermen than ever this year. The pictures, he said, speak for themselves.
When Ishak returned last month to one of his favorite spots, Tatawa Besar, known for its colorful clouds of damselfish, basslets and hawksbill sea turtles, he found that a 200-square-meter reef had been obliterated. “At first I thought, ‘This can’t be right. I must have jumped in the wrong place,’” he said, adding he swam back and forth to make sure he hadn’t made a mistake. “But it was true. All the hard coral had just been blasted, ripped off, turned upside down. Some of it was still alive. I’ve never seen anything like it.”

The site is among several to have been hit inside Komodo National Park, a 500,000-acre reserve and U.N. World Heritage Site that spans several dusty, tan-colored volcanic islands and is most famous for its Komodo dragons — the world’s largest lizards. Its remote and hard-to-reach waters, bursting with fluorescent reds and yellows, contain staggering levels of diversity, from iridescent corals and octopuses with lime-green banded eyes to black-and-blue sea snakes.
They are supposed to be protected, but fishermen are drawn there by locally popular fish like fusiliers and high-value export species like groupers and snappers. Fishermen can be seen in small wooden boats, some using traditional nets or lines. Others have been captured on video blasting sites with “bombs” — fertilizer and kerosene mixed in beer bottles. Breathing through tubes connected to air compressors at the surface, young men plunge to the bottom and use squeeze bottles to squirt cyanide into the coral to stun and capture fish. Dive operators are increasingly seeing dead fish on the sea floor or floating on the surface.

“The biggest problem is that fishermen seem to be free to come into Komodo, completely ignoring the zoning and resource use regulations,” said Jos Pet, a fisheries scientist who has worked with numerous marine conservation groups in the area in recent years. He said they are “quite simply fishing empty this World Heritage Site.”

Sustyo Iriyono, the head of the park, said problems are being exaggerated and denied claims of lax enforcement. “It’s only part of the black campaigns against us by those who are hurt by our rules and orders,” he said without elaborating. He said rangers have arrested more than 60 fishermen over the past two years, including a group of young men captured last month after they were seen bombing waters off Banda island in the western part of the park. One of the suspects was shot and killed after the fishermen tried to escape by throwing fish bombs at the rangers, Iriyono said. Three others, including a 13-year-old, were slightly injured.

“You see?” said Iriyono. “No one can say I’m not acting firmly against those who are destroying the dive spots!”
He added that the park is one of the few places where fish bombing is monitored with any regularity in Indonesia, a Southeast Asian nation of more than 17,000 islands.

Divers, however, say enforcement has dropped dramatically since 2010, when the government reclaimed sole control of operations. For two decades before that, The Nature Conservancy, a U.S.-based nonprofit, had helped the government confront destructive fishing practices there. “No-take zones” were created, protecting spawning areas, and coastal areas also were put off limits. Patrols using park rangers, navy personnel and local police were key to enforcement.
In 2005, the government gave a 30-year permit to Putri Naga Komodo, a nonprofit joint venture company partially funded by The Nature Conservancy and the World Bank to operate tourist facilities in hopes of eventually making the park financially self-sustaining. Entrance and conservation fees — just a few dollars at the time — went up several tenfold for foreign tourists. With around 30,000 local and international visitors annually at the time, that would have given the park a budget of well over $1 million, but outraged government officials demanded that the funds go directly into the state budget. The deal collapsed in 2010, when Putri Naga Komodo’s permit was yanked. “They had no right to directly collect the entrance fees from the tourists,” said Novianto Bambang, a Forestry Ministry official.

Dive operators and underwater photographers have asked The Nature Conservancy and similar organizations like WWF Indonesia, to return to Komodo and help with conservation efforts there. Nature Conservancy representative Arwandridja Rukma did not address that possibility, saying only that the organization operates in Indonesia upon the invitation of the government.

Yes, this is horrifying: blowing up coral reefs or injecting them with cyanide is utter lunacy. But, as always, it’s not a simple issue. Unregulated and chaotic fishing have depleted natural stocks, and, regardless of what proportion of explosive mayhem is perpetrated by outsiders as opposed to locals, the fact is that the inhabitants of the Komodo islands, if not actually poverty-stricken, live very lean lives. These are some of our photos from the town of Komodo, the largest concentration of the population. These people have to live, and fishing is their main – virtually only – means of doing so. These kids deserve food, an education, a life.

After I read this piece, by yet another twist of serendipity, I received an email from Richard Bready. Richard is a frequent commenter on this blog, always adding a fascinating, and often provocative, dimension to the posts - and he is, so far, my only guest poet. It seems that, from the post on the European sand belt, he had been following a trail of links on the subject of geoconservation, and come across the site of Ashoka Changemakers – whose purpose is to create “opportunities for organizations, corporations, and individuals to drive meaningful and measurable social change.” They are supported by, amongst others, the Rockefeller Foundation and the Bill and Melinda Gates Foundation. Never having come across this initiative, I followed up, specifically, as Richard directed me, on their coastal program, and their “Geotourism Challenge 2010: Places on the Edge - Saving Coastal and Freshwater Destinations.” Now this competition has been supported by the National Geographic, the Inter-American Development Bank, and the latter’s Multilateral Investment Fund, and there is an understandable focus on Central America. But what fascinated me – and is of great relevance to the topic of this post – were two of the three winning initiatives:

1. Coral Gardens - Living Reefs

Reefs provide food and income for coastal communities and are a foundation of tourism, producing white sandy beaches and protecting shorelines. My idea has been to actively involve communities and the tourism industry in planting and caring for corals, with the dive industry trained to care for dive sites, and with resorts taking on trained "coral gardeners". Guests can also become involved and learn about reefs while they help plant corals and garden the reefs, giving something back to the destination and to the planet.

Go to the full description to read the details – this arises directly from the passion of an individual.

Then, there was this winner – deeply relevant to Komodo, and again the idea of an innovative individual:

2. Development of economic partnerships between artisanal fisher folk and tourism operators

Project will create economic partnerships/opportunities between artisanal fisher folk and the tourism sector by constructing a locally-supported fisheries co-op for certified, sustainably caught products and direct marketing strategy with local hotels/restaurants. Project will construct a marine research center that contributes to responsible tourism development/heritage protection by promoting local SMEs.

It struck me that these projects address exactly the issues that the reefs and the inhabitants of the Komodo Islands are facing – and that support for them by Ashoka Changemakers is admirable. The concept of translating these ideas into an Indonesian context is, as the article above so depressingly shows, a huge challenge. But Komodo is a National Park, and has been a World Heritage Site since 1991. If anywhere fits the definition of an “ecotourism destination,” and a prime candidate for geoconservation and biodiversity preservation, Komodo is it. But people live there and must be active participants in - and beneficiaries of - any progress. It may be difficult, but we can’t accept that it’s impossible, and surely somewhere there are people with the vision, the passion, and the expertise to make something like the initiatives described above actually work in Komodo. Please.

 

Critters versus Sand, Round 2: awesome Androctonus

 
This time, imagine that you're a scorpion, a fattail scorpion to be precise (sorry, but I never said anything about this role-playing being about cuddly and loveable, handsome or cute, but it’s often critters from the less celebrated realms of the animal kingdom that demonstrate the most remarkable skills). You are going about your desert business, scurrying across the sand in search of something to slaughter, when a sandstorm blows up. What should you do? Quickly seek shelter, bury yourself in the sand? Absolutely no need if you’re Androctonus australis, because you, unlike much of the world’s mechanised military, have developed an extraordinarily clever resistance to windblown sand. Blasting that can frost a windshield, clog up a filter, render many moving parts unmoving, never mind erode rocks, simply blows by you – sand off a scorpion’s back.

The yellow fattail scorpion (Androctonus australis) is an unpleasant creature, growing up to 10 cms in length, and capable of an envenomation that is dangerously and mortally toxic. But on their backs, they carry a bionic shield against sand abrasion, an exoskeleton that has bumps and grooves, the design of which cunningly deflects flying sand grains (illustration above, right).

All this has been recently revealed by a group of researchers at the Key Laboratory of Bionic Engineering, Jilin University, China, and published by the American Chemical Society. Erosion Resistance of Bionic Functional Surfaces Inspired from Desert Scorpions describes how these scorpions use microtextures to achieve erosion resistance, and how the researchers used Computational Fluid Dynamics to understand how these patterns work. The results have significant implications for the mechanised military (not to mention, perhaps, Toyota and Land Rover). Here’s the account from Science Daily:

Taking inspiration from the yellow fattail scorpion, which uses a bionic shield to protect itself against scratches from desert sandstorms, scientists have developed a new way to protect the moving parts of machinery from wear and tear.

A report on the research appears in ACS' journal Langmuir.

Zhiwu Han, Junqiu Zhang, Wen Li and colleagues explain that "solid particle erosion" is one of the important reasons for material damage or equipment failure. It causes millions of dollars of damage each year to helicopter rotors, rocket motor nozzles, turbine blades, pipes and other mechanical parts. The damage occurs when particles of dirt, grit and other hard material in the air, water or other fluids strike the surfaces of those parts. Filters can help remove the particles but must be replaced or cleaned, while harder, erosion-resistant materials cost more to develop and make. In an effort to develop better erosion-resistant surfaces, Han and Li's group sought the secrets of the yellow fattail scorpion for the first time. The scorpion evolved to survive the abrasive power of harsh sandstorms.

They studied the bumps and grooves on the scorpions' backs, scanning the creatures with a 3-D laser device and developing a computer program that modeled the flow of sand-laden air over the scorpions. The team used the model in computer simulations to develop actual patterned surfaces to test which patterns perform best. At the same time, the erosion tests were conducted in the simple erosion wind tunnel for groove surface bionic samples at various impact conditions. Their results showed that a series of small grooves at a 30-degree angle to the flowing gas or liquid give steel surfaces the best protection from erosion.

So just orient yourself appropriately to the wind, and scuttle off on your evil way.

 

[See also the Physorg.com report. Oh, and Richard, “envenomation” was especially for you…]

Critters versus Sand, Round 1: the fabulous fungiids

Imagine for a moment, if you will – or can – that you’re a coral. You find yourself in the lap of luxury, ensconced on a cosy bed of sand in a carefully maintained aquarium, far from the vicissitudes of life on the sea floor. And then, suddenly, this wretched scientist comes along and throws a pile of sand in, completely burying you. You’re entombed alive - what are you to do? Well, if you’re a fungiid, you simply shrug it off.

Of all the amazing things that I come across in this amazing world, the most startling are nearly always from new revelations about life on this planet. Whether it’s the constant discovery of new species, the seemingly daily expansion of the known limits for extremophiles, or simply how critters do stuff that we never realised they could, the news continues. And it is, of course, a couple of recent discoveries about how critters deal with sand problems that have caught my eye, and I will begin with a report that I just happened to see yesterday on the BBC News website, Corals inflate to escape being buried alive in sand. I have long ceased to be astounded by the frequency with which my favourite topic appears prominently in the mainstream media, but this is quite extraordinary.

For a start, if you think (like I did) of corals as static, colourful and sculptural installations on the sea floor, to be wondered at while snorkelling and protected from human depredations, then you’d be wrong. Some corals move. They may do it slowly and sedately, but they move – and the fungiidae, the so-called “mushroom corals” are the prime exponents of this skill.

So that’s a start – having been buried alive, you’re relieved to find that you’re a fungiid, capable of movement. But even so, just any old movement will hardly be sufficient to rid yourself of this burden of sand. So you flex yourself a little – and wow! You can do pulsed inflation! A few grains cascade from the pile, the burden is slightly relieved and you have even managed to get a couple of your cilia protruding above the sand. You pulse inflate again….

“Enough!” I can distinctly hear you exclaiming, dear reader, and you are quite right, enough of this anthropomorphised coral role-playing. Rather, first of all, just go to the BBC link above and watch the time-lapse animation there – it is absolutely extraordinary. It’s the work of Dr. Pim Bongaerts and his colleagues in Australia and the Netherlands, the evil scientists who buried the poor coral, and you can read - and reproduce - the authors’ personal copy of the paper here. It begins as follows:

Sedimentation represents a major stressor for scleractinian corals. Although many coral species exhibit the capacity of active sediment rejection (Stafford-Smith and Ormond 1992), only few are capable of freeing themselves after becoming completely buried. Fungiid corals appear to be an exception, as they can remove sediments through substantial polyp inflation (up to five times their normal size) in addition to mucus entanglement and ciliary action… Using time-lapse photography (speeding up time 300x), we observed that this inflation occurs in rhythmic pulses, allowing corals to completely exhume themselves after becoming covered in sand.

Ok, it’s speeded up (although really not that much) but, if you’ve already watched it, I hope that you share my astonishment. The complexity of what these apparently simple and passive critters are doing is mind-boggling - “mucus entanglement” and “ciliary action” don’t really convey what’s going on (although they are consistent with the science fiction image that comes to mind of this happening at full speed and on a large scale….).

It really is a wonderful world.

 

[The fungiid at the head of this post is Lobactis scutaria, the one below Herpolitha limax, and the images are screenshots from large movie files downloadable here.]

Sand critter guest post: the South Texas sand crab

By Zen Faulkes

South Padre Island in Texas has a world-class beach, with lovely fine-grained sand that is wonderful to walk on. The sand grains close up seem to be mostly grains of light or transparent quartz, with just the occasional bit of shell grit. At least, that’s what it looks like to my completely untrained eye.

 
I personally am not so much interested in the sand, however, as some of the creatures living in it. I have been spending the last few years digging around in the beaches there, studying a small local sand crab, Lepidopa benedicti. Because they are so little known, the species doesn’t have a common name; the entire superfamily is generally called “sand crabs” or “mole crabs.” I got started working with sand crabs for my doctoral research because I was interested in how they are able to dig so quickly and efficiently into the sand, and why they couldn’t walk like other crustaceans (Faulkes & Paul, 1997a, b).

  

For the last couple of years, I have been studying these crabs more from an ecological viewpoint. During my regular collections, I eventually made a conscious mental note of something that is incredibly obvious when you say it out loud. Some of these crabs are white, while others are almost a battleship gray.

 
When I looked in the scientific descriptions of these species, the colour of this particular species was never mentioned, and other Lepidopa species were usually described as white. Why are they different colors? We often think of colours as being important signals for animals; think of warning colours, for instance. Sand crabs spend almost all of their time buried in sand. In ten years of digging on this beach, I have seen these sand crabs above the sand twice (weirdly, on the same day!), and even then only for a couple of seconds. The crabs have small, poorly developed eyes. It seemed unlikely that they are using these different colors to signal each other.

Although the eyes of some sand crabs are small, they sometimes take note of their surroundings. Some very nice experiments with sand crabs showed how environmental factors can affect colour. For instance, mole crabs (Hippa) are found on either white coral beaches or black volcanic beaches, and they tend to match their background. What’s even cooler is that you take an animal from a white beach, and put it into black sand, and wait, it will tend to darken up after it molts (picture from Bauchau & Passelecq-Gérìn 1987; see also Wenner 1972).

This doesn't seem to explain the color differences I'm seeing in the local sand crabs, however, because they’re all being collected from one beach, which is a light tan as far as the eye can see.

Another idea that came to mind was that this was related to whether an animal was a male or female. That also turned out not to be the case, as each colour had an even split of sexes.

But two pieces of evidence suggest that these colours are not just incidental. There are more gray sand crabs than white ones. And the gray ones tend to be larger than the white ones, although there is overlap (data from Nasir & Faulkes 2010; carapace drawing by Boyko 2002).

Something that might help sort out this puzzling little question would be to look at other populations. The animals I have collected over the last few years are nowhere near the largest on record for the species. The largest individuals in this species have been found on the Atlantic coast of Florida (Boyko 2002). The average size of sand crabs there is about the size of the biggest individuals I’ve found on South Padre Island. And it makes me wonder, if the Atlantic L. benedicti are that much bigger, are they more likely to be that dark battleship gray?

References

Bauchau AG, Passelecq-Gérìn E. 1987. Morphological color changes in anomuran decapods of the genus Hippa. Indo-Malayan Zoology 4(1): 135-144.

Boyko CB. 2002. A worldwide revision of the recent and fossil sand crabs of the Albuneidae Stimpson and Blepharipodidae, new family (Crustacea, Decapoda, Anomura, Hippoidea). Bulletin of the American Museum of Natural History 272(1): 1-396. http://dx.doi.org/10.1206/0003-0090(2002)272<0001:AWROTR>2.0.CO;2

Faulkes Z, Paul DH. 1997a. Coordination between the legs and tail during digging and swimming in sand crabs. Journal of Comparative Physiology A 180(2): 161-169. http://dx.doi.org/10.1007/s003590050037

Faulkes Z, Paul DH. 1997b. Digging in sand crabs (Decapoda, Anomura, Hippoidea): interleg coordination. The Journal of Experimental Biology 200(4): 793-805. http://jeb.biologists.org/cgi/content/abstract/200/4/793

Nasir U, Faulkes Z. 2011. Color polymorphism of sand crabs, Lepidopa benedicti (Decapoda, Albuneidae). The Journal of Crustacean Biology 32(2): 240-245. http://dx.doi.org/10.1651/10-3356.1

Wenner AM. 1972. Incremental color change in an anomuran decapod Hippa pacifica Dana. Pacific Science 26: 346-353.

 

[“Doctor Zen” first got in touch with me in the spring of last year to kindly point me to some research on bubbles behaving like granular materials. I had a look at his personal web page at the University of Texas-Pan American, and discovered his research interest in decapod crustacean behaviour, in particular the unusual crayfish, Marmorkrebs; I was particularly interested in his work on crustaceans digging in sand – the slipper lobster video on his site is strangely compelling. I asked if he would contribute a guest post and he kindly agreed. I hope that readers find this as fascinating as I do – I’m reminded of some of the intriguing evolutionary questions raised by beach mice and the bleached earless lizard. Thanks, Zen, for this – well worth waiting for!].

So what on earth are these people looking at?

 
A somewhat blurry photo of a beach at night, clearly some kind of alcoholic beverage in the hands of at least two of the people, one of whom seems be in a state of some excitement, the other two staring intently at – the sand. What is the story behind this strange image?

I described a while ago the wonderful pink sand beach on Komodo Island, as we experienced it during the day. Returning at night for a beach barbecue, we would find that it had another surprise in store for us. The excited person in the photo is François, a delightful Swiss fellow traveller with whom, together with his wife, Ursula, we shared many enjoyably garbled bilingual conversations during our trip (well, garbled on our part). That evening we were loitering about enjoying the place, the wine and the company, when we heard an excited exclamation from  François who seemed to be performing some kind of bizarre dance, stomping in the sand and pointing at his feet (while, of course, cleverly maintaining the stability of his beverage). Deciding to humour him, we wandered over – to find that his stomping was producing endless flashes of brilliant blue light amongst the sand grains.

The result was a whole crazy group of people leaping around, stamping on the sand and shouting in delight – bioluminescence! Not the easiest phenomenon to photograph, but François just sent me this image, which I have adjusted slightly so that the sand grains are visible for scale:

My (not particularly well-informed) guess is that we were witnessing bioluminescent dinoflagellates, single-celled marine plankton whose name derives, dramatically and bilingually, from the Greek for “whirling” and the Latin for “whip,” reflecting aspects of their morphology. Many of them are – like the majority of marine organisms – capable of bioluminescence, mostly of this iridescent blue colour, and it was some of these critters whom the waves were bringing in that evening and providing our light show in the sand. Their individual displays were brief, only slightly more than a flash, and induced by the agitation of our pounding of the sand – apparently it is the deformation of the cell that triggers the chemical reaction. Bioluminescence is an extraordinary phenomenon, “generated by an enzyme-catalyzed chemoluminescence reaction, wherein the pigment luciferin is oxidised by the enzyme luciferase… Most marine light-emission belongs in the blue and green light spectrum, the wavelengths that can transmit through the seawater most easily.” (Sciencedaily). It seems likely that dinoflagellates use bioluminescence as a deterrent and warning mechanism, but the phenomonenon is not well understood and is the subject of extensive research - for a comprehensive resource, see http://www.lifesci.ucsb.edu/~biolum/ from the University of California, Santa Barbara. And here's a great science fair project outline on bioluminescence, with all kinds of further resources.

The illustration above is from a blog piece by Marko Manriquez, where, fascinatingly, he is proposing an art installation using bioluminescent dinoflagellates; interestingly, I found this at the same time as discovering that the Smithsonian Natural History Museum is currently holding a special exhibition inspired by bioluminescence:“The Bright Beneath: The Luminous Art of Shih Chieh Huang.” The art is inspired by our friends such as the dinoflagellates, but sadly does not feature any of the critters themselves as far as I can tell – but it makes me wish I was in Washington.

I shall end by noting that strange bioluminescent phenomena were on display in other ways that night on Komodo’s pink beach – note the dazzling effects on the head of the old guy next to François in this photograph:

 

 François, many thanks for your discovery, your dance, your photo – and your company.

Sunday sand critter: stargazing

Cute, huh? Astroscopus y-graecum, the southern stargazer (hence the astroscopus bit), is, in reality, hardly the romantic that its name implies, never mind incapable of actually perceiving any celestial objects; but is just about as nasty as it looks. It not only packs a good jolt of electricity, but is venomous to boot; however, it is extremely clever – here’s the description from the Florida Museum of Natural History:

This fish has many adaptions to life under the sand. Its pectoral fins act as shovels, allowing the fish to bury in a matter of seconds. The body is designed so that the eyes, nostrils, and most of the mouth are above the sand when the fish is under the sand. Scales are absent on head, but are present on body, extending onto fleshy area of caudal fin. The eyes are capable of protruding for a short distance, appearing stalked, so that the stargazer can see above the sand. It brings in water through its nostrils to breathe. Most fish species bring in water through their mouths. The nostrils are protected from sand grains by fleshy, comb-shaped fringes. The mouth also has these fringes around it to keep sand out while the fish is buried. The gill slit is narrow and drawn backwards and upwards into a baggy tube. This tube carries waste water away from the fish and outside the surrounding sand. This fish possesses a special talent: it is able to create electrical currents from a specialized organ located in a pouch behind the eyes. The rate of electric discharge depends upon the temperature, with a maximum of 50 volts. It is used primarily to fend off aggressive, threatening fish rather than for prey capture.

The southern, inhabiting the floors of the Western Atlantic, is but one of fifty species of stargazers that can be found all around the world’s oceans, all belonging to the family Uranoscopidae (implying a seriously long-range scoping ability). For a sense of a stargazer in action – definitely in the category of “nature red in tooth and claw” – see this video; here’s the opening scene, one of deceptive marine tranquillity – but look carefully in the sand….

[Header image from the BBC, Fabio Liverari]

 

Sunday sand: Komodo pink

No, these photos are not photoshopped – these are the real colours of this beach on Komodo Island:

 
Simply spectacular, macroscopically and microscopically, and a place to just wander, as I did – for some time. And what’s going on under the waves I described – with movies – in an earlier post.

The sand, when dry, has a light pinkish tan colour, but the dramatic hues are on display when it’s wet. The colour comes from tiny fragments of bright red coral which, when mixed with grains of quartz, shell fragments, our old friends foraminifera, and other biogenic detritus, create this glorious overall pink sand. Beachcomb a little, and there are the coarser fragments of coral, and, in the storm zone at the top of the beach, genuine chunks:

This is one of the so-called soft corals, the alcyonarians, specifically, and for obvious reasons, the “organ pipe coral,” Tubipora musica. From ARKive.org:

Unlike most corals, it is not colourful polyps that make organ pipe corals attractive, but instead, their dark red coloured skeleton. The skeleton is composed of thin tubes, or pipes, (hence its common name), which are two millimetres in diameter and cemented together by horizontal plates at intervals of several centimetres. Unless the colony has been damaged, a mass of greenish-brown or grey polyps, each with eight tentacles, obscures the skeleton. These colonies can form mounds up to 50 centimetres in diameter and may dominate large patches of reef. There are at least two species, only one of which is named; Tubipora musica. The structure of the tentacles of different colonies of T. musica varies greatly; some have broad feather-like pinnae (tiny projections) down the sides of the tentacles, whilst others have no pinnae at all.

I must have seen some of these on my snorkelling excursions, but, being no expert, failed to make the correlation with the beach; my excuse is, as the description above mentions, in the living corals the tentacles completely obscure the skeleton:

 
The organ pipe corals are much-prized, particularly for making jewellery and ornaments and by owners of salt water aquaria – for both the easily maintained living corals and for the decorative qualities of the bright red skeletons. As a result, the colonies are routinely harvested and dynamited and Tubipora musica is classified as Near Threatened (NT) on the Red List of the International Union for Conservation of Nature and listed on Appendix II of CITES, the Convention on International Trade in Endangered Species of Wild Fauna and Flora. So, a slightly sobering thought – does the dramatic debris of Komodo’s pink beaches originate entirely from natural mortality or does the activity of illegal trade make a contribution?

 

[Living coral picture credit]

Sunday sand: 150 million years agglutinating

A couple of weeks ago, Sunday sand exhibited some portraits of foraminifera (forams). I will readily admit that I find these critters entrancing, and utterly fascinating in their diversity and ingenuity. And, of course, given their ubiquity in the world’s oceans, they play leading roles as biogenic components of our planet’s sands; and recent research suggests that there are perhaps 20-50 times as many foram species as previously thought. So I was delighted when Michael Hesemann took the trouble to comment at length and point readers to the Foraminifera.eu Project. I have spent some time browsing around this great site and its beautiful images, and have hardly scratched the surface; however, I was particularly attracted to the gallery of type specimens of agglutinated foraminifera, those clever little (and not so little) critters that build their homes out of any stuff that is available – sand grains, silt grains, other critters’ shells.

I wrote a post a year ago on forams, and, in particular, the agglutinating ones, with an emphasis on the spectacular collection derived from the pioneering voyage of HMS Challenger. I have made a selection from Michael Hesemann’s site for exhibition today (including the original descriptions scales, and credits), and a number of them come from the Challenger collections at London’s Natural History Museum; most are from today’s oceans, but the collection finishes with examples from the Late Jurassic of Switzerland – forams have been agglutinating for more than 150 million years.

	Rhabdammina abyssorum M. Sars, 1869     Class: Astrorhizata  Subclass: Astrorhizana  Order: Astrorhizida  Family: Rhabdamminidae Taxon Profile; found at South China Sea  off territorial waters from 3465m depth Geological Time: recent specimen provided by Prof. Jenö Nagy Collection:  Prof. J. Nagy View of one specimen of Rhabdammina abyssorum M. Sars, 1869 detailed view with diatoms as construction material (image at the head of this post)
Hormosinelloides guttifer (Brady, 1884)     Class: Nodosariata  Subclass: Hormosinana  Order: Hormosinida  Family: Hormosininae Taxon Profile; found at Challenger Station 323   off territorial waters from 3475m depth, at 50.47 W, 35. 39 S Geological Time: recent  Images are shown with permission and thanks to Michael A. Kaminski, the Natural History Museum London (copyright-holder) and Grzybowski Foundation. The images are made with the NHM Palaeontology imaging system. HMS Challenger Collection View of one specimen of Hormosinelloides guttifer (Brady, 1884)
	Hormosina globulifera Brady, 1879     Class: Nodosariata  Subclass: Hormosinana  Order: Hormosinida  Family: Hormosininae Taxon Profile; found at Challenger Station 246   off territorial waters from 3749m depth Geological Time: recent Images are shown with permission and thanks to Michael A. Kaminski, the Natural History Museum London (copyright-holder) and Grzybowski Foundation. The images are made with the NHM Palaeontology imaging system. HMS Challenger Collection View of one specimen of Hormosina globulifera Brady, 1879
Discobotellina biperforata 1     Holotype of a specimen of Discobotellina biperforata in the Collections of the Natural History Museum, London. from Moreton Bay, Queensland, Australia, a station at 4-6 fathoms    Taxon Profile Images are shown with permission and thanks to Michael A. Kaminski, the Natural History Museum London (copyright-holder) and Grzybowski Foundation. The images are made by Andrew S. Henderson with the NHM Palaeontology imaging system. Holotype specimen of Discobotellina biperforata Collins, 1958, W.J. Parr collection at the NHM, Moreton Bay, Queensland, 4-6 fathoms, 1958.11.7.810, Scale bar = 6.34 mm
	Thuramminopsis canaliculata 1     Syntypes of Thuramminopsis canaliculata Taxon Profile: in the Collections of the Natural History Museum, London. labeled as from "Zone of A. transversarius, Upper Jurassic, Canton Aargau, Switzerland, ex Haeusler Coll." Images are shown with permission and thanks to Michael A. Kaminski the Natural History Museum London (copyright-holder) and Grzybowski Foundation. The images are made by Andrew S. Henderson with the NHM Palaeontology imaging system. Syntype specimens of Thuramminopsis canaliculata Haeusler, 1883, from Brady collection (ex Haeusler Collection). 6. ZF 5197, Scale bar = 125 µm; 7. ZF 5198, Scale bar = 125 µm

 

Thanks to Michael Hesemann and the foraminifera.eu project for these wonderful images.

Sunday sand: grains, chains, and biofilms

I guess that, if you wanted to write story for kids that illustrated the idea of the food chain, it could go something like this:

One evening, as the sun was setting over the beach, Walter the warty sea cucumber (although he preferred his grander name, Parastichopus parvimensis) was enjoying his usual dinner of sand. From in between the grains, he selected juicy, crunchy, and delicious meifoauna, delighting in the variety of flavours. But, unfortunately for Walter, among them, Nemo the nematode had just finished his dinner, and that had included some scrumptious morsels of Maribacter polysiphoniae, a very uncultured microbe. Now, Walter hated the taste of Maribacter polysiphoniae, and attempted to spit out his mouthful. But, being a warty sea cucumber, Walter couldn’t spit….

Well, perhaps there’s a good reason why I haven’t tried my hand at writing children’s stories. But I did write (unbelievably, just over two years ago) about meiofauna, the staggering diversity of miniature critters that live in the spaces between sand grains. Alarming as the idea of a zoo in your sandcastle might be, I commented how grateful we should be to the meiofauna, for they graze on bacteria and so keep our beaches clean. But what, exactly, are these bacteria? Well, at the head of this post is a portrait of a small sample on the surface of a sand grain. This extraordinary scanning electron microscope image comes from the work of Anthony D'Onofrio and his colleagues at the Antimicrobial Discovery Center of Northeastern University in Boston. This particular study has as its focus the bacterial life on intertidal sand grains from Canoe Beach in Nahant, Massachusetts, and, scrutiny at  successively higher magnifications reveals this (taken from the paper by D’Onofrio and others available online):

 
What we are looking at are incredible communities of bacteria – but these are not just any communities, since they have united together to cling to each grain as a biofilm, and biofilms are startling and mysterious forms of life. Isolated bacteria, floating around in the seawater, are referred to as planktonic, but when they alight on the surface of a grain of sand and team up, something amazing happens: the whole becomes greater than – and very different from – the sum of the parts.

Now I, for one, did not know much about biofilms until I came across these amazing images a while ago. But I should have done, since I carry them around continuously, and encounter them frequently. My quest for further understanding of these constant companions led me to the superbly informative website of the Center for Biofilm Engineering at Montana State University. Herewith, from their “Biofilm basics” section:

You may not be familiar with the term "biofilm," but you have certainly encountered biofilm on a regular basis. The plaque that forms on your teeth and causes tooth decay is one type of bacterial biofilm. The "gunk" that clogs your drains is also biofilm. If you have ever walked in a stream or river, you may have slipped on biofilm-coated rocks.

Biofilm forms when bacteria adhere to surfaces in moist environments by excreting a slimy, glue-like substance. Sites for biofilm formation include all kinds of surfaces: natural materials above and below ground, metals, plastics, medical implant materials—even plant and body tissue. Wherever you find a combination of moisture, nutrients and a surface, you are likely to find biofilm.

A biofilm community can be formed by a single bacterial species, but in nature biofilms almost always consist of rich mixtures of many species of bacteria, as well as fungi, algae, yeasts, protozoa, other microorganisms, debris and corrosion products. Over 500 bacterial species have been identified in typical dental plaque biofilms. Biofilms are held together by sugary molecular strands, collectively termed "extracellular polymeric substances" or "EPS." The cells produce EPS and are held together by these strands, allowing them to develop complex three-dimensional, resilient, attached communities. Biofilms can be as thin as a few cell layers or many inches thick, depending on environmental conditions.

And here’s their illustration of the biofilm life cycle (perhaps “bio-horror film” might be a more appropriate name – this is going on in my mouth?):

Biofilms are, quite literally, everywhere, and they present huge puzzles and mysteries. But understanding exactly what they are and how they work is vital. Efforts to combat bacteria focus on their planktonic manifestations, but biofilms are different, and are more resistant to attack than their free-floating versions. And what is more, the traditional approach to developing antibacterial weapons and strategies is to culture the critters in the lab and experiment on them. Pluck a bunch of bacteria from the environment and 99% of them will prove to be “unculturable” – they simply won’t grow in the lab. So what makes them grow in nature? This is where the work of D’Onofrio and his colleagues comes in – they are identifying the growth factors produced by culturable bacteria that trigger growth in their previously unculturable relatives. It would seem to be an extremely complex relationship in which some members of a biofilm community are intrinsically critical for the growth of others – it’s one big co-operative.

This has to be related to another extraordinary characteristic of biofilms: their DNA expression – which genes are switched on and producing proteins – is different from that of the same group of bacteria when they are separate; a biofilm is a different kind of organism in its own right. It’s no wonder that the Center for Biofilm Engineering describes how

The study of biofilms has skyrocketed in recent years due to increased awareness of the pervasiveness and impact of biofilms on natural and industrial systems, as well as human health. Biofilms cost the U.S. literally billions of dollars every year in energy losses, equipment damage, product contamination and medical infections. But biofilms also offer huge potential for bioremediating hazardous waste sites, biofiltering municipal and industrial water and wastewater, and forming biobarriers to protect soil and groundwater from contamination. The complexity of biofilm activity and behavior requires research contributions from many disciplines such as biochemistry, engineering, mathematics and microbiology. New insights into the mysteries of biofilm are being published daily in a wide variety of science and engineering journals.

But there are always two sides to every coin, and the story of bacteria and sand is no exception. The prediliction of planktonic bacteria for alighting on a grain of sand and massing themselves into a biofilm is the basis for slow sand filters. Originally developed in the UK in the nineteenth century, and influential in the eradication of cholera, these water filtration systems continue to be used for metropolitan water supplies and, in modern refinements, on a small scale in developing countries. The basic principle is simple: a biofilm forms on the surface of a bed of sand and continues to attract micro-organisms from the passing water. The biofilm or Schmutzdecke (another wonderful word) builds up significantly, removing up to 99% of the bacteria from the water – but, of course, eventually the sand must be cleaned. This technology is now very sophisticated, and so, although we have yet to understand how it all works, we should be grateful for the attraction of the surface of a grain of sand to passing bacteria.

[The extraordinary scanning electron microscope images are reproduced here under a Creative Commons Attribution 2.5 License, courtesy of the Lewis Lab at Northeastern University. Images created by Anthony D'Onofrio, William H. Fowle, Eric J. Stewart and Kim Lewis.]