Play Bit-o-Critter, Round 21

This one doesnt have enough detail for species level ID, but I'll take a common name or any of several suitable scientific names.  Y'know, if you think you've got the goods...

Simple questions with complex answers: why is a cooked lobster red?

Some really simple questions have surprisingly complex answers.  “Why is the sky blue?” ends up being all about differential absorbance of varying wavelengths of electromagnetic radiat… see, there, I’ve already wandered off into jargon land.

And so it is with the question “Why is a cooked lobster red, when a live lobster is not?”.  An odd question, but its exactly that kind of “I wonder why…” moment that has led to some of the greatest discoveries.  Anyway, you can argue that it is not a trivial question; indeed, the name of an entire restaurant franchise depends on the correct color change occurring when you drop a Homarus americanus into a pot of boiling Old Bay.  So what’s going on?

Well, its all about the astaxanthin, (lets call it AXT from now on).  AXT is a carotenoid, which means it’s a fat-soluble pigment that – generally speaking - is red or orange in colour.  Carotenoids give tomatoes their red (lycopene), egg yolks their yellow (lutein), carrots their orange (beta carotene), salmon their pink (canthaxanthin) and televangelists their freakish alien fake tans (but they do offset the glowing white dental veneers ever so nicely, don’t they?).  Lobsters don’t make AXT, they get it from eating their veggies like a good little lobster, because ultimately it’s a plant pigment (plants use it as a sunscreen – but that’s another post for another day!).  In its basic form, AXT is really vivid orange, almost vermilion.  But in lobster shells it doesn’t occur in its basic form; instead it’s mostly bound to a protein, called crustacyanin, which we’ll call CR for short.  AXT binds to CR in much the same way as oxygen binds to the haemoglobin in our blood, except for one big difference.  Unlike oxygen, which fits neatly in a haemoglobin molecule, AXT has to bend to fit into the CR molecule, like one of those freakshow contortionists who fold themselves up in a box.  In bending the AXT molecule to make it fit, the natural colour of astaxanthin changes – it shifts – from red to blue or blue-green.  Historically, this shift has been an interesting mystery to chemists and physicists interested in properties of pigments, because its unusual for the same pigment molecule to have both red and blue forms, as most avid flower gardeners can tell you.  On the right is a picture of the rare all-blue form of the American lobster (read more at the University of Maine website)

Enter Michele Cianci and colleagues from the University of Manchester in England.  These clever folks showed in 2002 that the colour change – technically called the bathochromic shift – is a result of the structure of the CR molecule and the way it flexes the AXT molecule like a loaded spring.  This is where the simple question yields the really complex answer.  Get a load of this phrase from their abstract:  “Recently, the innovative use of softer x-rays and xenon derivatization yielded the three dimensional structure of the A1 apoprotein subunit of CR, confirming it as a member of the lipocalin superfamily. That work provided the molecular replacement search model for a crystal form of the beta-CR holo complex, that is an A1 with A3 subunit assembly including two bound AXT molecules. We have thereby determined the structure of the A3 molecule de novo”.  Ex-squeeze me baking powder?

Yes, well, that's all well and good, but it doesn’t answer the simple question of why they go red when you cook them, does it?  Bear with me…  When next you are at the grocery store, take a look in the live lobster tank and you’ll see that they don't look like the handsome all-blue fellow above; they tend to be a mosaic of colours like orange, yellow, cream, green, blue and brown.  This patchwork arises from varying amounts of free and bound AXT in different layers of the shell, and some other factors like how thick the shell is, and whether the AXT is at the surface or in a deeper layer.  If you go ahead and buy one of these lobsters and drop it into a pot of boiling water, little happens to the AXT because it’s heat stable.  But the protein CR, on the other hand, is not.  Like most proteins, it loses its structure when you apply intense heat, unfolding like a jack-in-the-box, and flinging off the AXT in the process.  Liberated from its oppressive bathochromic bonds, the AXT reverts to its normal colour – intense orange-red.  Et puis, vous voila! – blue/green lobsters turn red when you cook them.

Much the same process happens in shrimp and crabs when you cook them too, but it was worked out for lobsters first because they only have one carotenoid – AXT – whereas other crustaceans had other carotenoids that complicated the picture even further.

PS - some genetic rarities give us all sorts of lobster colour patterns like the all-blue one shown above, but my favourite is the half-and-half.  The first time I saw one of these, I thought it was someone having a joke at my expense, but they're the real deal!  How it happens is still a mystery, but there's probably something wrong with the way they express CR on one side of the body.  Picture from National Geographic.

Tip of the Mackintosh hat to @AboutMarineLife on Twitter, for inspiration.

Cianci M, Rizkallah PJ, Olczak A, Raftery J, Chayen NE, Zagalsky PF, &; Helliwell JR (2002). The molecular basis of the coloration mechanism in lobster shell: beta-crustacyanin at 3.2-A resolution. Proceedings of the National Academy of Sciences of the United States of America, 99 (15), 9795-800 PMID: 12119396

There's a Hole in the Bottom of the Sea

With a tip of the Pirates Hat to Veggie Tales and Family Guy for the inspiration

There's a hole in the bottom of the sea,
There's a hole in the bottom of the sea,
There's a hole, there's a hole,
There's a hole in the bottom of the sea.

There's a pipe in the hole
In the bottom of the sea,
There's a pipe in the hole
In the bottom of the sea,
There's a pipe, there's a pipe,
There's a pipe in the hole
In the bottom of the sea.

There's some oil in the pipe in the hole
In the bottom of the sea,
There's some oil in the pipe in the hole
In the bottom of the sea,
There's some oil, there's some oil,
There's some oil in the pipe in the hole
In the bottom of the sea.

There's a hole in the pipe with the oil in the hole
In the bottom of the sea,
There's a hole in the pipe with the oil in the hole
In the bottom of the sea,
There's a hole, another hole,
There's a hole in the pipe with the oil in the hole
In the bottom of the sea.

There's a cone over the hole in the pipe with the oil in the hole
In the bottom of the sea,
There's a cone over the hole in the pipe with the oil in the hole
In the bottom of the sea,
There's a cone, an inverted cone,
There's a cone over the hole in the pipe with the oil in the hole
In the bottom of the sea,

There's a leak in the cone over the hole in the pipe with the oil in the hole
In the bottom of the sea,
There's a leak in the cone over the hole in the pipe with the oil in the hole
In the bottom of the sea,
There's a leak, ANOTHER leak,
There's a leak in the cone over the hole in the pipe with the oil in the hole
In the bottom of the sea,

So NOW,

There's a plume from the leak in the cone over the hole in the pipe with the oil in the hole
In the bottom of the sea,
There's a plume from the leak in the cone over the hole in the pipe with the oil in the hole
In the bottom of the sea,
There’s a plume, a killer plume
There's a plume from the leak in the cone over the hole in the pipe with the oil in the hole
In the bottom of the sea.

There's a boom on the plume from the leak in the cone over the hole in the pipe with the oil in the hole
In the bottom of the sea,
There's a boom on the plume from the leak in the cone over the hole in the pipe with the oil in the hole
In the bottom of the sea,
There’s a boom, a floating boom
There's a boom on the plume from the leak in the cone over the hole in the pipe with the oil in the hole
In the bottom of the sea.

There's a gap in the boom on the plume from the leak in the cone over the hole in the pipe with the oil in the hole
In the bottom of the sea,
There's a gap in the boom on the plume from the leak in the cone over the hole in the pipe with the oil in the hole
In the bottom of the sea,
There’s a gap, just check a map!
There's a gap in the boom on the plume from the leak in the cone over the hole in the pipe with the oil in the hole
In the bottom of the sea.

There's a bird in the gap in the boom on the plume from the leak in the cone over the hole in the pipe with the oil in the hole
In the bottom of the sea,
There's a bird in the gap in the boom on the plume from the leak in the cone over the hole in the pipe with the oil in the hole
In the bottom of the sea,
There’s a bird, a struggling bird
There's a bird in the gap in the boom on the plume from the leak in the cone over the hole in the pipe with the oil in the hole
In the bottom of the sea.

There’s a company responsible for the bird in the gap in the boom on the plume from the leak in the cone over the hole in the pipe with the oil in the hole
In the bottom of the sea,
There’s a company responsible for the bird in the gap in the boom on the plume from the leak in the cone over the hole in the pipe with the oil in the hole
In the bottom of the sea,
There’s a company, a Big Oil company
There’s a company responsible for the bird in the gap in the boom on the plume from the leak in the cone over the hole in the pipe with the oil in the hole
In the bottom of the sea.

...and we should never let up on them until they clean up the mess...

I'm baaaa-aaaaack...

Just returned from two weeks on the road, so I've got mounds of work to catch up on.  In the meantime, check out this interesting post over at Thomas' Plant Related Blog.  Its about Neutral Theory and why there are so many species distributed the way they are.  The ecology of diversity is one of my pet research areas, or at least, I like to think about it a lot (see earlier DTF posts about it here and here)

Doing my bit to help shape the next generation of fish doctors

Off to NY today to participate the AQUAVET courses, which are a collaboration between Cornell and U. Penn vet schools that aims to train veterinary students interested in fish health.  Historically, its been held at the Marine Biological Laboratory in Woods Hole, MA, but this year its in Southampton, Long Island, at the Southampton campus of Stony Brook University (shown below).  Its a terrific course: the students live in dorms for 2-4 weeks while a steady stream of faculty from all sorts of backgrounds cycle through for a couple of days each, to give lectures on their particular areas of expertise.  My part is aquarium health management principles, and how to identify parasites in histological (tissue) sections.  I am excited about the change of venue this year because the School of Marine Sciences at Stony Brook was where I was teaching before I went to work for Georgia Aquarium.  While I am out there, I'll be giving a public lecture on whale sharks; if you're in the Long Island area and are interested in the big spotty sea dogs, I'd love to see you there. 

Play Bit-o-critter, round 20

OK folks, I need a complete scientific name for this critter:

Thanks New England Aquarium!

In my post about surveying pelagic species from the air in Mexico, I mentioned schools of cownosed rays, which the locals call "chuchas" (dogs).  New England Aquarium has a perfect picture to illustrate what I mean:

 

Beautiful, aren't they?

The solution to Bit-o-Critter round 19

Juliebug correctly identified the round 19 bit-o-critter as a remora, Remora remora.  These bizarre fish use a modified first dorsal fin as a sort of sucker to hold onto other species, usually bigger things like turtles, sharks and whales.  Its actually not much of a sucker, more of a friction pad, but thats another topic for another day.  Congrats Julie!  Photo by Rene Gallo

The water is ALIVE!

Its easy to get discouraged about the plight of marine ecosystems and the future of all those incredible marine species that we love so much. This is especially so of late, with all the bad news about the oil spill in the northern Gulf of Mexico and the impacts that it may well have on several habitats. Consider this post, then, as your good news story for the week. I am here to tell you that there is still amazing stuff to see in the ocean. Incredible stuff. Stuff that will blow your mind. I can tell you this with supreme confidence, because for the last two days, that’s exactly what I have been seeing. As part of the research program at Georgia Aquarium, I am with colleagues in Quintana Roo, Mexico, studying whale sharks and other species that live in the azure waters of the Yucatan peninsula. Jeff Reid, who is the aquarium’s dive safety officer, is here and our main colleague in Mexico is Rafael de la Parra of Project Domino, who has been working on whale sharks and other marine species in the area for many years. This is a remarkable part of the world, with a lot of great terrestrial activities (can you say Cenotes, anyone? No? How about Mayan ruins?), exceeded only by the marine life, which is truly spectacular.

Yesterday Jeff and Raffa and I spent the day boating around the northeastern tip of the Yucatan along with videographer Jeronimo. Now, when you’re on a boat, you can only see a small strip of ocean either side of the vessel, and yet over the course of the day we saw lots of mobula (devil rays), turtles, flying fish, manta rays, spotted dolphins and whale sharks. We snorkeled alongside some of these animals and, in the case of whale sharks and mantas, took samples of their food for later analysis. They dine on the rich plankton soup of this tropical upwelling area, much of which consisted of fish eggs, which hints at other fish species – yet unseen – taking advantage of the plankton to start their next generation by spawning in the surface waters. Snorkeling next to a whale shark in the natural setting was a special thrill; I’ve been lucky enough to work with the animals in the collection at Georgia Aquarium since 2006, but this was my first encounter with them in the wild. Except for the slightly different “faces” (we do get to know our animals pretty well) and the parasitic copepods visible on the fins of the wild animal, it could have easily been the very same sharks Jeff and I have been working with in Atlanta.

Today, Jeff and Raffa and I joined Lilia (from the Mexican department of protected areas CONANP) and pilot Diego for an aerial survey of the waters around the northeastern tip of the Yucatan. In contrast to the boat, you can’t get in the water from a plane (its not advisable anyway), but you can see a whole lot more at once and cover a much greater area in a relatively shorter time. From the air, lots of sharks, cownosed rays, manta, dolphins, fish schools and whale sharks were all visible, and I am told that flamingos and manatees can be seen at other times too. The manta rays, which numbered in the hundreds, were especially impressive and included at least two species (see my post about taxonomy of mantas). The sheer number of cownosed rays, called chuchas in the local slang, was staggering (muchas chuchas, if you will). They formed huge schools that looked for all the world like the rafts of sargassum weed that accumulate on the wind-lines at the water’s surface offshore. Many of the turtles and mobula seemed to be in the mood for love; most turtles were in pairs (or a pair being followed by other hopeful males), whereas the mobula followed each other in lazy tandems, their wingtips breaking the surface with every stroke. Whale sharks were also there – lots of them – with their attendant flotilla of tourist boats and tiny orange specks of snorkelers in life-vests, doing their best (and largely failing) to keep up with the gentle giants.

When you have experiences such as those I have shared with my colleagues over the last two days, you are reminded why we do this stuff in the first place. Its not just for the papers, or the salary or the glory of new discovery (yeah, right!), its for those moments working with animals when you and a colleague become friends because you shared an experience of the oceans that most folks will never have. We should seek to share and recreate those moments with everyone we can, whether its in an aquarium or on the open ocean. I am pretty sure that if we could all do that, then public empathy for the plight of the oceans would skyrocket, and many of the threats that face them would be addressed quick smart.

Take a Levy walk on the wild side

I've mentioned before that this summer I’ll be part of some whale shark field work studies in Mexico. Some of it will focus on how these amazing animals find patches of their planktonic food in the ocean. There’s a pretty good likelihood that they have an incredibly sensitive sense of smell and can detect food from miles away. They’re a bit different than toothy sharks though, because they aren’t detecting “blood in the water” as such; rather, they need to be able to distinguish patches of ocean where plankton is denser from places where its less dense. How do they do that, and what chemicals are they smelling exactly? These are among the questions we will be trying to answer.

In reading up for this work, I came across the idea of Levy Walks. This is not a walk in the sense of your evening constitutional down to the Piggly Wiggly for a 6-pack and some Slim Jims. No, it really is just the name for a certain pattern of animal movement (shown at the right), one in which animals make several short “legs” of directed motion, usually in bunches, separated by longer legs with major reorientations. Its not random motion, but neither is it all that predictable, except that the pattern exists at all scales: its fractal. In other words, if we sketched the motion of an animal on paper, and drew it to scale, it would look similar if we zoomed out to the range of kilometers instead of meters and drew the pattern again. It turns out that moving by way of Levy walks increases your chances of running into patches of food, or the trails of scent they leave behind. At that point, more directed motion takes over and the animal zig zags towards the source of that delicious scent (whereupon it becomes not too different from homing in on the Slim Jims at the Piggly Wiggly after all). Sims et al. show that Levy walks are almost ubiquitous among animals that seek mobile prey; they conclude that its a sort of biological rule for finding food that has a patchy distribution.

It’s a fascinating idea; I wonder if you could apply a deliberate Levy walk pattern if you were looking for your sunglasses, trying to find Waldo, or trying to find an empty patch of beach to put your towel on. People might look at you a bit funny, but who’d have the last laugh?

Sims, D., Southall, E., Humphries, N., Hays, G., Bradshaw, C., Pitchford, J., James, A., Ahmed, M., Brierley, A., Hindell, M., Morritt, D., Musyl, M., Righton, D., Shepard, E., Wearmouth, V., Wilson, R., Witt, M., & Metcalfe, J. (2008). Scaling laws of marine predator search behaviour Nature, 451 (7182), 1098-1102 DOI: 10.1038/nature06518

Play Bit-o-critter, round 19

See if you can identify this critter, based on the bit given below.  The winner gets bragging rights and a warm inner glow.

No rest for the wicked

Returned from the Eastern Fish Health Workshop in the DC area yesterday, after our flight got canceled on Friday.  It was a fantastic meeting, for all the reasons I cited in my previous post. 

I've got one day at work today and then off to Mexico for field research with Mexican government colleagues this week (more about that later), but not for long, because teaching duties in NY on Friday and Saturday call.  While I am in NY, I'll be giving a public lecture about whale sharks at Stony Brook Southampton on the 4th at 1930hrs.  Its part of the SoMAS Spring lecture series; I'd love to see you there!

The solution to Bit-o-Critter round 18

Nobody guessed at BoC round 18 on the blog, although one colleague got it right on Friend Feed.  It was the eye and proboscis of a stromb, which is a big family of marine gastropod snails.  They are related to cone snails, but can always be distinguished by a ntoch on the margin of their shell that allows them to poke out the eyes and look around.  They have very engaging, almost comical eyes, but they probably don't see the world as we do.  The particular one I chose was a spider shell, which you often see for sale in tourist shops (and shouldn't buy, naturally)

EFHW the first day

They don't muck around at this meeting. Registration is from 5-8 on Monday, then talks from 8-11. Thankfully first night is mostly short talks and you can bring beers into the lecture hall - that's my kinda conference!

This morning has been all immunology. That's not normally my bag, but talented speakers can make the most arcane topics engaging. Steve Kaattari spoke about how antibodies can me made more or less specific through sulfide cross-linking, without changing their actual amino acid sequence. Erin Bromage also gave a great talk about how the immune systems of fish are concentrated in the kidney, and how the immune system can lose its memory of previous antigens in the face of new challenges. The upshot of all the talks is that fish immune systems are different from mammals and in many ways more complex, which may be unexpected given our usual biased view of "mammals do it BEST".

More to come...