Friday, December 25, 2015

Celebrating Sculpin Speciation

Merry Christmas everyone! Since you all have been good little nerds and scientists this year you get a brand new blog post in your stocking. Not only is it our first post in a while, but I'm excited to introduce you to our first ever guest writer.


Brian Harmon (Harmonus fishnerdii)

Brian is currently pursuing the glamorous world of graduate studies at the University of Nebraska. He's a sarcasm enthusiast and passionate advocate for (less than) charismatic (usually micro) fauna. So with out further ado let's get this post started!

Some fish are delicious, others put up a heck'uva fight, a few are particularly weird, aesthetically pleasing, or a critical keystone species. Then there are freshwater sculpins. These cryptic fish pretty much just sit on the bottom, doing nothing. All the time. If they don't swim they just sink, I mean c'mon, even we hydrodynamically challenged humans float. 

A sculpin taking a break from a hard day of... sitting on a different rock.

A true trophy of a sculpin is about 110mm (that's like 4 inches for those who deny the superiority of the metric system) so sculpins don't exactly attract much of a following from the fishing or environmentalist crowds. Actually they don't really have any following, except for a couple of fish nerds here and there. And yet, despite rarely being seen, they are all over North America and Europe, even in super remote and highly polluted waters.

A good day's haul of trophy sculpins.

Now that I have lowered the expectations for this month's Depth and Taxa, it's time to explain why sculpins are an amazing group of fish to study. 


The majestic sculpin. 
Courtesy and permission of Jason Ching

Sculpins present one of those philosophically challenging dinner-table appropriate conversations (especially since you don't want to eat them): what exactly is a species? Now, we drop species names all the time. Even here in this blog, scientific names get thrown around like it's no big deal. Yet it turns out the first man responsible for our modern definition and naming of species, Carl Linnaeus, had it pretty easy. When you have to start at square one, you pick the obvious animals. And it turns out telling the difference between an elephant and a rhinoceros isn't too difficult. And even this guy ran into all kinds of trouble. 


The Hamburg Hydra: one of many "species" Linnaeus debunked 
Courtesy: wikipedia Commons

So let's use a non-aquatic example most people are familiar with: lions and tigers. And a hypothesis: species cannot produce offspring with one another. Except clearly delineated species like lions and tigers can produce offspring: ligers (and the lesser known tigons). "Okay, okay, but they're sterile" you say. Well not... completely. Ever heard of the litigon? Now ligers and litigons are a bit of an odd example because tigers and lions don't meet in the wild.

"Ligers, and tigons, and pizzly bears, oh my!"
Courtesy: Wikipedia Commons

Well here is where freshwater sculpins come back into the story. Freshwater sculpins are notoriously difficult to tell apart unless you like counting fin rays and chin pores under a microscope. And if you're a sane human-being, you don't. 

No, please, you id this one.

Sculpins also don't move much. Which means isolated pockets of different species can be found within the same, rather small river system. Often these pockets overlap. Thus biologists face a challenging puzzle: how do we separate species that look nearly identical and whose ranges overlap?

Modern DNA analysis has gone a long way to solving that problem, while at the same time providing new challenges. For example, the cleverly named and ubiquitous slimy sculpin (Cottus cognatus) seems to coexist with just about every other sculpin species. However, recently biologists discovered the slimy sculpin is not one species but multiple, unidentified species. One newly identified group of previously "slimy" sculpins has been renamed the cedar sculpin (Cottus schitsuumsh). Just try pronouncing that. (Or go here to learn how). Oh and here is the kicker. They live in the same places as slimy sculpins.

A range map for slimy sculpins. Cedar sculpins are limited to western Montana,
 an area also occupied by slimy sculpins
Courtesy: The state of Montana

And they may hybridize with slimy sculpins, producing hybrids that can breed again. Further adding to this confusion is that one of the many species that coexists with slimy and cedar sculpins, the mottled sculpin (C. bairdi) is actually the Rocky Mountain sculpin (C.bondi) because the long-described mottled sculpin doesn't exist in Montana. So just how many species (and which?!) are we talking about?

So.. wait a minute. what defines a species? Well we will add one more group of fish into the mix. Rift Valley African Cichlids (sick-lids) to help explain. A single species of cichlids first colonized Lake Victoria about 10,000 years ago. Within that geologically tiny amount of time, hundreds of species... well... speciated. Many of these species are more closely related to one another than humans are to each other, and yet we are one species, while they are many. Turns out many of their behaviors and visual differences exist specifically to identify exactly who they should mate with. Side note: wouldn't that be nice? 

One of many, many, cichlid species
Courtesy: Wikipedia commons.

Humans introduced the Nile perch (Lates niloticus) into Lake Victoria for food. The introduction of a novel predator drove many of the cichlids to extinction. Many of those left began hybridizing due to changes in population numbers and environmental conditions caused by the Nile perch. Those hybrids continue to propagate, creating, you guessed it, the begins of new species.

A Nile perch. Fun fact: Linnaeus described it, and lions, and tigers. 
Courtesy: Wikipedia commons.

So I leave you with the ever-infuriating question of what exactly constitutes a species? Is it a specific level of genetic difference, producing only sterile hybrids, not producing hybrids very often? Or is the concept of a species a messy continuum that we humans have tried to neatly categorize? Though we can be fairly certain sculpins and elephants are not the same species, we can't figure out how many sculpin species we are talking about.


The closest thing I could find to an elephant-sculpin hybrid. 
Trust me, I looked far too hard.
Courtesy: Wikipedia commons.

It turns out, scientists argue about what is or is not a species all the time. Whether a population of fish is a different species often depends on whether you are a lumper or a splitter. And here's why it matters. Conserving species for the future is a challenging proposition full of trade-offs and hard choices. If we want to save species for future generations, what do we do when we aren't even really sure what the definition for species is? Think it over, and when this dilemma starts to get too hard, go id some sculpins. Maybe start here for a free guide on some more aesthetically pleasing marine sculpins!

Your first challenge.

Thanks once again to Brian Harmon for breaking the seal on guest posts here at Depth and Taxa. If you're an aspiring scientist or educator and you'd like to be featured on this blog contact our editor at patrick@nwnhc.com.

References:

Columbia Slimy Sculpin — Cottus cognatus. Montana Field Guide. Montana Natural Heritage Program and Montana Fish, Wildlife and Parks. Accessed via: http://FieldGuide.mt.gov/speciesDetail.aspx?elcode=AFC4E02080. Last accessed: 12/14/15.

Goldschmidt, T. 1996. Darwin's dreampond. The MIT Press.

USDA Forest Service, news release. Accessed via: http://www.fs.fed.us/rmrs/news/releases/content/?id=14-01-29. Last accessed: 11/15/2015.



Rocky Mountain Sculpin — Cottus bondi. Montana Field Guide. Montana Natural Heritage Program and Montana Fish, Wildlife and Parks. Accessed via: http://FieldGuide.mt.gov/speciesDetail.aspx?elcode=AFC4E02380. Last accessed: 11/15/2015

Monday, November 9, 2015

Shrimp My Ride

Yo Dawg, it's ya boy X-to-the-Z, Xzibit!


 We heard you're an emperor shrimp (Periclimenes imperator) out there who's lookin' for a new host organism, so we about to Shrimp Your Ride!


Since you're in the Periclimenes genus we know you've got about 175 relatives that have some sweet-ass hosts to chill out on. Most of your relatives love anemones and corals. In fact your genus is often called the anemone shrimps, so what you really needs is something to make you stand out. Let's get to know a little more about you emperor shrimp, and what it is that makes you big shrimpin'.

Emperor shrimp are found throughout the tropical Indian and Pacific oceans and into the Red Sea. With that kind of distribution you can't be havin' none of these sessile hosts all your relatives seem interested in. We need to get you mobile so you can meet up with the rest of your crew.

Now what makes your species cosmopolitan isn't just that you're found on reefs across a lot of the world, but more than any other shrimp, you got swag. Emperor shrimp come in a lot of colors, but whatever you're wearin' you wear it like a boss.

"Y'all don't know nothin' about the shrimp game." -Old Dirty Bivalve
Courtesy: Elias Levy & chickenvsdog via Flickr

Bright colors like that are almost always used to warn predators that an animal is toxic. But that isn't the case for an emperor shrimp, you just looks fly for the sake of it. If you're gonna be dressed that fine we're gonna need to get you a host to match.

Now don't forget, on Shrimp My Ride we usually pick our contestants from folks that are doing the right thing for their community. So how does an emperor shrimp represent? In her spare time she's out cleaning up after other animals on the reef. Emperor shrimp volunteer to pick up the trash that other animals leave behind. Mucous, old skin, detritus, and waste are all fair game for this reef janitor. All this clean up helps out the shrimp too, she eats everything we just listed. No need to bring coffee and donuts to her work parties.

Alright, now that we know our worthy shrimp a little better let's get to the reveal. How is the garage at Reef Coast Customs gonna trick out this ride?







Boom!, Check out that paint job.
Courtesy: Steve Childs via Flickr

This here is Kuni's nudibranch (Goniobranchus kuniei). It's got an electric leopard paint job, a custom gill-tuft spoiler, and that mantle rim bounces like a hydraulic suspension as it cruises along. Check it out.

Desperately needs "Still D.R.E" played over it.

Truth is we coulda gotten the emperor shrimp pretty much any sweet custom. She was the first in her genus to be found riding around on mobile organisms. She can also be found on around 28 different hosts from brown sea cucumbers and their relatives to flashy nudibranchs like this one. Emperor shrimp even ghost ride the whip on the swimming spanish dancer nudibranch.

Alright emperor shrimp, we got you a brand new ride. It's time for you to get out on the reef, and show the ecosystem.... that you officially been shrimped.

Courtesy Rickard Zerpe via Flickr

Editor's Note: Neither "Pimp My Ride", MTV, West Coast Customs, nor Xzibit have approved of this post in any way, shape, or form. That being said Depth and Taxa would like to say thanks to each of those entities for bringing an awesome show with so much potential for parody into the world. We heard that artists like to be thanked for their works, so we put a thank you into our thank you, so we can thank you while we're thanking you.

References:

Fransen, Charles, & Hoeksema, Bert, "Going for the Stars: Extending the Host Record for the Reef Dwelling Emperor Shrimp, Periclimenes imperator (Pontoniinae), Marine Biodiversity (2014) 44:465-466.

Shoup, John, "Notes on the Behavior of Periclimenes imperator Bruce, An Ectocomensal on the Dorid Nudibranch Hexabranchus marginatus Quoy and Gaimard (Decapoda, Palaemonidae)", Crustaceana,  Vol. 23 No. 1 (Jul., 1972), pg. 109-111.
Accessed via: http://www.jstor.org/stable/20101910?seq=1#page_scan_tab_contents

"Chromodoris kuniei", The Sea Slug Forum.
Accessed via: http://www.seaslugforum.net/showall/chrokuni

Friday, September 11, 2015

Gene You're Positively Glowing!

Out on the beaches of the Pacific is a group of heroes. A squad of jiggly life savers, spending their days scanning the surf, waiting for their moment to pull you back from oblivion... 


What!? Oh God...NO. Get your head out of the gutter, uck! What the heck is wrong with you? I'm talking about jellyfish; specifically the water jelly (Aequorea victoria), they're also called crystal jellies and have many other common names, so for this post we'll just call them Aequorea (pronounced: ay-core-ee-uh). 

Just as much acting talent in this photo, as in the one above it.
Courtesy: Denise Allen via Flickr

Now we've often declared our love for jellies. In fact this isn't the first time they've appeared on Depth and Taxa. If you want to get a refresher on the jelly life cycle, and learn about one of Aequorea's cousins check out the older post here. But Aequorea are especially interesting thanks to their contributions to the field of medicine. You might be picturing some kind of Doogie Howser scenario with a jelly subbing in for Neil Patrick Harris, and you'd be right to want to watch that. But what Aequorea have provided for humanity goes beyond just caring for sick individuals, and making us laugh Tuesdays at eight on ABC.

At first glance Aequorea only possess a simple elegance. They're completely clear, and don't have particularly flashy innards like some species. The wagon wheel-like structure inside their umbrellas is a system of canals that distribute nutrients around the jellies' bodies. But radial canals are a basic part of jelly structure, so although they're pretty, they aren't particularly distinctive. To see what has made Aequorea so important to humanity we need to take the lights down.

Oh man, those damn ravers keep leaving their trash everywhere...
Courtesy: William Ward via The Encyclopedia of Life

That ring is the outline of the bell margin of an Aequorea jelly. The glow you see is naturally produced by the jelly itself. Interestingly, we don't know for sure why these jellies produce this light. They don't constantly flash like fireflies, nor do they glow continuously like the stage at a Deadmau5 show. For the most part we've only observed Aequorea glow after they've been jostled by a human. Even if we don't understand why Aequorea glow, scientists have spent a lot of time figuring out how they do it.

In the 1960's, while trying to isolate the glowing material from Aequorea jellies, Dr. Osamu Shimomura and his team determined that a pair of proteins is actually responsible for producing this jelly's light. The first in this dynamic duo is a molecule called aequorin. Aequorin emits blue light when it's exposed to calcium ions. The second protein, which produces that green fluorescent glow we see is called... green fluorescent protein. Points for clarity I guess. Green fluorescent protein, or GFP, only glows when exposed to light in the same spectrum as the light produced by aequorin. So first, calcium ions flow into the aequorin which flashes blue, then the blue light hits the GFP which absorbs it, and then the GFP releases some of the energy it absorbed as green light.

Okay so how is glowing protein helpful to medicine? Well it's what triggers the glow in these proteins that's important. See calcium is an important trigger in both the nervous and muscular system. Calcium ions flowing into nerves spark them to send out the chemicals that transmit information between themselves and the next nerve in the chain. Scientists can inject aequorin into the area around a nerve and figure out where and when the calcium is flowing to the cell by seeing when the aequorin glows! This is incredibly useful when studying nervous systems because you can actually observe a nerve functioning, which is normally an invisible process.

Aequorin being activated by a calcium solution.

So aequorin is pretty cool, but it's green fluorescent protein that has really changed the landscape of cell research. GFP normally absorbs the light from aequorin to glow, but will also absorb light from the nearby UV spectrum. So that same black-light you used to make that Bob Marley poster look so cool in your dorm can be used to peer into the chemicals that sustain life itself.

Scientists managed to clone the green fluorescent protein and ever since have been attaching it to other proteins to watch how they're made, where they go, and how long they last inside the bodies of different animals. Dozens of fluorescent proteins, in several colors, have been created from GFP and others have been found in animals like sea anemones. Mice have been genetically modified with GFP tagged normal cells and glowing red protein tagged cancer cells. When observed under black-light scientists can actually watch how the cancer cells grow and spread in real time without harming the mice.

The thing that makes GFP so powerful is that it can be added to almost any cell or protein. So if you have a question about how fetuses develop, tag an egg cell with GFP and watch it divide. If you want to watch nerves grow as a mouse learns, tag their brains with GFP, and see them think. If you want to release a bunch of infertile male mosquitoes into a population to eliminate malaria without pesticides. Tag their testicles with GFP so you can sort the boys from the girls, and get to sterilizing. All of these things have actually been done using modern genetic techniques and a variety of fluorescent proteins.

These are the nerve cells in a mouse's brain expressing different chemical signals.
You're observing this animal's brain tell its body how to function
Courtesy: ZEISS Microscopy via Flickr 

Okay so maybe it isn't Aequorea itself that'll save your life. Mostly they'll keep eating plankton and washing up on shore like they've been doing for millions of years. But if it weren't for Aequorea's development of GFP we would probably never have been able to discover all that we have about living things, especially our own bodies. Animals and plants shouldn't be protected and preserved solely for their potential usefulness, but if one of the least noteworthy jellies can single tentacledly spark an entire research industry; imagine what else we can learn from the "nobodies" on the tree of life.

References:

Nikon's Microscopy U,
Accessed via: http://www.microscopyu.com/articles/livecellimaging/fpintro.html

The GFP Site; From professor Marc Zimmer at Connecticut College.
Accessed via: http://www.conncoll.edu/ccacad/zimmer/GFP-ww/GFP-1.htm

Mills, C.E. 1999-present. Bioluminescence of Aequorea, a hydromedusa. Electronic internet document available at http://faculty.washington.edu/cemills/Aequorea.html. Published by the author, web page established June 1999, last updated January 11th 2009

Shimomura, O., "The Discovery of Aerquorin and Green Fluorescent Protein", Journal of Microscopy, Vol. 217 Pt. 1, Jan. 2005, pg. 3-15.


Thursday, July 9, 2015

Naut Again

Oh wow, there's some wonderful news that's come out of the US East coast recently that hasn't gotten the coverage it deser....

"NAUT SO FAST PUNK!"
Courtesy: DarTar via Wikimedia Commmons

Oh, god no, not this again. How many weeks am I going to have to go without getting interrupted by a cephalopod? What do you want chambered nautilus (Nautilus pompilius), and did you seriously just use your own name as a pun?

"I'll use my name however I want after you and that wannabe 
Greek hero besmirched it. She should be proud to be 
associated with us nautiluses."
Courtesy: Michael Bentley via Flickr

Alright, alright, I didn't mean to offend anyone. I wrote about argonauts last week since they're a cool family in their own right. I guess I didn't think about how little people know about your family too. Tell you what, I'll make this post all about you, if you promise to tell the other cephs to stop interrupting me. I don't want a ram's horn squid butting in next week.

"Alright deal, but I'm gonna stand here and make sure you do us justice"
Courtesy: OCVA via Flickr

Okay well, if we're gonna give this family the credit it deserves we need to talk about world domination. Don't worry, you needn't imagine a future where shelled overlords subjugate earth's other species, because it already happened. Nautiluses are old, very old, in fact their family members are the OG cephalopods. The first nautiluses to appear had straight shells, but around 400 million years ago they developed the familiar spiral we see today. They were so successful that they, and their cousins the ammonites, would go on to dominate the seas for eons. Nautilus even survived the worst extinction of all time which killed 96% of all life in the sea. Not too shabby for an animal that's essentially a fancy snail.

Even though they ruled the oceans for so long, the nautiluses eventually gave up their family's dynasty to live a life of quiet retirement. Today only two genera of nautilus exist, down from the 75 or so at their peak. Modern nautiluses are found only in the Indian and Pacific oceans in the deep waters at the steep edges of coral reefs. Yet they are some of the most fascinating organisms to occupy those spaces.

Of course what stands out most about nautilus is their incredible shells. Nautilus are the only cephalopod left to still have an exterior shell, which means they don't need all the gaudy color and texture changing flashiness of their cousins. Instead of hiding, speeding away, or out-thinking their predators nautilus prefer the simple life scavenging food off the bottom; and cruising through deeper water at times when predators are at rest.

They're kind of like that friend from college who moves to
 Idaho and starts a goat farm because "It's just easier."
Courtesy: Hans Hillewaert via Wikimedia Commons



Now you might notice that the nautilus' shell is pretty burly. There are hardly any animals with shells that thick that even bother swimming. Other heavily shelled mollusks like clams and snails spend most of their time on or in the ground. So what does the nautilus do that makes it able to hover up in the water like that? Are they just incredibly strong? Not really. When you watch a nautilus puff along by forcing water through its siphon, it kind of makes you want to hand it an inhaler and tell it to go sit on the bleachers. So if it's not pure herculean strength that keeps the nautilus afloat what is it? Well my friends, the nautilus succeeds thanks to the magic of good engineering.

I think like a third of our readers just found their spirit animal
Courtesy: Jason Westley Upton via Flickr

Inside the shell are the structures that put the "chambered" in chambered nautilus. The largest chamber is where the nautilus' mantle is housed, but the others are empty of everything except air and a little bit of water. When a new chamber forms the nautilus walls its previous space off and amazingly, drains the water. See if the chambers stayed filled then the nautilus would get dragged to the bottom thanks to the weight of the water inside the shell. Emptying water from the chambers has the same effect as if the nautilus were to tie balloons to its shell. The air inside pushes up towards the surface while the weight of the shell pulls down, and the two forces balance one another out to make the nautilus neither sink nor float.

You might be wondering: If the nautilus seals the chambers how does it get the water out? Well running through the chambers is a really cool organ with a really cool name, a siphuncle (pronounced: sigh-fun-kull). The siphuncle is a tube that uses water's own physical properties to fill and empty the chambers. See water has a tendency to try and balance the concentrations of different minerals dissolved in itself. So if you put a screen that will only let water through between two solutions and you make one much saltier than the other; the water will cross the screen to the salty side until the two sides' ratios of salt to water are equal. This is exactly what the siphuncle does. When the nautilus wants to remove water from the chambers it adds salt ions to the outer layer of the siphuncle and the water just seeps on out of the chamber. When the nautilus wants to add water to the chambers it does the opposite. This system requires basically no energy on the animal's part, so it's a great strategy for staying properly buoyant.

Who says functional machines can't be pretty? Those little struts in the center 
of each chamber hold the siphuncle in place as it runs through the shell.
Courtesy: Jitze Couperus via Flickr

Of course everyone focuses on the shell of the nautilus, so much so that these animals are being impacted by fisher people catching them for their shells. Many scientists and citizens who care a lot about nautilus are doing everything they can to show the international community that nautilus, not only deserve, but need our protection. The easiest way to do your part is to never buy new nautilus shells. Instead look around antique stores, or purchase nautilus fossils, which have the benefit of being infused with beautiful minerals from fossilization.

Aside from their shells, nautilus are also impressive thanks to over 90 tentacles! These tentacles are much simpler than the complex arms of the nautilus' cousins. They have no suckers and instead use a series of grooves to grip surfaces. They're also incredibly sensitive to scent/taste. As a scavenger nautiluses need to be very aware of where food is sitting, and all of those tentacles act like an array of antennas picking up the fishy signal of food rotting on the bottom.

Okay nautilus, was that a satisfying amount of information for you? We can always come back another week and learn more.

"Well that was better than naut. It'll do for now, and naut to worry,
you've naut seen the last of me."
Courtesy: David Remsen via Flickr

Ugh, the puns man, the puns...

References:

Dunstan, A., Ward, P., & Marshall, N., "Vertical Distribution and Migration Patterns of Nautilus pompilius", PLoS ONE 6(2): 16311, Feb. 2011.
Accessed via: http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0016311

Ward, Peter, "Cameral Liquid in Nautilus and Ammonites", Paleobiology, 5(1), 1979, pg. 40-49.
Accessed via: http://www.jstor.org.ezproxy.library.wwu.edu/stable/2400389?seq=1#page_scan_tab_contents

Crook, R., & Basil, J., "A Biphasic Memory Curve in the Chambered Nautilus, Nautilus pompilius L. (Cephalopoda: Nautiloidea)", Journal of Experimental Biology, June 15th 2008.
Accessed via: http://jeb.biologists.org/content/211/12/1992.long

Dunstan et al., "Nautilus pompilius Life History and Demographics at the Osprey Reef Seamount, Coral Sea, Australia" PLoS ONE, 6(2): e16312, Feb. 2011.
Accessed via: http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0016312

Friday, June 26, 2015

Precious Argo

How's the old saying go? "If it looks like a duck, swims like a duck, and quacks like a duck, then it's probably a duck."

"Quack?"
Courtesy: Derek Bruff via Flickr

By extension I can imagine this test applies to any animal. Let's pick a random one and try it, shall we? If it looks like a..... Nautilus, swims like a nautilus, and has a shell like a nautilus it must be a nautilus. 

"Oh my God! What did you just call me!?"
Courtesy: Michael Vecchione via TOLWeb.org

Oh yeah I'm sorry, paper nauti..... I mean greater argonaut (Argonauta argo). I totally forgot about you. How about I make the rest of this post about how awesome you, and the other three species in your family, are to make up for it?

"We can live with that. I'll just sit here and make sure you
 don't mess up again"
Courtesy: NOAA Photo Library via Flickr

Okay where to start? Well, how about at the very beginning like my nanny used to say. Disclaimer: My nanny may have just been Julie Andrews movies. Anyway, we've known about argonauts for an incredibly long time. Their delicate, paper-thin, shells have been found painted on artifacts from 4000 years ago! Of course, back then we barely knew anything about these animals because we were mostly finding their old shells washed up on the beach. 

However many of the ancient Greeks were talented naturalists, and they started looking closer at these coiled beauties. Aristotle noticed that the argonauts could climb out of their shells because they aren't attached to them like a true nautilus or any other shelled mollusk. So how did Aristotle think argonauts got their shell? Well he assumed they stole it. For the longest time scientists thought that argonauts couldn't be making their own shells, so they were taking them from an unknown animal and using them as boats. Now this seems a little crazy, but add in the fact that female argonauts have sail-like webs on two of their arms, and you have the perfect animal to send after the golden fleece

Hahaha...What is it even...? Hahaha...There's a boat to compare it to..Hahahaha!
Bless you for this: Gerard Van der Leun, via Flickr

Although the theory that argonauts combined Grand Theft Auto and that pirate Assassin's Creed (Hold on I have to go pitch an idea to Microsoft) persisted well into the 1800's, eventually science started to sober up. We later discovered that female argonauts make the shells using glands in their webs that secret calcite. They spread these webs out over the shell and lay down material bit-by-bit like nature's 3D printer. 

 On the left you can see the webs with chromatophores, extended over the shell.
On the right this female has pulled the webs back, exposing her construction.
Courtesy: Michael Vecchione via TOLWeb.org

 If you're an astute reader, you've probably noticed that I've only mentioned female argonauts so far. This follows the history of these animals because for the longest time we had no idea what the males looked like. Why? You might ask, well they're tiny, like really tiny, only 1% the size of a female, and the biggest species' female only gets to 30cm across. Plus the males don't build shells, oh and sometimes they only have seven arms.

See argonauts are octopuses, and they normally have eight arms like any of their relatives. However one of a male octopuses arms is very different from the others. The third arm on his right side is called a hectocotylus (pronounced: heck-toe-cot-oh-luss) and it's used for reproduction. The males of most bottom-dwelling octopuses insert their hectocotylus into the female's gill opening; and sit there for a bit while a packet of sperm passes from inside his body, down the arm, and into the female's oviduct. Argonauts don't have the luxury of that kind of time though. They differ from their cousins by living up in the water column, instead of down on the sand. Living in the open ocean is great way of avoiding competition with your cousins down below, but it also means you have to travel far and quick to find food, mates, and shelter. 

Because the ocean is so big, and argonauts so small, males may not have many chances to find a female. To make sure they mate effectively the male argonaut's hectocotylus actually breaks off inside the female's body cavity, and he swims away. By embedding his sperm delivery system in the female, the male has insured that it's his DNA that fertilizes the eggs. Plus it's a great way to screw with naturalists. This is not a joke, the scientist who first found a hectocotylus buried in a female argonaut thought it was a parasitic worm!

 Plus what the hell do we call this thing, a septopus?
The eighth arm is kept inside that pouch.
Courtesy: Edwald Rubsamen via Wikimedia Commons and Public Domain

Now here's where the functional beauty of the female's shell can accompany its aesthetic beauty. Since she lives up in the water there's very little to attach her eggs to, and good material could be floating hundreds of miles from the female argonaut, so she lays her eggs right inside the shell. Female argonauts handcraft baby strollers to push their kids around in until they hatch. Not only that, but the shape of the shell allows the female to trap air in its top which helps counter-act the weight of her body and the eggs; and keeps her from rising or sinking too fast. 

You can see the eggs hanging out of the lower part of this female's shell.
She's new to this whole arts and crafts thing.
Courtesy: Bernd Hoffman via Wikimedia Commons

So how'd I do argonaut? Did we cover everything that makes you so cool? Be fair, we don't know much about you since you're all so small and you live in oceans around the entire world.

Whoooo! Nice work! Go team Argo! High eights all around!
Courtesy A.E Verrill via Wikimedia Commons and Public Domain

References:

Finn, Julian K., "Taxonomy and Biology of the Argonauts (Cephalopoda: Argonautidae) with Particular Reference to Australian Material", Molluscan Research, 2013, Vol. 33, No. 3, 143-222.

Heeger, T., Piatowski U., & Moller, H., "Predation on Jellyfish by the Cephalopod Argonauta argo", Marine ecology Progress Series, Vol. 88, 293-296, 1992.

Orenstein, Marcie, "Marine Invertebrates of Bermuda: Paper Nautilus (Argonauta argo)", The Cephalopod Page

Mangold, K., Vecchione, M., & Young, R., "Argonautidae", Tree of Life Project

Wednesday, June 17, 2015

Internet Explorer

Oh man I'm so excited I can't contain myself!



No I haven't slipped forward in time to the holiday season, and posted this from the future (Obviously what you were thinking). It's still the start of summer where I am and I'm loving it. Not only has the sun started staying up late again, but it's the middle of the field research season here in the northern hemisphere!

See ocean conditions can be tricky; just ask anyone who's been out in a small boat on a really windy day. In order to take ships out, and actually accomplish anything, it's nice to avoid the season where the waves can average ten feet high. The cables that attach submersibles to ships generally don't like being whipped around that much. Plus even ocean researchers get seasick sometimes. About this time every year research vessels from across the States, and around the world gear up for their big research trips that will run throughout the summer.

Alright that's nice for everyone who works in those fields, but why should everyone else care? Because this is the time when all the cool footage and crazy stories from the deep start to come out, that's why. Thanks to this newfangled "internet" that seems to be sticking around, we have the opportunity to watch many of these events live as they happen. Remotely operated vehicles (ROV's) around the world are shooting footage from hundreds, even thousands, of meters below the ocean. And already incredible events are unfolding before the eyes of anyone with access to the web.


That video shows the largest of the toothed whales, the sperm whale (Physeter macrocephalus), casually inspecting a highly advanced underwater robot. If the embedded video didn't work click here to see it on youtube. This incredible event happened during one of the ship E/V Nautilus' research dives into the Gulf of Mexico. The crew of the Nautilus broadcasts their entire expedition season live from their website while they're at sea. t any moment you can be watching, not only the crazy cool creatures you almost always find in the deep, but also one in a billion chances like this. 

In addition to streaming the entire expedition, and allowing you to listen to scientists being the adorably huge dorks they sometimes are, the Nautilus also allows you to ask questions of the crew in real time. It's an amazing chance to learn right from the researchers while they're doing the research. And the research they're doing is incredible.

So far this season the expedition has been focused on the Gulf of Mexico where oil and gas naturally seep out of the sea bed. This petroleum rich region was the site of the BP Deepwater Horizon oil spill which is in the midst of its five year anniversary. The Nautilus even visited the well head, and posted a sobering, silent, ten minute video of their survey of the area. The video is a stark juxtaposition to the live footage of crude billowing out of the well from 2010. This catastrophe has been the catalyst for a big scientific push to find out exactly how spills, and the methods used to clean them up, affect deep sea environments. Oil is a normal part of the Gulf ecosystem, but the blowout blasted more material than would have been released over decades, in a matter of months. 

It's like the Old Country Buffet for oil consuming bacteria.
There's way too much food and most of it ends up on the floor.
Courtesy: Lumis via Flickr

I think we'll be revisiting the spill in more detail here in a future post, so we can stay up-to-date on our understanding of those events. For now though, let's turn back to giving you cool research programs happening right now.

Aside from the E/V Nautilus the other crown jewel in the ocean exploration outreach world is the R/V Okeanos Explorer. While Nautilus is part of a non-profit organization founded by Robert Ballard (the guy who found the titanic, and helped discover hydrothermal vent ecosystems) Okeanos Explorer is owned entirely by the citizens of the United States. In fact, it's the only ship in the US fleet devoted solely to "explore our largely unknown ocean for the purpose of discovery and advancement of knowledge." (Okeanos Explorer webpage). 

"Yeah I own a boat, it's not a big deal or anything."

Both ships are devoted to opening up ocean research to the public and increasing the visibility of the world's greatest frontier. It's become an old cliche to say that we know more about the surface of the moon than the bottom of the ocean, but it's still true. In 2000 former president Clinton brought together a panel on ocean exploration that challenged researchers to dedicate energy to exploring parts of the ocean not usually covered by other research vessels. The Okeanos Explorer and the Nautilus are the answers to that challenge. In the 15 years since the panel's report both ships have sailed all over the world. They've found new species in unique ecosystems, peered into the chemistry of the deep ocean, and discovered historic and modern archaeological treasures. All the while their satellite link-ups and devotion to education have provided everyone with a chance to find wonder right alongside the scientists at sea.

So what are you waiting for? Get your infinitely curious, ocean loving self over to nautiluslive.org, or  oceanexplorer.noaa.gov/okeanos/ and see what's happening for yourself. Okeanos also has a great Flickr feed all free for you to peruse and use whenever you like. If you see something cool share it on social media, tell your friends, use it in your classes, and always keep exploring!

References:

"About NOAA Ship Okeanos Explorer", January 5th 2015, NOAA Ocean Explorer Website, http://oceanexplorer.noaa.gov/okeanos/

The Ocean Exploration Trust, http://www.oceanexplorationtrust.org/

"New Frontiers in Ocean Exploration: The E/V Nautilus and NOAA Ship Okeanos Explorer 2011 Field Season", Oceanography, Vol. 25, No. 1, Supplement, March 2012, Accessed via: http://www.tos.org/oceanography/archive/25-1_supplement.pdf

Nautilus Live, http://nautiluslive.org/

Sunday, May 10, 2015

Maternal Instincts

Hi ho everyone! I know it's been forever since I last posted, and you're probably missing your weekly-ish fix of fascinating marine science and news. I've been enjoying an incredible field course through my university that has been eating up all my time. I might do a post about it at some point because we've spent some time doing ocean education. Anyway Depth and Taxa is back just in time for mother's day, so this week we'll be looking at some of the best moms the ocean has to offer.

All moms are willing to give up everything for their kids, but our first ocean mother takes this to a bit of a literal extreme. We've talked about how giant Pacific octopus (Enteroctopus dolfleini) are the largest in the world before, but there's a lot more to these incredible creatures than their size. After mating with one or more partners, female giant Pacific octopus lope off to find themselves a den. Sturdy shelters are an important part of octopuses' entire lives since they have no shell to protect them like other mollusks, but this will be a special space. The den the mother to be is looking for will be her nursery. Once she's found the perfect spot, she'll start braiding together 80-100 thousand eggs with her bare suckers. 

  "Oh you knitted those socks yourself? That's cute."
Couretsy: Ratha Grimes via Flickr

The mother octopus sticks these ropes of eggs to the ceiling where they'll spend the next five to seven months developing. In all that time mom never leaves the den. She sits in her nest, brushing her arms over the eggs to keep them clean, and pushing water from her siphon over them to keep them oxygenated. From the day she lays to the day the babies hatch she never eats a thing. All that devotion and starvation takes a severe toll on mother octopuses' and usually their last act is to push their adorable octolings out into the world with a blast water. 

It's certainly a beautiful story of motherly commitment, but why does it have to be so sad? Why can't mom stick around and raise her young. Well no one knows for sure, but it might have something to do with the fact that adult octopus compete to the point of occasionally eating one another.

 "One look at you and I can't disguise. I've got hungry eyes."
Courtesy: John Turnbull via Flickr

To find an ocean mom that keeps mothering long after her kids are capable of surviving on their own; we need to return to the more familiar world of mammals. 

Orcas, also called killer whales (Orcinus orca), are found across more of the world than most other mammals. In order to become so successful they've had to come up with some incredible strategies for survival. One of those strategies is recognizing that "mother knows best". Orca groups, called pods, are led by matriarchs who care for their children their entire lives. These mother-leaders remember where the best hunting grounds are, what areas to avoid, and where to go when food is scarce. Keep in mind that orcas can live as long as humans. A whale named Granny from the Salish Sea in the Northeast Pacific, is estimated to be 103 years old, far, far beyond reproductive age. A theory called the "grandmother hypothesis" suggests that the life experience of these mature females is so important that, evolutionarily, they contribute to the reproductive success of their pod even after they go stop reproducing. Of all the animals in the world only humans, pilot whales, and orcas are known to go through menopause, and their wonderful mothering may be why.

Courtesy: Mike Charest via Flickr

So who else is left? What other mother can compete with these two incredible species? Well the answer is simple, mine. My mom has been a big part of my life for as long as I've had it, and I want to dedicate this post to her this mother's day. Mom has always respected my goals and encouraged me to pursue the sea since I first responded "oceanographer!" when I was asked what I wanted to be when I grew up. 

The only thing that's changed in 21 years is that my brother 
doesn't fit in a dolphin anymore.

Mom and I always have wonderfully deep conversations about education and science, and she's been the number one supporter for the blog. I know that, like a giant Pacific octopus, my mom would give up everything to give her family a head start on life. But she'll also be around for years to come, to give me and my brother guidance, just like an orca matriarch. So since I know she's reading this, I just want to say thank you, thank you for everything, and Happy Mother's Day.

References:

No author, "Orcas of the Salish Sea, Part 1 & 2", The Orca Network. 

Weiler, Nicholas, "Menopausal Killer Whales are Family Leaders", Science News, March 5th 2015. 

Anderson, Roland C., Mather, Jennifer A., & Wood, James B., "Octopus: The Ocean's Intelligent Invertebrate",  Timber Press, May 21st 2010.





Friday, April 10, 2015

A Sea Lion Story

By now it's probably come across your computer screen at least once. The story may have even shown up in your physical paper. More than 1,800 California sea lion (Zalophus californianus) pups have shown up emaciated on the beaches of California since January. Unusual mortality events like this are most troubling to us because it's adorable baby animals that are suffering, so it's a good opportunity to draw awareness to ecosystem scale issues.

D'aww who's a good vector for a better understanding
 of ecology!? You are, yes you are!
Courtesy: Jaina via Flickr

So what do baby sea lions have to do with the ecosystem as a whole? Well ecosystems are all the living and non-living things in an area that interact with one another. This means that every piece in an ecosystem is significant to the others in some way. For example small fish are important to large predators, currents are important to plankton, and temperature is important to everyone. Each piece has direct effects on the others and those effects themselves interact.

On the surface (pun intended) starving sea lion pups seems to have a pretty straightforward cause. You would assume it's because there isn't enough of whatever it is sea lions eat. That's part of the story, but there's more to it. When baby seals and sea lions are first born they lack the thick blubber of their parents. Pups have to drink extremely rich milk to bulk up enough to survive on their own. California sea lion milk averages about 35% fat, that's about the same fat content as whipping cream, and about ten times the fat content of whole milk. Not only does the thick layer of blubber the pups develop help keep them warm it's important as an energy reserve when they first strike out on their own.

Despite what this sea lion seems to be telling you, Cronuts are not 
a viable source of energy reserves.
Courtesy: Makitani via Flickr

The most important prey for lactating mothers are anchovy, sardine, and hake. These fish live in large schools, so they're usually plentiful and they have extremely oily flesh; perfect producing rich milk. In the past there were very large fisheries for these species off of California. Think Cannery Row on Monterey Bay. However, we aren't taking too much of the sea lions' food away anymore because canned, oily fish have declined in popularity.

I can't imagine why...
Courtesy: dr.coop via Flickr

 What's happened is that for the last few years the waters around the Channel Islands, where the sea lions give birth, have been abnormally warm. Each of the fish the sea lions rely on are cold water species, in fact North Pacific anchovy won't go into water warmer than 62 degrees F. Since California's seas have been so warm the food fish have shifted themselves to colder waters. Sardines have been spawning farther offshore and other fish schools have moved north. These migrations have forced mother sea lions to hunt farther afield, and when their moms don't come back for extended periods of time, the pups set out on their own too early.

So where are the dad's in all this? Why don't we see adult males stranding in California? Well they're not there. Male and female sea lions both take on long migrations from British Columbia to California and back every year, but they have different schedules. Females head down to the breeding grounds first to give birth. Then males head down to meet up with the females once they're ready to mate again; about three weeks later. Being further north for longer has actually lead to boom times for male sea lions. At the mouth of the Columbia river between Washington State and Oregon more than ten times the usual number of males have been hanging out. They came in for this year's copious smelt run and are fattening up to make the trip south to the rookeries. Males need a lot of mass and energy reserves to defend territories on beaches which they won't leave and thus don't eat for several weeks.

   "I'll calm when I haven't gone twelve days without food!"
Courtesy: Bridget Samuels via Flickr

So that's the story. Warm water pooling at the surface has pushed forage fish away from the Channel Islands. This means that female California sea lions have to travel farther to find food that makes rich enough milk for their babies. These longer trips mean that many young are leaving the rookeries too early, and are washing up along the shore. All the while, farther north, males are enjoying a greater supply of food than ever. The biological needs of its inhabitants, and the physical characteristics of the ocean come together to tell the complex story of an ecosystem as long as a continent. We're able to discover the changes happening in the environment thanks to this single species.

Scientists aren't sure if the warming is caused by the changes happening to the global climate system, or if this is part of natural variations of the Pacific. Either way marine mammal stranding networks will need support in the near future. If you want to help one of the best things you can do is to remain informed about who's best prepared to help hungry or sick sea lion pups. There's a good list of organizations to contact and a lot of information here.

References:

"California Sea Lion (Zalophus Californianus)", NOAA Fisheries: Office of Protected Resources. Accessed via: http://www.nmfs.noaa.gov/pr/species/mammals/pinnipeds/californiasealion.htm

Bernton, Hal, "Boom Times on the Columbia for California Sea Lions", The Seattle Times, March 27th, 2015, Accessed via: http://www.seattletimes.com/seattle-news/boom-times-on-the-columbia-for-california-sea-lions/

"2013-2015 California Sea Lion Unusual Mortality Event in California", National Marine Fisheries Service Health and Stranding Reports,
Accessed via: http://www.nmfs.noaa.gov/pr/health/mmume/californiasealions2013.htm

Redman, Marianne, "The Pinnipeds: Seals, Sea Lions, and Walruses", pg 282, University of California Press, 1990.

Orr et al., 2011, "Intraspecific Comparison of Diet of California Sea Lions (Zalophus californianus) Assessed Using Fecal and Stable Isotope Analyses", Canadian Journal of Zoology, 89:109-122.