A Clam for Ken Kesey

"That's a CLAM!?" This reaction to a particular animal is almost guaranteed when people look at them for the first time. Check it out.

Oh man, who just leaves a tie-dye shirt laying around on a coral reef?
Courtesy: Nick Hobgood via Flickr

Okay first off, that looks nothing like what belongs in my chowder. Second, this animal just goes to prove that the 60's got to everyone. So where does counter-culture clam come from and why's it so psychedelic? Editor's Note: This post is greatly improved when accompanied by Strawberry Alarm Clock's: Incense and Peppermints, or your own favorite psychedelic rock song.

Well what you're looking at is a Tridacna (pronounced: Tri-dack-na) clam. They're more commonly called giant clams, but I don't really like that name because not all of them are giant. In fact one species, Tridacna maxima, has the common name "small giant clam"; that's just silly so were gonna stick with their scientific name for this post. Anyway Tridacna don't look much like their relatives, but all the pieces are still there. They have heavy rippled shells like their cousins the cockles, and the part that you see sticking out is their mantle (the body of a mollusk) and their siphons (The channels clams use to feed and breathe). These combined anatomical parts are what make up the "meat" of the clam that we eat.

Plankton filled water flows into the hole on the right, and strained 
water flows out of the tube on the left.
Courtesy edgeplot via Flickr

Tridacna clams live on coral reefs in the tropical Western Pacific. Once they settle out from the plankton they spend their entire lives in that single spot. They don't dig into the ground, but instead let it all hang out. Truly these bivalves (animals with two shells) have gotten the hippy lifestyle down pat.

In fact it turns out that Tridacna's trippy colors and patterns are essential to its survival. The reason Tridacna don't dig into the sand is that they're part of a self sustaining commune. Just like the stony corals around them; these mollusks host symbiotic algae under their skin. In order for the algae to photosynthesize they need to be exposed to the sun. The hinge of the clam's shell is heavier than the opening, so it can tilt face up and spend the daylight hours with its skin spread out in the light. The algae get protection from consumers, and the clam gets nutrients without having to feed. Having a backup way to get your food is especially helpful on coral reefs because the water around them is usually lacking in plankton. Completely clear water is great for snorklers' ability to see, but not so great for filter feeders' ability to eat.

"Come on baby light my zooxanthellae" -Jim Molluskson
Courtesy: Eric Johnson via the NOAA Photo Library

Now as anyone who's forgotten sun screen on a tropical vacation can attest, the sun at the equator is incredibly strong. Solar radiation in the middle of the day is so intense that photosynthesis can actually decrease as the clam's symbiotic algae try to protect themselves from sun burn. But this is a collective man, and the clam does its part to help the algae function efficiently.

The algal cells under the clam's skin are arranged in stacked towers, which is confusing because that means the cells on top shade out those below them. To counter this Tridacna have their own cool cells called iridiocytes (pronounced: ear-id-ee-oh-sites) which bend light in different directions. The iridiocytes reflect yellow and green light (which aren't used by the algae) away from the stacks, and reflect blue and red light (which are useful) towards them. Essentially the iridiocytes screen out the best light for the algae, soften its intensity, and evenly distribute it across the stacks of cells.

The combination of colorful algae and reflected light come together to create the mind expanding visual experience of looking at a Tridacna's skin. Cameras can't really capture how magnificently colored these animals are, so I really encourage you all to take a trip to your local aquarium and see them for yourselves. But here's another picture to tide you over 'til then.

  Couretsy: Nick Hobgood via Flickr

References:

Holt et al., "Photsymbiotic giant clams are transformers of solar flux", Journal of the Royal Society Interface, Oct. 2014, DOI 10.1098/rsif.2014.0678 Accessed via:

http://rsif.royalsocietypublishing.org/content/11/101/20140678 

Soo, Pamela & Todd, Peter A., "The behaviour of giant clams (Bivalvia: Cardiidae: Tridacninae)", Marine Biology, 2014, DOI 10.1007/s00227-014-2545-0 Accessed via:

http://link.springer.com/article/10.1007/s00227-014-2545-0/fulltext.html

Over the Moon...fish

If you're at all curious about the ocean, and let's face it you're reading this blog so you probably are, you're most like likely aware of the mola mola. Molas are also called sunfish thanks to their penchant for lounging at the surface like beach goers looking for a tan. 

That's fair, this is about what my thighs look like the first 

time I go out in shorts every year.

Courtesy: Sandip Bhattacharya via Flickr

So if there are sunfish out there, are there moonfish? That may sound like the kind of lame joke your uncle might make at a family dinner, but it's actually a valid question. And yes there are a couple of species commonly called moonfish. My favorite of these, and an animal I only discovered recently, is the opah (Lampris spp.). Opah look a little like mola, but they're completely unrelated.

Oooo, shouldn't have gone with the spray-on tan.

This fish is incredible. Believe it or not they're related to oarfish. If you've never seen them before, oarfish are anything but round and squat. In fact the giant oarfish (Regalecus glesne) is the longest of any bony fish, usually growing to 8 meters. It's believed that giant oarfish originated the legends of giant sea serpents. While they're generally pretty different; if you look at opah and the oarfish (dibs on the band name) side by side you can see a bit of a resemblance.

Talk about awkward family photos.

From Field Book of Giant Fishes 1949 courtesy: Biodiversity Heritage Library 

Both fish have those large dorsal (on their back) fins with a large crest in the front. They've also got long pelvic fins extending down from their bodies. It's going to sound incredibly unscientific to describe it this way but they're also both very shiny. The scales of these fishes are so reflective that their group name (Lampriformes) means the shapes of light. That reflectivity is really useful in both fishes' habitat, the open ocean.

Okay, so why are we not talking the sea serpent one? The opah just looks like someone took a belt sander to the edges of a tuna. Its tail is so small compared to the rest of its body it doesn't even look like it would help the opah swim. Ah, you're right imaginary snarky reader! Opah don't use their tail fin to propel themselves through the water. Instead they use their pectoral fins, flapping them up and down like a penguin! They're also massive, the biggest opah ever caught weighed over 300lbs. Yet despite their size and stubby looking fins opah have been recorded speeding away from predators at four meters per second. That's about twice as fast as most people jog.

In order to move all that mass around opah have powerful muscles behind their pectoral fins. The muscles are so burly that they look, and apparently taste, more like beef than fish; even though the rest of the opah's muscles are similar to those of tuna.

"Moo?"
Courtesy: Io [Public domain], via Wikimedia Commons

It's kind of incredible that we have a lot of information about what Opah taste like, and you can find plenty of recipes online, because we hardly know anything about their biology and life history. Opah live in deep water, rarely coming to anything shallower than 50 meters and they don't live in schools. Both those things make them especially hard to study. It doesn't help that during the day when we humans like to be awake, opah spend time at the deepest parts of their range foraging mostly for squid.

Most encounters with opah come from fisher people long-lining for tuna. Long-lining is a fishing technique where several-hundred meter lengths of line are dropped down covered in hundreds of baited hooks. Inevitably something other than the target species gets caught; thinking they're snagging a free meal. This is referred to as bycatch, and many bycatch species aren't commercially valuable, so they're thrown back dead. Fortunately for fishers opahs' tasty meat makes them very valuable and they're able to keep and sell them. You can watch some guys in Hawaii filleting an opah in the video below. Skip ahead to the 2:50 mark to get past the local TV shenanigans, or enjoy the dorky jokes and watch the whole thing.

The thing is we don't know how this catch affects the opah population. Some people think they're safe because there isn't a targeted fishery, and others think we don't know enough to say whether they're being seriously harmed or not. The Monterey Bay Aquarium's seafood watch program, which is well researched, recommends avoiding eating opah from international sources, and only occasionally enjoying those caught in US waters. This is because the US has some of the best fisheries management in the world, and lots is being done to cut down on bycatch.

References:

Lee, Jane, "Rarely Seen Moonfish, Size of Manhole Cover, Caught on Camera." National Geographic: Weird and Wild, February 5th, 2015

McClain et al., "Sizing Ocean Giants: Patterns of Intraspecific Size Variation in Marine Megafauna", PeerJ, 2015, DOI: 10.7717/peerj.715, Accessed via: https://peerj.com/articles/715/

Polovina, Hawn, & Abecassis, "Vertical Movement and Habitat of Opah (Lampris Guttatus) in the Central North Pacific Recorded with Pop-up Archival Tags.", Marine Biology, 2007 DOI: 10.1007/s00227-007-0801-2

"Order Summary for Lampriformes", Fishbase, 

Accessed via: http://www.fishbase.org/Summary/OrdersSummary.php?order=Lampriformes

What is a Seahawk Anyway?

You may or may not have seen that Chris Evans (Captain America) and Chris Pratt (Star Lord) got into a discussion on twitter over who would win the NFL championship today (I can't legally say the name of the event due to copyrights, yay!). Depending on which team wins the big game; one of their superhero personas will show up at non-profit for children with cancer in the other's hometown. Chris Pratt is from North of Seattle, and Chris Evans is from Boston. During the exchange Chris Evans asked a question that's actually pretty common even here in the land of the 12th Man. #whatisaseahawkanyway? Good question Chris, I think this week we'll answer that.

Seahawk (Superbowli repetensis)

It's not always the case with sports emblems, but the seahawk is actually surprisingly accurate to it's namesake.

 You were expecting it to be blue weren't you?

Courtesy: vladeb via Flickr

That bird is an osprey (Pandion haliaetus) and some of its alternative common names are: fish hawk, fishing eagle, and sea hawk. Now don't me started on the hilarious missed opportunity when we didn't call the team the fishawks, but otherwise this bird of prey is a powerful emblem for my home team.

If you feel like you've seen this bird before you probably have. Osprey are distributed world wide, from North to South America, and from Europe across Asia to Australia. The only place where these birds don't winter or breed is in Antarctica. There's only one requirement for these raptors to survive somewhere; fish. 

Osprey are almost exclusively piscivorous (piss-i-vore-us), not unlike that guy everyone knows who claims to be vegetarian, but doesn't count fish for some reason. Fish approaches 100% of their diet with occasional hors d'oeuvres of reptiles, rodents, and small mammals. The grace and power with which osprey catch their prey is astonishing. Their adaptations for hunting would make them pretty great football players as well.

Ugh this guy's Endzone celebration is really weird...

Courtesy: David Mills via Flickr

Osprey begin their hunts by circling above the water searching for the right place to strike. Not unlike Russell Wilson in the pocket, an osprey's eyes are perfectly adapted to find their target in all sorts of weather. The dark bars around their eyes help reduce glare (the charcoal football players use does the same thing) so they can see into the water. Once they've spotted a fish they have a couple ways they can catch it. There's the Richard Sherman style snag where they swoop down and snatch up their prey without getting touched by the water. You may have seen bald eagles do the same type of catch. Or they can go Beast Mode and crash directly into the water, talons outstretched in front of them, penetrating the surface to about 3 feet. This type of hunting is unique to osprey because most birds of prey can't scramble back to flight after getting wet. You can see both styles of hunting in this great video from Wildscreen.

They are so good at holding on to struggling fish because their talons are covered in minute hooks. These dig into the fish and make sure the osprey never fumbles. They also have another unique adaptation that allows them to get back to the air; wrists. They can bend their wings at a joint most other birds can't and that allows them to get lift straight out of the water from a dead stop.

Oh, Wilson's lost in the scrum at the line of scrimmage.

Courtesy: Jeff Bosco via Flickr

But wait he's managed to scramble out for a five yard gain!

Courtesy: Michael Utin via Flickr

So what are seahawks anyway? They're a unique and well adapted predator with all the skills necessary to dominate in almost any environment. Also they're a bird.

References:

Flemming, Stephen, & Smith, Peter, "Environmental Influences on Osprey Foraging in Northeastern Nova Scotia", Journal of Raptor Research, 24(3):64-67, 1990

Accessed via: https://sora.unm.edu/sites/default/files/journals/jrr/v024n03/p00064-p00067.pdf

"Pandion haliaetus, Osprey"

The Encyclopedia of Life

Accessed via: http://eol.org/pages/1049145/details

"Pandion haliaetus"

US Forest Service

Accessed via: http://www.fs.fed.us/database/feis/animals/bird/paha/all.html

On the Origin of Fish Face

Fish face. It's one of the first impressions we do of an animal, and the second you say those words almost everyone knows what you're talking about. Hands at the side of your head, cheeks sucked in, lips puckered, and moving your lips open and closed.

Yeah that's the one! Not really sure how the top hat fits in, but whatever.

Courtesy: Mark Norman Francis via Flickr

Opening and closing their mouth over and over is characteristic of many of the bony fish that we see most often, especially gold fish. Why are they doing that? Well they're breathing, and we're just seeing them getting water into their bodies. It's a bit like your stomach or chest going up and down as you breathe. When you make a fish face your hands on the side of your head moving with your breathing are mimicking an important part of the bony fish breathing system. It's not the fins (although I know that's what of lot of people are mimicking), and it's not technically the gills, it's the gill cover. It might seem like a silly distinction, but in fish the gill cover is as different from the gills as your nostrils are from your lungs. If it helps you can call the gill cover by its more scientific name, the operculum (oh-perk-you-lum).

To breathe, the opercula (plural) close and the fish creates negative pressure to pull water into its mouth. Then the mouth closes and the opercula open pushing water across the gills and out the fish's body. The gills themselves though, are the coolest part of this system.

This is either a fish gill or someone scalped Ronald McDonald.

Courtesy: Allan Reyes via Flickr

Gills are really amazing because they take huge amount of surface area and bundle it into a tiny package. One study found that Atlantic horse mackerel (Trachurus trachurus) can have 14 square meters of surface on their gills! That's a greater area than the floor plan of this guy's house, all packed into a 70cm long fish. How is that possible? Each of those red filaments coming off of that yellow arch are covered in microscopic sheets called lamellae (lam-ell-ay). There are a ton of filaments on each arch and even more lamellae on each filament. It's just another great example of how tiny things can really add up in surprising ways.

Scanning electron micrographs of filaments on the left and lamellae on the right

Courtesy: Evans et al. 2005

All of that surface area is very important to the fish's ability to breathe underwater. Fish don't actually breathe the water itself. It would take a huge amount of energy to break water molecules apart to get at the oxygen, so instead animals with gills breathe tiny bubbles of gas dissolved in the water. If you can't picture that, think about a soda bottle. None of the bubbles are visible until you take the cap off the bottle. Just like the horrifying amount of sugar in there; the bubbles are really small and surrounded by water. When the cap comes off the tiny bubbles expand, slam into each other, make bigger bubbles, and escape. 

The problem is that there's only a fraction of the oxygen available in air, in the water. So gills actually need to be more efficient than lungs at removing oxygen from their surroundings All of those lamellae are in contact with the water and have deoxygenated blood running just under their surface (that's why they're dark red). The blood has less oxygen in it than the water nearby so the oxygen moves from the water into the blood. Nature doesn't care for an uneven distribution. 

Communist implications of nature aside, it's a really efficient system for getting an essential chemical into the body. It's also great for getting waste out of the fish's body. Not only can CO2 leave through the gills, but other waste as well, nitrogen based wastes like ammonia especially. Even though fish do have kidneys that process waste; the gills are just so damn efficient at exchanging chemicals with the water that they actually excrete most of the fish's nitrogenous waste. In some species up to 80% of the ammonia and urea are excreted through the gills. Imagine if we only had to pee one fifth as often because we breathed our waste out. Netflix binges would be so much easier.

"Oh god! Is that what all these warm spots are?"

Courtesy: Alex Derr via Flickr

There's one more question I want to pose to you all this week. If fish breathe gas inside the water, why do they suffocate in dry air? It could be that their gills need to be wet to work. Which makes sense since our lungs are wet and protected from outside. But there's more to it than that. It could also be that it's harder for gasses and materials to move between two different media, in this case gas and liquid, which is also true. But one of the most significant reasons is that when a fish comes out of water the filaments and lamellae aren't buoyed up by the water and they lay flat on one another. When they bunch up, the surface area on the gills decreases, and the efficiency benefit is lost. So if you're doing catch and release fishing and you take your fish out of the water for a minute, slowly swish them back and forth a little in the water a little to help get their gills unstuck. That way he/she will stay healthy and have lots of babies so you can keep coming back every year.

References:

Evans et al., "The Multifunctional Fish Gill: Dominant Site of Gas Exchange, Osmoregulation, Acid-Base Regulation, and Excretion of Nitrogenous Waste.", Physiological Reviews, Vol. 85 No. 1, 2005, DOI: 10.1152/physrev.00050.2003

Accessed via: http://physrev.physiology.org/content/85/1/97

Hughes, G.M., "The Dimensions of Fish Gills in Relation to Their Function.", Journal of Experimental Biology, 45, 177-195, 1966

Accessed via: http://jeb.biologists.org/content/45/1/177.full.pdf

"Trachurus trachurus, Horse Mackerel" 

Encyclopedia of Life, Accessed via: http://eol.org/pages/206048/details

Mommy, Where do Baby Sharks Come from?

Let's start this week off with a little quiz, shall we? What's in the picture below?

"Sand." Alright smart-ass, what else? "Shells."

Courtesy: Patrick Feller via Flickr

If you said mermaid's purse, or shark/skate egg then you're right. All of those animals are part of the chondrichthyes (pronounced: con-drick-thees) class of fish.These fish have skeletons made of cartilage rather than bone. We talked a lot about chondrichthyes diversity in the very first blog post if you'd like to get a refresher. The name mermaid's purse applies to the egg cases of all cartilaginous fish because they're leathery, and most are rounded squares like a purse. The leathery-ness is important too because it's tough but flexible. This means the case is tough enough to protect the embryo, but is flexible enough not to shatter. Instead of nesting; skates and egg-laying sharks just kind of drop their kids off somewhere sheltered on the bottom and get on with their lives. That might sound mean, but mom's body produces a yolk that's so rich and full of nutrients that the babies come out of the case fully formed and ready to survive. (Editor's Note: Depth and Taxa does not condone abandoning one's children with 18 year's worth of food and calling it good.) Laying eggs is a method of reproduction called oviparity, and it's only one of several different ways of developing your babies, all of which cartilaginous fish are capable of.

Oviparity is pretty familiar stuff, but let's go over it anyway because it's the root of the other types of reproduction in sharks and their relatives. Unlike many of their bony relatives, chondrichthyans all fertilize their eggs internally. You can actually distinguish males and females of these fish because males have what are called claspers on their pelvic fins (the fins closest to where hips would be.) Claspers are used to hold onto females during mating and deliver sperm into her vent. (the multi-purpose opening of many marine animals.)

The claspers are the little finger-like nubs on the inside of the fins.

Courtesy: eustatic via Flickr

Once the eggs are fertilized they develop the familiar embryo and yolk combination you might have seen shining a flashlight through a chicken egg. Then, like we talked about before, mom drops the eggs off and they develop until they hatch. While inside the mermaid's purse the embryo has only the yolk for nutrients, so when it runs out the baby starts to get hungry and that helps prompt hatching.

Plus the WiFi in the ocean is terrible, so there's no Netflix to

 keep you perfectly still for weeks at a time.

Courtesy: Marian Gonzales via Flickr

 Of the four types of chondrichthyes; sharks are less likely to lay eggs than some of their relatives. All skates lay eggs, as do all of the chimeras. None of the rays lay eggs, and only about a third of what we commonly call sharks don't give live birth.

The next type of fetal development is a weird combination of eggs and live birth. For a long time this was referred to as ovoviviparity (pronounced: oh-vo-viv-i-pair-itty), but this term is falling out of favor because it implies the fetuses aren't getting any nutrients from mom. Recent research suggests that many, but not all, sharks and rays with this means of development contribute at least some nutrients to their babies. This can be through secretions from the uterus that the unattached babies absorb through their skin or consume, or in the form of unfertilized eggs which the developing young eat after their yolks run out. In at least one species the first fetus to use up its yolk will actually eat its brothers and sisters before being born!

"Don't mess with me man, I have seen some s**t "

Courtesy: Justin Morgan via Flickr

 What's consistent across these means of development is that the embryos are never physically attached to their mom. Most of the sharks that give live birth exhibit these strategies for developing their young. All of that is pretty weird and cool, but buckle up, 'cause we're about to take everything we just talked about and add another layer of bizarre.

The last means of fetal development is called placental viviparity. You read that right, placenta like in mammals. Placental development in sharks is a perfect example of one of my favorite concepts in biology: convergent evolution. Convergent evolution is when two very distantly related organisms develop similar traits or strategies completely independent of one another's genes. So even though some sharks have a similar fetal development strategy to mammals it doesn't mean we're related or that we got that trait from sharks.

Amazingly, in placental sharks, the embryos still start out with a yolk. Like other fish the baby shark starts off using up the yolk's nutrients, but late in this process mom's body supplies some of those nutritious secretions we talked about earlier. While her body does this, the lining of the yolk sac actually stretches out and fills with blood vessels. It reaches from the belly of the developing shark to the mom's uterine lining where it attaches and acts as the link between the two for gas exchange (getting oxygen in and CO2 out) and metabolism (getting nutrients in and waste out). This incredible strategy has developed in only a few species of sharks.

"Hey mammals, who's 'highly evolved' now huh!?"
Courtesy: Serena Epstein via Flickr

All of these strategies are spectacular means for getting chondrichthyan babies out into the world ready to survive from the second they emerge. By fully developing inside an egg or their mother; sharks, skates, rays, and chimeras have set themselves up as some of the most successful animals on the planet.

References:

Hamlett, William C., "Evolution and Morphogensis of the Placenta in Sharks", Journal of Experimental Zoology, 1989, vol. 252(S2), pp. 35-52

Musick, J.A. and J.K. Ellis, "Reproductive Evolution of Chondrichtyes", pp. 45-79, In: "Reproductive Biology and Phylogeny of Chondricthyes: Sharks, Batoids and Chimeras", William C. Hamlett, ed., Science Publishers Inc., Plymouth U, 2005

Accessed via: http://www.vims.edu/people/musick_ja/pubs/Repro_Evol_of_Chondrichthyans.pdf

Wourms et al., "The Maternal-Embryonic Relationship in Viviparous Fishes", pp. 5-10, In: "Fish Physiology: Volume XI: The Physiology of Developing Fish Part B: Viviparity and Posthatching Juveniles", W.S. Hoar and D.J. Randall, Academic Press Inc., 1988 

Stubby, Bobtail, Dumplings

Mollusks. Generally they're not a particularly cuddly bunch. For example, most people wouldn't call the inside of an oyster cute.

"D'aaaww who's a good boy?"

Courtesy: Larry Hoffman via Flickr

But there is one group among the mollusks that stands apart. The sepiolidae (pronounced seep-ee-oli-day) are an order of mollusks related to squid, octopus, and cuttlefish. More commonly these animals are called stubby, bobtail, or dumpling squid. None of the stubby squids get much bigger than around ten centimeters (about half the length of an unsharpened pencil), so they're round and small, which makes all of their common names very appropriate. The squid part of the name is a little misleading however because these animals show characteristics consistent with all of their cousins. They spend most of their lives on the bottom, like octopus; they have eight arms and two tentacles, like squid; and they have short rounded mantles, like cuttlefish. 

Who do you think you are? No, seriously I can't figure it out.

A Hummingbird bobtail (Euprymna berryi)

Courtesy: rtonyr via Flickr

Sepiolids are most closely related to cuttlefish which many people guess by the brilliant colors they can produce. Don't let the flashy get up fool you though; stubby squid are some of the best hiders out there. Not only can they change those colors to better match their surroundings, they're also master excavators.

Sepiolids are so cute that they even snuggle up in a blanket to sleep. They dig down by using their siphon (a tube coming from their body that they use to swim and breathe out.) to force water into the bottom and create a little depression. Then they settle down into it and use their arms to wrap themselves in a nice blanket of mud, leaving only their head sticking out.

Makes sense, you've got to wrap a dumpling 

to steam it properly

Courtesy: Nick Hobgood via Flikr

They spend most of the daylight hours tucked in deep water in their sandy beds and come out at night to hunt. Once they're on the prowl they'll often move to shallower water where they're sometimes encountered by lucky divers. 

So if they're this adorable as adults what do their babies look like? Well pretty much exactly like their parents. Dumpling squid have smaller egg clutches than many of their relatives. They lay up to about 50 eggs, which compared to a giant Pacific octopus' max of 100,000 is practically nothing. And unlike many of their relatives' babies, stubby squid don't spend time as a part of the plankton. The young sepiolids break out of their egg cases ready to roll, and walk away to find some food.

The eggs of the Pacific stubby squid (Rossia Pacifica) 

Courtesy: Chris Wilson via Flickr

You'd think that because these animals are so cute and charismatic that we'd know a lot about them. But because they live at the low end of recreational dive limits, are nocturnal, bury themselves, and tend to live on sandy bottoms which divers often ignore, we actually know very little about the lives of these cool little animals.

References:

Rodrigues et al., "Burying Behavior in the Bobtail Squid Sepiola atlantica (Cephalopda: Sepiolidae)", Italian Journal of Zoology, Apr 06, 2010

Anderson, Roland C.,  "Rossia Pacifica, Stubby Squid", The Cephalopod Page,

www.thecephalopodpage.org/Rpacifica.php

The Great Pacific Garbage Chowder

The Great Pacific Garbage Patch: it's flashy, disturbing, simple, a great band name, and... is completely misleading. That name was given to an area in the Pacific ocean by Curtis Ebbesmeyer when a colleague reported on the amount of floating plastic in the area. Because the name is so catchy it stuck, and has been used extensively in popular media reports ever since. So what's it look like? Well prepare yourself, below you're going to see a picture from the very heart of this trash zone that's been described as having a surface area twice the size of Texas.

Where's all the garbage?
Courtesy:  ---=XEON=--- via Panoramio

The problem with the term patch is that it suggests a covering, like in a patch of grass; or a lot of big pieces, like in a cabbage patch. Neither of these is what you see in these areas. Really what's happening is that giant ocean currents, called gyres, are concentrating tiny bits of plastic (called microplastic) in their middles. The gyres are more like plastic chowder than a plastic patch. And just like in a chowder the chunks aren't evenly distributed. Different types of plastic have different densities, so they float at different heights in the water column or even sink to the bottom.

This is the North Pacific Gyre. There are two major gyres in the Atlantic and Pacfic,
 and one in the Indian Ocean
Courtesy: NOAA Ocean Service's Making Waves podcast

So why isn't the plastic more evenly distributed, or at the very least why isn't it close to land? Well it has to do with the fact that the gyres are circular currents. When particles sit in water they are partly held up by how fast the water is moving. In swirling water, like the gyres or a cup of tea being stirred, the water at the center is moving slower than the water at the edge. Particles catch on the slow water and are pulled into the center where they stay more or less still.

 Red sprinkles in water before, during, and after stirring: Some sprinkles float, others sink; all concentrate into the center; just like pieces of plastic caught in the ocean gyres.

There are a number of issues associated with plastic in the ocean, and all originate with the fact that plastic doesn't biodegrade. Plastics are designed to last forever; they're stable, cheap, and sturdy. When we throw out plastic it never turns back into the minerals that it came from. Plastics just continually degrade into smaller and smaller pieces, but they stay plastic for functionally forever.
The first problem is that plastic takes up space. Several studies over many years have led to calculations of about 35,000 tons of microplastic and 250,000 tons of larger plastics in the oceans. All of those bits can easily lead to entangled marine animals.

The other big issue is that act of breaking down. As plastics break into smaller and smaller shards they're inadvertently gobbled up by smaller and smaller organisms, entering the food chain at more levels. While they're breaking apart and mixing around in the ocean, the chemically raggedy edges of the plastic grab onto many of the toxins commonly found in sea water. This takes those chemicals from their spread out, and therefore less dangerous, state to concentrated on one of these bits. Some of these toxins are hormone disruptors and there's a growing body of evidence that they can and will affect fish by changing their reproductive organs to those of the opposite sex.

Lastly, when plastic breaks down it becomes much harder to clean up. Imagine trying to separate all the parts out of real chowder, including the spices. Some of it can be picked out pretty easily, but others not so much. The microplastics are so small that we can't go out and grab it all because we'd have to screen the water with nets with really tiny holes. Nets with tiny holes are also how you catch plankton, so to catch the estimated 5 trillion bits of plastic out there we would probably decimate plankton populations.

"A few billion more of these and we can save and destroy the ocean at the same time"
Courtesy: NOAA Photo Library via Flickr

There's also the problem of some plastic sinking. For years surveys of ocean plastics weren't finding as much as researchers expected, but we knew that our waste was making into the ocean, so where was it all going? Well it turns out, straight to the bottom. A three ocean study of deep sea sediments has found significant amounts of microplastic fibers in the depths. A lot of these fibers were rayon and acrylic, materials found in synthetic clothing that probably got into the water from particles coming off as the clothes were washed.

Alright if we can't clean up everything then what do we do? Well the beautiful thing about this issue is that it's entirely in our hands. There isn't a single company or government that has caused all this pollution, so there's no one to fight with to make it stop. We are so powerful in this situation it's unprecedented. The most important thing is to stop using plastic like it has a short life. That tupperware you or your parents bought in the 70's and is still in your kitchen; that's how plastic should be used. Keep that sucker around forever and hand it down to your kids too. Those Legos that have been dropped, washed, stepped on, pummeled, and still haven't broken. Hell yeah that's my kind of plastic. Where you can, eliminate single-use products, and when you're out walking pick up a piece of litter each time. If we do these things we can make a dent in the 30% of all plastic that gets thrown away within a year.

I have to give credit to Edward Humes, author of Garbology for the term "plastic chowder" it really is a perfect metaphor.

References:

Cozar et al., "Plastic Debris in the Open Ocean", Proceedings of the National Academy of Sciences, Vol. 11 No. 28, 2013, DOI 10.1073/pnas1314705111

Accessed via: http://www.pnas.org/content/111/28/10239.full

Ericksen et al. "Plastic Pollution in the World's Oceans: 5 Trillion Plastic Pieces Weighing over 250,000 Tons Afloat at Sea", PLOS ONE, 2014, DOI 10.1371/journal.pone.0111913

Accessed via: http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0111913

Woodall et al, 2014, "The Deep Sea is a Major Sink for Microplastic Debris", Royal Society Open Science, 1:140317, http://dx.doi.org/10.1098/rsos.140317

Rochman, Chelsea, "A Story About Fish, Plastic Debris, and Sex", Deep Sea News, 2014,

Accesses via: http://deepseanews.com/2014/10/a-story-about-fish-plastic-debris-and-sex/

Humes, Edward, "Garbology", Ch. 5-6, Penguin Books, 2013