Monday, October 27, 2014

They're in the Trees Man!

It's autumn here in the Northern hemisphere, and in the Pacific Northwest many of our salmon species are making their return to the rivers they were born in. This amazing phenomenon has been well documented on TV, but there is an incredibly cool piece to the story that's often missing. One that weaves the ocean, the river, and the land together and shows us that nothing is alone in the environment.

Pacific salmon are a pretty cool group of fish, but honestly it can be really hard to agree on just what the heck a salmon is. This confusion comes from old terms for the same fish doing different things. Ever noticed how salmon and trout look almost exactly the same on the outside? Well that's because they pretty much are. All trout, salmon, char, freshwater whitefish, and graylings are part of the salmonid family. Amazingly many of these fish can spend their entire lives in freshwater, or they can spend part of it in fresh and part out at sea. Fish that have a life cycle which takes them back and forth between salt and fresh water are called anadromous (pronounced an-ad-row-muss) fish. Weirdly enough some species have a freshwater exclusive and an ocean going form, and they get different common names because of it. For example a rainbow trout (Oncorhynchus mykiss) lives in freshwater exclusively, but a steelhead (also Oncorhynchus mykiss) goes from fresh to salt and back again. It's genetically the exact same fish, but because steelhead fill up on tasty ocean plankton they get much bigger and their meat turns a lot pinker.  

"I haven't decided which I want to be yet. I'm taking classes in both and seeing which I like more."
Courtesy Ingrid Taylar via Flickr

Honestly the rest of this post could be about what is and what isn't a salmon, but that can get tedious and there's other things to get excited about this week. In general when people talk about Pacific salmon they're referring to one of five different species, which are all in the genus Oncorhynchus which means hooked nose. These are the coho (O. kisutch), pink (O. gorbuscha), chum (O. keta), chinook (O. tsawytscha), and sockeye (O. nerka). Aside from being many species instead of just one, Pacific salmon differ from Atlantic salmon (Salmo salar) by being terminal spawners. After they reproduce all five of the species listed above die. When I first learned this it seemed so sad and pointless to me. After all Atlantic salmon don't die after spawning, but it turns out the deaths of the adult Pacifics bring enormous amounts of nutrients into inland environments. 

"It's cool birds, I wasn't using my eyes anyway."
Courtesy Lewis Kelly via Flickr

When thousands of salmon flood a stream and die there, their bodies begin to decay in the water, but look at that picture above. Where's the shore? That fish is lying out in the middle of the woods. Even if the shore is just off camera a few feet I guarantee that fish didn't have "walk on land" as part of his bucket list. So how'd he get there? Well the answer is probably a bear. 

Bears are good swimmers, they love the fattiness of salmon, and they don't mind scavenging on rotting food. Bears and other animals drag salmon away from the streams to munch in peace and the parts they don't eat mix into the soil. Then plants in the area pick up those nutrients and use them to grow. One study found that trees without salmon nutrients grew about 2/3rds as fast as those with them. So trees are, through salmon, taking nutrients from the ocean and using them to grow; and there are salmon streams that are as far East as Idaho (That's 450 miles in a straight line from the mouth of the Columbia River.) where oceanic nutrients can be detected in the trees. It's not just the trees either; studies have found oceanic nutrients in the shrubs, ferns, insects, birds, amphibians, fish, and mammals of these environments. 

No wonder we call him the King
Courtesy spappy.joneS via Flickr

The way we know know this is pretty cool too. Scientists use isotope analysis to see how much of a certain type of Nitrogen is inside the trees. You can kind of think of isotopes as sub-species of atoms. They're not all unique enough to warrant calling them something else, but they often behave a little bit differently. Different environments favor the production and preservation of different types of each atom. The ocean, as it happens, is very favorable to the form of Nitrogen that has an extra neutron. So researchers are able to burn samples from the trees and use a cool device called a mass spectrometer to figure out how much of their chemical composition came from the ocean. At one site in Canada they found that in some years up to 80% of the Nitrogen available for Sitka spruce (Picea stichensis) came from those years' salmon runs.

It's become increasingly clear that salmon are important for the health of Pacific forests. And the implication is astonishing. If we want healthy trees, that grow more rapidly, create more diverse habitat, scrub carbon from the atmosphere, and produce more lumber, then we want healthy salmon. Amazing large scale projects with that goal in mind are already happening, and keeping salmon streams healthy is as easy as making sure you pick up after yourself when you visit a river. It may be a long time before we see anything close to historic runs again, but so much is being done on every level of the community that I'm confident we can make a difference.

If that seems hard to believe, remember all of these trees are partly made of fish.
The world is way weirder and cooler than we ever expect it to be.
Courtesy ArkanGL via Flickr


"Family Salmonidae: Salmons and Trouts", The Burke Museum online

Reimchen, Tom, "Salmon nutrients, nitrogen isotopes and coastal forests", Ecoforestry, Fall 2001.

Reimchen et al. "Isotopic Evidence for Enrichment of Salmon-Derived Nutrients in Vegetation, Soil, and Insects in Riparian Zones in Coastal British Columbia.", American Fisheries Society Symposium, XX: 000-000, 2002

Moore, J, & Schindler, D, (2004) "Nutrient export from freshwater ecosystems by anadromous sockeye salmon (Oncorhyunchus nerka) Canadian Journal of Fisheries and Aquatic Sciences, Vol. 61, 2004

Sunday, October 19, 2014

Underwater Basket Weaving

Hey everyone, this week we're diving into a bit of a mystery. There's a pretty good chance that by now this little gem has come across your social media feed!

The original of that video had 8 million views on facebook alone last I checked. I've gotta say it's really cool that people are so curious about ocean animals. But the question on everyone's mind seems to be, as my mom succinctly put it: "What the heck is it?" Despite its facehuggerly appearance this is a native of the earth, or should I say the sea? What you're looking is a basket star. I should also mention that I'm not the first to identify this guy/gal. Both the Echinoblog, and IFLScience have tackled this mystery.

First off basket stars aren't actually a true sea star. You may remember from the post on catch connective tissue that sea stars are members of the echinoderm phylum. More specifically the sea stars we're most familiar with make up the asteroidea class (a class is one grouping more specific than a phylum) So if you're feeling pedantic and mischievous you can tell people you found tons of asteroids on the beach and not be lying. However the basket star is not an asteroid! Basket stars are part of a class of animals called ophiuroids (pronounced "off-yer-roids), and are more commonly called brittle stars.

 Jazz Hands!
Courtesy  Paul Thompson via Flickr

Even though most brittle stars look quite a bit like traditional sea stars, being in a separate class means they are as different from a true sea star as a sea urchin is. One of the most notable differences between sea stars and brittle stars is in how they get around. Sea stars use their hundreds of suction cup tube feet to grip tightly to the bottom and cruise along. Their rays (also referred to as arms) act as more of a platform for those strong tube feet to operate from. Brittle stars don't use their tube feet to walk. Instead they pick themselves up on their rays and stroll or slither like something out of the Nightmare before Christmas. Their tube feet lack suction cups and are used to grab food and help move it towards their mouth.

Basket stars are a really cool specialized group of brittle stars. They are well adapted for collecting plankton out of the water with their arms. In the above video you can only catch the view for a second, but at one point the basket star opens all its arms, and you can see the central disk. The disk is pentagonal and one trunk-like arm grows out of each side. Each of those five arms then branches dozens of times to create a wide net. The arms of the basket star are covered in microscopic hooks, a nice coating of mucus, and are capable of coiling around themselves to form traps that hold onto their planktonic prey. Below you can watch as some euphasiid shrimp are added to a basket star's tank at the Seattle Aquarium.

That video is a little sped up, but you can see how those branches form a wide net and are waved back and forth to sweep for more food. Grabbing food out of the water like this is called suspension feeding. Sometimes you'll hear it called filter feeding, but that's a bit different. When there isn't an obvious load of plankton around them, basket stars usually cling to a hard surface or the branches of corals. They curl their rays up above their bodies into the current forming a basket shape. Hence the name.

What a basket ca...I'm not even gonna let myself finish that joke
By Peter Southwood (Own work) [CC-BY-SA-3.0 (], via Wikimedia Commons

Once a basket star has enough food trapped on one of their rays they'll slowly move it towards their star shaped mouth. Incidentally brittle stars don't have an anus, so they excrete their waste through the same hole they consume food. Anyway inside the mouth are five sets of comb-like teeth. The star slides its arms over the teeth and the prey are scraped off like frosting from a fork. Am I the only one who does that? I can't be the only one who does that.

Basket stars are found throughout the world from shallow water to the abyssal plane. The one from the original video is probably Euryale aspera which is a shallow living basket star found throughout the Indian ocean and tropical western Pacific. One of the things I think is coolest about basket stars is that they seem to have a strong association with a variety of coral species. Not only do coral branches make a good holding place for adult basket stars, they may even be an important nursery for juveniles. Young of the species most commonly found around N. America, Gorgonocephalus eucnemis, are usually found living just inside the polyps of the sea strawberry coral (Gersemia spp.). While this seems to be some type of symbiotic relationship, it isn't entirely clear if the little basket stars are stealing food from the polyp they're living on, or just using their mouth as a platform to feed from.


Stöhr, S., O’hara, T., & Thuy, B. (March 2nd 2012) “Global Diversity of Brittle Stars (Echinodermata: Ophiuroidea)” PLOS ONE DOI: 10.1371/journal.pone.0031940,
Accessed via

"What is that weird thing on facebook???" The Echinoblog

Gorgonocephalus eucnemis” Encyclopedia of Life,

"Gersemia” Encyclopedia of Life, 

Sunday, October 12, 2014

Sympathy for the Devil Fish

In case you've never heard the Rolling Stones song Sympathy for the Devil; go ahead and watch this video. Not only will having the song in your head make this post make a lot more sense, but it's also one of my favorite songs of all time.

Below you'll find the Depth and Taxa version of the lyrics. There's some ambiguity as to which animal I'm talking about, so see if you can figure it out before the end.

Please allow me to introduce myself
I’m a fish with planktonic taste
I’ve been around the whole wide world
Swum many a mile ‘cross the wastes

And I went  down to Africa
From the Azores, out at sea
Made the trip on currents
Courtesy Grant Bishop via Flickr
that pushed me ‘long, and let me feed

Pleased to meet you
Hope you guess my name
But what’s puzzling you
Is the fact that I’m so tame

We’re all ovo-vi-vipar-ous
When we know that it’s time, to give birth
Got a real long gestation
Often times, it’s two years

My bat like wings
Are the perfect things
For the heaving seas
That I slowly swim
Courtesy Kevin Bryant via Flickr

Pleased to meet you
Hope you’ll guess my name, oh yeah
Ah what’s puzzling you
Is the fact that I’m so tame, oh yeah

I made the list
When your scientists
Noticed the decline
Of this group of mine
Men shouted out,
“Look at those devil horns!”
When really they
Are ce-pha-lic fins

Let me please introduce myself
I’m a fish of planktonic taste
And I’ve been trapped in big drift nets
Who just write me off as their bycatch
Courtesy William Warby via Flickr

Pleased to meet you
Hope you guessed my name
But what’s puzzling you
Is the fact that I’m so tame

Pleased to meet you
Hope you guessed my name, oh yeah
But what’s confusing you
Is the fact that I’m so tame

Just as all true seals are the phocidae
And all the squalids, sharks        
We're devil rays
just call me Mobula
Cause I’m in need of some defense

So if you catch me
Have some courtesy
Have some sympathy, and instinct
Use all your well-learned fishing tricks
Or I’ll end up, gone extinct, oh yeah
Courtesy Patrick Neckman via Flickr

Pleased to meet you
Hope you guessed my name, oh yeah
But what’s puzzling you
Is the fact that I’m so tame

So did you figure it out before the end? The animal is, of course, the last image: the giant devil ray (Mobula mobular). I hope you enjoyed the different format this week. If you have questions, or you'd like a little bit more traditional post about these beautiful fish, let me know in the comments!


"Skates and Rays" The Shark Trust

"Mobula moblar: Devil Ray" Encyclopedia of Life

Wednesday, October 8, 2014

Skin Deep

A calm ocean can seem uninteresting from above. At first glance it's this big expanse of basically nothing, but just beneath the surface lie wonders. The same can be said of sea stars. When we find them at low tide sea stars barely move. Many people aren't even sure that they're animals, and we regularly had people at the touch-pools of the Seattle Aquarium ask if they were fake.

 Well he does exaggerate how much he can bench, but I wouldn't call him fake
Courtesy Jerry Kirkhart via Flickr

  Right under the surface of sea stars, and the other echinoderms like sea cucumbers and urchins, lies what I think is one of the coolest adaptations of any animal on earth: catch connective tissue. This material is the source of echinoderms' amazing ability to become completely rigid, or jello soft.

Before we get into the meat of how this stuff works let's think about how it might be useful. At any one time different sections of a star's body can be rock hard, near liquid, and everything in between. This is an amazingly good strategy for an animal that moves over uneven terrain. Imagine you're a sea star and you're trying to find a tasty mussel to eat. As you crawl along your leading arm comes into contact with a big boulder. Well no big deal, you can make that arm go soft and bend to any angle you might need to climb onto it. As you reach the top of the stone you notice a strong current trying to blow you away. Again no problem, you can make a couple of arms go rigid to add strength to your grip which keeps you from waving around. Once you're held on nice and tight one of the arms that you're not using to cling for dear life can go soft and tap around the rock's surface in search of prey. Below you can see sped up video of a blue linckia star (Linckia laevigata) moving, and you can get a good idea of what I'm talking about. Check out how flexible the sections bending around the edges of the coral are, and how stiff the parts on the flat.

 Clearly this catch connective tissue is some useful stuff, but how does it work? In humans, our skin and connective tissues are made up of fibrils (small bundles of strands that make up a fiber) of collagen held together by connecting proteins.

Collagen fibrils (the big strands going up) and the proteins holding them together
Courtesy Zeiss Microscopy via Flickr

This is true for catch connective tissue as well.  The difference is that we have a more or less set amount of proteins holding the fibrils together whereas echinoderms can change the number of links. The more proteins holding the fibrils together, the less they can slide around on one another, and the more rigid the whole tissue. The fewer the proteins, the more the fibrils can slide around, and the softer the tissue. It's almost like bundling sticks with rubber bands. In what might be the greatest naming ever, the molecules that trigger the hardening and softening of the tissue are called tensilin and softenin. Many echinoderms can even reduce the number of proteins so low that they can literally walk away from sections of their body. This is called autotomy (dibs on the band name) and it's a great way to escape predators that might do much more damage by ripping off one of their appendages. Thankfully echinoderms have incredible regenerative abilities, so they can regrow parts of their bodies. There's a wonderfully quirky, yet easy to understand, video explanation of this incredible tissue at


Ana R. Ribeiro, Alice Barbaglio, Cristiano D. Benedetto, Cristina C. Ribeiro, Iain C. Wilkie, Maria D. C. Carnevali, Mário A. Barbosa, (September 14th, 2011) "New Insights into Mutable Collagenous Tissue: Correlations between the Microstructure and Mechanical State of a Sea-Urchin Ligament" PLOS ONE, DOI: 10.1371/journal.pone.0024822 Accessed via

Yasuhiro Takehana, Akira Yamada, Masaki Tamori, and Tatsuo Motokawa, (Jan 15, 2014) "Softenin, a Novel Protein That Softens the Connective Tissue of Sea Cucumbers through Inhibiting Interaction between Collagen Fibrils" PLOS ONE. 2014; 9(1): e85644.
Published online, DOI: 10.1371/journal.pone.0085644,
Accessed via

Dunn lab and Creature Cast