Why is Pisaster ochraceus (aka ochre star) so many colors? AKA they are what they eat!

(image by Nancy Sefton, NOAA Olympic Coast page)

So, early in my career during my various internships and volunteer time, I spent a fair bit of time at the educational tidepools exhibits at the California Academy of Sciences and Monterey Bay Aquarium.

One of the most common questions I would get about the commonly encountered "Ochre Stars" (Pisaster ochraceus) that live on the west coast of North America.

"Is there any significance to the color?" (or some variant thereof)

Well, its taken nearly 15 years but FINALLY...I can answer this question! I thank a neat paper by Harley et al. 2006 in the Biological Bulletin, which is available via Open Access!

So, here's the story!

This species lives along the coast from Alaska to California, including British Columbia, Washington, and Oregon.

These animals have a brilliant and very distinctive suite of colors that stand out. These include

PURPLE...

(image from Wikipedia commons)

BROWN (or RED)

and... ORANGE...and in fact, the species epithet, "ochraceus" in "Pisaster ochraceus" or the common name "Ochre Star" refers to the yellow-brown color, which was probably the living color of the the first specimens that were described of this species.

It turns out that the colors DO indeed VARY with region. Different places along the west coast have variable colors. Of populations they surveyed from 31 sites in California (North & South), Oregon, Washington, British Columbia, and Alaska. (diagram below is NOT proportional)

Across the surveyed sites, they found that on the whole MOST of them were brown-reddish with a relative minority of orange colored members as part of the population.

Curiously, those in certain isolated channels..in Georgia Strait (British Columbia) and Puget Sound (Washington) were 95% PURPLE!!

(image from Wikipedia commons)

In addition to color, they further examined other factors: food, size, and injury. And ran them together with a cluster analysis.

And they got a diagram that showed overall similarity between members from each of the different sampled study sites.

(Fig. 3 from Harley et al., 2006)

There was a close association between all of the populations in California, Washington, and Oregon (seems like Alaska was omitted).

The Georgia Strait and Puget Sound populations (the purple ones) clusters together AGAIN.

COULD these purple populations be something new or different???

A logical question to ask at this point. Did this separate purple population or ANY population of this species have enough separation or structure to warrant consideration of a new species??

So, The study looked at population genetics of P. ochraceus.

That is, the amount of genetic structure was present in the various populations within the species across its distributed range.

(image by Nancy Sefton, NOAA Olympic Coast page)

Essentially, there was NO structure of populations across the range.

That is to say, that an individual from San Diego (southern range) and an individual from Alaska (northern range) were really NOT all that different. Gene flow between populations remained high (that is, no subset of the gene pool had been significantly isolated)

They found NO "obvious" relationship between color and each population.

So, to put it in much simpler terms- There is no color (or other) subset of this species that has become isolated enough that its about to become a separate species or even a genetically separated population.

WHAT's going ON with the PURPLE ones then????

One of the coolest conclusions of this paper was that COLOR in P. ochraceus is probably related to what individuals of this species ATE.

So, it turns out that individuals from California, Oregon, and Washington?

They enjoy eating The mussel Mytilus californianus

(image from Wikipedia commons)

...and now we get to the PURPLE ones from the isolated inlets in Georgia Strait and Puget Sound. What's different about these isolated areas that's different from the open ocean populations?

THEY AIN'T GOT NO MUSSELS!!!

Instead, they have ACORN BARNACLES!! (Balanus spp.)

(image from wallawalla.edu)

The immediate correlation seemed to be that this ecological/external effect (i.e., food type) was the reason why you get purple Pisaster ochraceus. It turns out that the mussel Mytilus contians carotenoid pigments, which are the same KIND of pigment that are responsible for the orange color in carrots!!
Harley et al. hypothesize that the mussels provide the pigment that yields the light orange/red color

(from MarineBio.net!)

and that those ochre stars deprived of mussels REVERT back to the bright PURPLE color!!! (note that mussels are absent in the pic below!)

They point out that the color still varies among individuals-some orange, some red/brown, and some in between. So, there might yet be an underlying genetic component to the variation in color.

They add anecdotal accounts that some orange adults turn purple when held for long periods under laboratory conditions and that small individuals of Pisaster are actually not fixed on a color. So SIZE and maturity may also be important factors.

But the authors save the best for last. They also speculate that those factors that affect color are apparently stable over relatively long ecological time scales.
In some places, such as the famous Pacific Grove, California (home to Ed "Doc" Ricketts and Cannery Row), they were able to determine that Pisaster size, color frequency and diet have not significantly changed in over HALF a Century!!!

So, this famous population of sea stars has not undergone any real changes in prey abundance for the last 60 years or so!

2009 Pacific NW Expedition: "My God Its full of Stars!" (plus rocks)

So, if there's ONE thing I can say about this cruise?

I saw a LOT of deep-sea animals!

DEEP-SEA echinoderms!

ESPECIALLY starfish!

In fact, I'd say that its safe to say I've seen MORE deep-sea echinoderms (especially starfish) ALIVE on THIS single expedition then I've EVER seen on any single prior trip.
I've been on over a dozen deep-sea cruises, with both trawl nets and submersibles. Cruises that use trawl nets are great for collecting more specimens but are poor on observations of the animal in its natural state.

Subs, especially those which are manned, are GREAT for watching animals in their natural habitat and collecting animals in perfect condition but you ultimately don't get nearly as many specimens to study.
Remotely Operated Vehicles (ROVs), are in many ways more efficient than manned submersibles. Everyone can participate, you don't have a fraction of the science team up on the ship waiting for the others to come back and you have lots of room for storage. Plus, many of the newer ROVs can go much deeper then some of the older vehicles. (The Doc Ricketts can go down to ~4000 m or so)

What sorts of unique data can you collect exploring with submersibles that you can' t get with a trawl net??

1. Ecological Interactions. We got to see this at least twice (to my memory) but here we have an OUTSTANDING photo from the northern Cleft segment of the Juan deFuca Ridge (at about 3000ish? meters) showing predation in the deep-sea!! The big orange guy is the rare goniasterid Evoplosoma feeding on a Bamboo coral. You can hear the bamboo coral being eaten alive! Muahhahaha!
Evoplosoma is REALLY rare. There are less then a dozen specimens of this animal known. Now, not only do we know more about where it lives but we know what it eats.

You wouldn't be able to really see this from trawl specimens, much less get the specimen in perfect condition. Museum specimens of this animal are pretty badly trashed by trawl nets when they are collected.

2. Appearance of the Animal in its Natural State.

Up next...the strange "Slime Star" Hymenaster! These pix show it alive but really don't give you the full monty of just HOW frakkin WEIRD they are..
From the side view..you can sort of pick out the thickness and the little bumps that come off the top. Plus, as a bonus, we got to see it eating!

The entire body of this animal appears to be made out of a solid gelatinous material.
Hymenaster is like a jellyfish had sex with a sea star resulting in THIS thing:

and yes, its HUGE! Almost a FOOT across!!!

Close up? It looks like this. See those white rods? Those are some of the endoskeleton INSIDE this thing's solid-gelatin-like body.

In a closeup shot here..you can literally see THROUGH the body into the skeleton!!
You can barely tell, but there's an opening here called the osculum. Where the mucus comes out!!A strange and alien land under the sea...

Of the starfish..we saw several GIANTS!!

This brisingid (click here for background on brisingid biology) starfish was observed on President Jackson Seamount and was nearly TWO FEET across!! Some are thought to get to be almost TWICE this diameter!!
Not everything we saw was as big..but some were plentiful and eye-catching! This was also on President Jackson Seamount!! A pantheon of brisingids sitting on a sponge!!!

Brisingid starfish are suspension feeders-and so sitting on rocks, sponges, and other raised perches gets them into the current they need to feed !
Other big things?

This giant astropectinid (probably Thrissacanthias) from Pioneer Seamount! This beast was good sized as you can see!! (Gillian used for scale!)
Some of what we saw was familiar....Poraniopsis from the California/Washington/Oregon coast... Species to be determined!!
And what about NEW SPECIES??? Did we get many of those???

Honestly, there was a HUGE number of new taxa discovered! But for various professional reasons I can't post too many pictures of those animals here.

But here's one to tantalize all of you....a new genus and species of deep-sea goniasterid sea star living on sediment at a hydrothermal vent field!! You can see the vent clams in the background!!

It doesn't look like much from a distance, but up close- its a beautiful, sexy beast!So, what else did we see?? Lots of stuff!

CRINOIDS! (unstalkd and STALKED)!
oh yes..and we saw a FEW brittle stars. But only JUST a few HUNDREDS OF thousands...
We saw SEA urchins!! This particular one is an Echinothuriid which you can read about here!
Those of us on the cruise discovered that deep-sea echinothurid urchins can STING just like their tropical shallow-water counterparts!! So, be careful out there!

...and of course, we saw friable volcanic rocks! of MANY different varieties!! Deep-Sea lava! Glass! Yow!
We also took time to do some deep-sea pressure experiments!! Styrofoam cups to 2000-3000 meter depths change dramatically when all of the gas and porous space is crushed out of them!!!
But ya' know what's one thing you never run out of when you're out in the middle of the North Pacific?? Sunsets!!!! ( there's actually a sunrise in here as well!-can you tell which one??)

...and of course you have a bunch of PhDs out on deck taking pix of those sunsets for their scientific talks!!
....For many of the other science team members, the return to land meant the end of the expedition. But for many of us..the data collection and the specimen analysis will be used for analysis and study for YEARS.

Almost NOTHING (from a biodiversity POV) from this area had been known previously.

and now?

Much of the preliminary on-ship study suggested that a LOT of the animals collected were new.

New species and in some cases, new genera.

New behavioral observations.

New records.

The cruise is over but the discovery (and the excitement) is just beginning!

2009 Pacific NW Expedition: What Happens Next? Waiting & Recovery!

So, when last we left off...the ROV Doc Ricketts had been deployed into the depths! We did this almost EVERY day we were out.

We were pretty much on track with the expedition for the first half of the dive. Got to see several of the targeted northern seamounts- CoAxial, and North Cleft...but weather out there can be tricky and we ended up moving south to President Jackson and then gradually down to the Northern Escanaba Trough (called NESCA) and then eventually a final day at Pioneer Seamount close to the California coast. Most everyone, then focused their attention on the dive depending on what the priorities for the diver were that day.

(photo by Soureya Becker)

The ROV control room becomes THE Place to be during these dives and if you had any kind of science being done, it was usually in your best interest to be there for the whole duration. You can see me there on the right with my left hand on my chin.

The control room is a clean dark room with lots of big "super villain base control room" type hi-resolution plasma TV screens showing input from about a dozen different cameras located on the Doc Ricketts IN addition to the control monitors (many with touch-screen controls!), various control panels, joysticks, video monitors, video recording devices, and so forth.

Among the control room amenities: very comfortable First Class airplane type chairs in the back, a comfy rug, lights off during operation, and is LITERALLY the coolest place on the ship (because the AC needs to be on) when everything is go.

So, what do you see? A lot of stuff like this:

Stunning geology...

(lava pillars supporting crust from a drained lava lake from the MBARI expedition blog)

And one amazing sponge after another!

(crinoids on a "goiter" sponge from the MBARI expedition log)

Shown here: When I was around..we observed and collected deep-sea starfish, such as this very large and gelatinous Hymenaster (which I will talk more about later this week-but if you are impatient-you can see the write up I wrote on the MBARI expedition log)

(photo by Soureya Becker)

Some of my colleagues had the dazzling sense to actually take pictures of the video screen shots as they were happening!

The ROV pilots used one of about 3 different devices-two mechanical arms, and a suction sampler to collect stuff onto the submersible.

(photo by Soureya Becker)

I'll tell ya' the truth though. NO one can sit in a completely dark room full of TVs for 10 hours straight. Especially when you've got a lot of days that look like this outside: ...and on some days, you actually have some company.. You can barely see it, but that was the Woods Hole Research vessel R/V Atlantis hanging off our port side aft. and also, you occasionally see dolphins, whales, mola molas, etc. But ultimately, you don't NEED to be in the ROV control room all day.
Sometimes they do "geology" when you do "biology" or othertimes, they just have other stuff going on..But you're out in the middle of the North Pacific with nary a shopping mall in sight!

So what other stuff do you do?

1. Relax. There's always just crashing in your bunk in your very cozy stateroom. This was especially popular the first few days when motion sickness was still pretty common. 2. The laundry. The Western Flyer had state of the art laundering technology available! I used them a bunch of times! 3. EAT! One of the most important personnel on the ship was Patrick, the steward (who is also trained as a fully trained Marine Geologist). One of the smarter personnel who found a creative way to get out to sea to observe cool rocks! Patrick kept breakfast, lunch and dinner ready on time every day. I've yet to be on a research vessel that didn't have above average day to day meals and MBARI did NOT disappoint...

(photo from MBARI's 2007 Seamount expedition)

4. WORK!

You could still get internet uploaded twice a day, image files to organize, and all sorts of other work that needed to be done. There's a designated workspace for everyone to be busy... Above we see Dr. Dave Clague, chief scientist conferring with Gillian-one of the biology team specialists! and here is Dr. Craig McLain, writer of Deep-Sea news, here working on stuff!! blogging? writing mission reports? Power Point presentation? Craig worked so hard on this cruise I got tired of watching him after the first day!

...and then the ROV Comes back!! After letting the submersible pilots strap down and secure the ROV, the science teams head over to the storage compartments to inventory and take care of the rock and animal specimens collected on the trip. The big box on the left is largely used for rock storage. The two boxes in the middle-for storing animals...and the cylinders on the right are push-cores which were used for taking sediment samples and anything that happened to be sitting on them... There's also further storage that are out of view that will swing around on command and large bottles that are connected to the suction sampler. Suffice it to say...if you're down at 3000 meters for 10 hours you collect a LOT of stuff.. Here we see Chief Scientist Dave Clague recovering rock samples from the rock storage box.... By the time the ROV has returned, everyone knows it-and the science teams for both Biology and Geology are convened in the lab in order to prepare for processing... This includes biological samples-animal specimens. Shown being handled by MBARI technician Linda Kuhnz, a woman whom I have come to respect as having seen MORE Rathbunaster californicus (a deep-sea starfish from Monterey Bay) video then probably ANY single living person (myself included).

(Photo courtesy of the very talented Bernard Roth)

...and a stalked crinoid sample being processed by Dr. Julio Harvey and the aforementioned Gillian

(Photo courtesy of the very talented Bernard Roth)

and of course photos of me and Dr. Harvey discussing sciencey stuff while I look over some starfish at the dissecting scope...

(Photo courtesy of the very talented Bernard Roth)

Meanwhile, the Geology team breaks down the sediment cores recovered on the cruise...

(Photo courtesy of the very talented Bernard Roth)

and looks at rock samples recovered from the volcanic rock formations observed on the cruise! Many of which had critters living on them!

(Photo courtesy of the very talented Bernard Roth)

Processing is always a pretty intense process, often taking several hours to get everything completely done, even with everyone involved.

....Later this week: We wrap up with more rocks and some STARFISH!!