Invertebrate Mondays are the best Mondays!

Spring has sprung in Virginia and what better time for inverts to strut their stuff?

A snail and I take a walk in the woods.
A snail and I take a walk in the woods.
A marsh periwinkle hangs out.
I hang out with a marsh periwinkle.
A juvenile blue crab from a seagrass bed. May you're thinking, Hey, where's his other claw? It's locked on to my finger. It's the crab's version of holding hands.
A juvenile blue crab from a seagrass bed. Maybe you’re thinking, Hey, where’s his other claw? It’s locked on to my finger. It’s the crab’s version of holding hands.
A riffle of ribbed mussels.
A riffle of ribbed mussels.

Outbreak: Cancer of the clam

A soft-shelled clam.
A soft-shelled clam.

Cancer is not supposed to be a cold; it’s not supposed contagious. It may metastasize and spread from your face to your lungs, but I can’t catch it from you. For humans cancer isn’t contagious; for clams it is.

The clam, Mya arenaria, is the famous ‘fried clam’, a staple of clam shacks all along New England coastal roads. It also challenges our notions of cancer biology. Recently, a type of bivalve leukemia has been discovered, one that is transmissible between clams. Just as I can catch a cold from you, a clam can catch a cancer from its neighbor . Contagious cancer breaks our original epidemiological dogma of cancer that it stays within an individual and does not jump to another. Science is aware of only two other transmissible cancers – one in Tasmanian devils and one in dogs spread via venereal diseases.

What makes the clam cancer remarkable is its method of transmission. In devils and dogs (I wrote ‘gods’ at first, whoops!), cancer is transmitted via direct routes of fluid exchange (biting, sexual exchange). Clams are not known to bite or fornicate physically. The cancer leaves and lives outside the host floating on ocean currents long enough to infect another clam. It is unknown how long a cancer can survive outside the clam. Sperm cells in corals can last up to 4 months in the water. If cancer cells have similar survival then that means a movement of 100’s or 1000’s of kilometers on currents of cancer. Regardless if clam cancer cells move millimeters or miles, that they can survive in seawater outside the host is remarkable. Remember that when your wading the waters of Cape Cod this summer.

Fret not steamer slurpers and fried clam connoisseurs! A cancerous clam infects only other clams. We know of no cancers that jump from one species to another. Yet.

For the nitty gritty science: Metzger et al. 2015. Horizontal transmission of clonal cancer cells causes leukemia in soft-shell clams 

Ogre tree chomps on chains, Williamsburg, VA (3)

How to answer an ogre: or lessons you should have learned in 8th grade science

The tree looks like a petrified ogre caught in the act of eating chains. Like an ogre who might guard a bridge and when you try to pass asks you a math problem in a voice that sounds like he’s gargling gravel. If you answer correctly you will hear him say, “You may pass.” Get it wrong and you’ll hear your bones crunch in his chain-eating jaws.

You pound a nail into a tree three feet off the ground. If the tree grows 1.79 feet per year, how high up will the nail be in 4 years and 36 days (0.008 years)?

You have one minute to solve it.

The answer is three feet. Did you find yourself in the ogre’s mouth on the other side of the bridge?

Ogre tree chomps on chains, Williamsburg, VA (4)

The ogre was testing your 8th grade science knowledge. The reason the nail stays at the same height is because trees add layers at the top, not at the bottom. A tree grows taller from the apical meristem at the tips of branches and trunks. Roots elongate the same way, they add tissue at their tips. This is why a barbed wire fence nailed to a tree thirty years ago isn’t 20 feet in the air today. Or why those initials you and your wife carved into that oak tree saying you’ll be together forever in 1998 is still at eye level and why you now have to walk your new wife hurriedly past that tree hoping she doesn’t notice. But wait long enough and maybe the lateral meristem will cover your shame.

Trees grow taller from the tips and fatter from the outer layers. Stem and trunk diameters increase each year as a new layer of wood is wrapped around the tree. This is why – after a while – a tree looks like its chewing on barbed wire or old dog chain left behind by former tenants. The barbed wire stayed in place as the new layers grew past it.

Ogre tree chomps on chains, Williamsburg, VA (2)

The Mountain 2013 (61)
Nom, nom, nom.

Need a new yoga pose? Try the stretch spider!

The still brown grass crunches under my feet as I walk the salt marshes of the Goodwin Islands at the mouth of York River. I stop when when I see a blade of grass scramble across the other grass blades like a panicked airplane passenger who climbs over other passengers trying to get to the evacuation slide first. I snatch the panicked grass blade in my hand and it sprouts eight legs and repels from my hand down a silken thread, dangling for a moment like Christmas ornament before transmogrifying back into a grass blade. My grass blade is a spider in the tetragnatidae family. Tetra means ‘four’ and gnathid means ‘jaw'; it looks like it has four jaws but she doesn’t. See, science isn’t so hard once you crack the code. Tetragnathid (the ‘g’ is silent) spiders are also called ‘stretch’ spiders because they stretch their bodies in their own yoga pose: four legs forward and two to hold on and two legs back (some spiders try other combinations). Make yourself as thin as possible. And try to look like that grass blade or leaf or cattail.

I am amazed by this spider that looks like dead grass. I assume the yoga pose and combined with the drab-colored yoga outfit is to blend in to avoid detection by 1) potential prey and 2) potential predators. If she had not have scrambled, I would have never seen her. Even when I found her and made her pose for me on a blade of grass I still had trouble figuring out where the grass ended and she started. Look at that pose. Incredible strength and limberness. Stretch spiders can be found in your house, your backyard or your garden. So if you’re looking for a new twist for your boring yoga routine, run to the closet tree you can find, stretch out and see if anyone can find you.

This spider reminds me of another cryptic yoga pose: the toothpick grasshopper.


An open letter from Boston to the Gulf Stream: Knock it off

Car-eating snowpiles. nom, nom, nom, nom.    Thank you

Yesterday I wrote how warming ocean waters may be sending crabs into New England. But Bostonians and other New Englanders aren’t worried about a few crabs but car-eating snowpiles. The record snow is a gift, in part, from the Gulf Stream and the warmer than average temperatures in the Atlantic.

The screen shot below shows anomalies in sea-surface temperature with red to white being warmer than the average of the past 30 years. You can see the Gulf Stream (green ciricle) this year is white hot at nearly 60 degrees F, which is up to 20 degrees F higher than average for this time of year. Warmer water means more moisture in the air. The white-hot Gulf Stream is fueling the white cold of New England.

Look at the pretty swirls.
Look at the pretty swirls.

Running a hot bath sends more moisture into the air making the bathroom humid. A cold-water bath does not. If, after running a hot bath, you blast arctic air over it you’ve got yourself a snowstorm in the bathroom. And cold toilet paper. Apologize to your sweetie now.

Some of the snow clogging the streets of Boston started as warm water in the Atlantic, courtesy of the Gulf Stream.

How to keep warm? I recommend taking a hot bath, sipping a hot chocolate and clicking on the live link of the map to watch the soothing and mesmerizing ocean currents (you can go to other parts of the world too!). I also recommend looking at the wave heights which are just adorable. Who knew oceanography could be soooo relaxing…

The savory swimmer swims north?

A blue crab (Callinectes sapidus) found north of Cape Cod in 2012. Plum Island Estuary, Massachusetts
A blue crab (Callinectes sapidus) found north of Cape Cod in 2012. Plum Island Estuary, Massachusetts

In the summer of 2012 I was having dinner with colleagues when one offhandedly said that he’d seen a blue crab, Calinectes sapidus in the marsh (the Great Marsh in northeast Mass.). Incredulous, I said a more colorful version of, “Equine feces.” He was claiming that a blue crab was in the Great Marsh, far north of its northern limit of Cape Cod.

Then other sightings of blue crabs in the Great Marsh were reported.

I grabbed a long-handled net and walked the tidal creek bottoms. I saw many green crabs scuttle but then, in a deep pool, I saw a crab swim sideways and instantly knew it was a blue crab (blue crabs are in the family Portunidae which are swimming crabs with flattened back legs). I found three more that summer.

Finding a blue crab in the the Great Marsh was surprising because the marsh lies in the Gulf of Maine which extends from Cape Cod to Canada and is kept cold by cold water currents from Canada. Water too cold for blue crabs.

Using the list-servs, Twitter and colleagues I crowd-sourced information about observations of blue crabs throughout the Gulf of Maine and from 2012 – 2014 these often-called ‘Maryland’ crabs were found as far north as Maine and Nova Scotia. The reason? I hypothesize warming oceans. Water temperatures in 2012 and 2013 were much warmer than the average of the previous decade which may have lowered the temperature barrier. Earlier I reported on a similar range extension for the fiddler crab.

Solid line: historic blue crab distribution. Dashed line: potential new range extension.
Solid line: historic blue crab distribution. Dashed line: potential new range extension. Arrows indicate sightings of crabs from 2012-2014.

It may be a logical fallacy to talk about climate change and warming seas when Boston is undergoing record snows (record-breaking snows are consistent with climate-change theory as warmer air holds more moisture prior to storm events), but we cannot deny that the climate is changing. One prediction of climate change is that as the climate and oceans warm species will start shifting where they are found. We’ve seen this already in many commercial species such as hake, flounder, and lobsters in the northeast where the concentration of their biomass has shifted north. The Connecticut lobster fishery (CT the southern end of the lobster’s distribution) is severely depleted, possibly in part to lobsters moving north.

What makes my observations of blue crabs north of Cape Cod unique is that this is the first time a commercially important species has been reported to potentially expand into the Gulf of Maine. It should be noted that in the past 150 years there have been four other reports of blue crabs in the Gulf of Maine, but none of those populations were permanent. It’s still to be seen if the 2012 blue crab population is a permanent extension of their range. If so, then it means that crab cakes are expanding north thanks to climate change.

The blog’s title? Callinectes sapidus means ‘savory swimmer’.

The article can be found here: The savory swimmer swims north: a northern range extension of the blue crab Callinectes sapidus?

The winter sculptress

January 2015, Eastern Virginia

Ice covered marsh elder - Yorktown, VA, Jan 2015 (1)

The icy fog of winter swallows the Mid-Atlantic. The temperatures drop below freezing and weld the fog to all that it touches. Everything – limbs, leaves, porch steps, 1999 Honda Civics – are glazed with an 1/8 inch rime. Were I snail and one who could skate, I would don my snail sweater and skate (having only the one foot) and invite all my snail-skating gastropod-friends to my front steps and glide from one rail to another. Limbs sag heavy under the new weight. I – not wanting to skate on my steps – grab the rail. It too is slick with the icy slobber of a winter fog – and hold both my breath and myself as best I can. Winter redeems itself as an artist – the world now a garden of ice sculptures.

I scrape ice from my windshield with an bottle because apparently owning an ice scraper is much too much of a luxury. THe holes I make in the ice likely are not street legal as most of my view still obscured, but I take my chances and drive of to admire winter’s artistry.

Ice covered marsh elder - Yorktown, VA, Jan 2015 (3)

Of course I stop in the marsh. That is what you do when every surface you touch is lacquered with ice. Here in Virginia the Spartina stems – though dulled and browned with age – still stand. Today they glisten. Each leaf, each stem encased in a crystalline sheath. One that is cracked like, but intact. Like a mosaic of glass pebbles – each magnifying the beauty of which it clings. On the bushy marsh elder, each leaf is a glassy pendant.

Ice-covered Spartina - Yorktown, VA, Jan 2015 (2)

Ice covered marsh elder - Yorktown, VA, Jan 2015 (3)

My hands, without any sheath – glove or ice or otherwise – beg me back to the car. From the comfort of a defroster I admire what is now an icy meadow of marsh. By the weekend, the 50 degree temperatures will strip away the artistry of winter, each glassy sculpture losing its luster yielding to the rough concrete texture of winter’s true self.