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.
Namaste.

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.

Namaste.

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

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

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.

Strange underwater sex– sexual strategies of the bone-eating worm

Going deep today, folks.

Bone-eating worms. On bone. Photo courtesy of Greg Rouse via BBC Nature.

When you’re a bone-eating worm without a gut or an anus, and you live 10,000 feet under the ocean where it is big, dark and you’re stuck in one place, it can be hard to not only eat, but to mate. In such an instance one sexual strategy is for males to permanently move in with a female. This is the case of most bone-eating worms, Osedax spp.

First, let’s talk about this ‘bone-eating’ business. Osedax, which means ‘bone-devourer’, is a fingertip long worm that is found on the skeletons of whales and other vertebrates that have given up life and sank to the bottom. It’s strange enough to image that a worm eats bones, but even stranger to consider that it has no mouth to do so. The worm relies instead on acid. When a worm settles on a bone it sets out ‘roots’, fingerlike projections that secure it to the bone (FYI: the ovaries are in the roots too – where else would you keep your ovaries other than next to the acid?). From these ‘roots’ an acid is released and the nutritious lipids are pried loose from the bone and absorbed by the worm.

Things get even stranger when we talk about sex of a bone-eating worm (I never thought I’d ever write such a sentence!). When a set of bones makes its way to the bottom of the ocean from say a whale or someone made to walk the plank and all the flesh is gone, the larvae of the bone-eating worm, which have been floating on the currents begin to settle. The larvae are undifferentiated in terms of sex – they are neither male nor female. If a larva lands on the bone itself, it becomes female. If it lands on another worm its male. But males never develop into adults and therefore remain very small (up to 1000x smaller than females). The dwarf males live within the female’s tube and use the rest of the energy reserves in their yolk sacs to produce nothing but sperm. Each female can have up to 100 males in her harem.

The large differences between male and female body size is found in other animals such as the blanket octopus, Tremoctopus violaceus, where females are 40,000 times bigger than males. The most famous example is the deep-sea anglerfish, Ceratias holboelli, where the tiny male bites the female and fuses his mouth to her body. His organs shut down and all he does is produce sperm. Here are some true facts about anglerfish by zefrank.

As I mentioned above, having small males that attach to the females is a sexual strategy when mates are scarce (another strategy is to collect sperm and store it for later). For bone-eating worms, however, it may also be an ecological strategy. In an environment of scarce resources (in this case skeletons), stopping males from reaching maturity prevents them from competing with females for food.

Osedax rubiplumus. Large worm is female with an itty-bitty male harem in her tube.

We have to pause to admit that this a strange worm. One that has no mouth but eats bones using acid released from its ‘roots’ and where females collect a harem of immature males that do nothing but release sperm. All at the bottom of the ocean.

Now let’s add one more twist.

The strategy of having tiny males and big females is a recent evolutionary trend for the bone worm; their ancestors had males and females of similar sizes. A new study led by Greg Rouse from the Scripps Institute of Oceanography, however, suggests that the trend is reversing back to its ancestral ways. Evolutionary reversals are very rare in the animal kingdom. A new species of bone-eating worm, Osedax priapus, has been found to have independent and fully developed males of the same size as females. The males of this species compete for the same resource as females and now have the advantage of mating with multiple females. The reason for the shift back to ancient sex? More bones scattered on the seafloor and therefore less competition for habitat. Again, ecology is driving evolution at the bottom of the ocean. We don’t yet have a clear hypothesis why there are more bones in Davy Jones’ Locker.

Nature is simply amazing. And one day if you decide to become a marine biologist you can say things like this [these are direct quotations from the paper]:

“…sunken bones are most likely a limited resource.”
“…a bone-eating adult male can access multiple females, whereas a dwarf male is confined to a single female’s tube.”

When my bones are laid to rest, put me where the worms can have me. I would rather be habitat than bones in a box.

The Science:

Greg W. Rouse et al. A Dwarf Male Reversal in Bone-Eating Worms. Current Biology, published online December 11, 2014; doi: 10.1016/j.cub.2014.11.032

A unicorn in the marsh

A fiddler crab, tee hee
A rare species of fiddler crab

In the Great Marsh, he should be a myth, like a unicorn. But there he is. Like a nervous cuckoo clock in the mud, he pops out two or three times before he completely shows himself. A male fiddler crab (Uca pugnax), with a blue burnish to his shell and the characteristic obscenely large claw. I am astonished to see him. Astonished because I am probably the first person to see a fiddler crab pop out of the Great Marsh mud.

The Great Marsh stretches like a verdant yawn in the Gulf of Maine, which is the whole of the ocean from Nova Scotia to Cape Cod. Here the salty waters are chilled by the Labrador Current, a river of sub-arctic seawater that is born between Canada and Greenland and plunges south like a fist. The warmer waters from the south are deflected off the flexed arm of Cape Cod and kept out of the Gulf of Maine by the colder waters of the Labrador Current. As my New Englander friends like to brag, particularly when the snow is deep and the wind biting, this is a place only for the hardiest of souls.

Ovigerous (egg-bearing) fiddler crab, Uca pugnax, caught in a Rowley, Massachusetts, salt marsh
Ovigerous (egg-bearing) fiddler crab, Uca pugnax, caught in a Rowley, Massachusetts, salt marsh. Credit: Ashley Bulseco-McKim

Fiddler crabs are a warm-water species preferring the temperate waters south of Cape Cod. I am of the same opinion. I can snorkel in swim trunks in Buzzards Bay in July, which is on the south side of Cape Cod, but when I try to do the same on Cape Anne and its rocky shores, it’s like an ice cream headache for my entire body. I, too, am a warm-water species.

I search the mudbanks for other crabs, but find only him. Maybe he is a unicorn. An accident of currents and luck. Then I search other tidal creeks. Jericho, West, Clubhead, Nelson. Though their numbers are low, I find more fiddlers. Their burrows, only as wide as my thumbnail, perforate high in the mudbanks near the hairline of the Spartina grass. Many burrows are abandoned. Active burrows are identified by what look like chocolate ice-cream sprinkles – what we locally call ‘jimmies’ – scattered around the burrow entrance. These are fecal pellets from a recently fed crab. A quick probe with my finger (a very scientific technique, I assure you) confirms the fiddler’s residency.

I search beyond the Rowley marshes and find more fiddlers. Directly behind J.T. Farnhams’ in Essex. Off Atlantic Avenue in Gloucester. Chubb’s Point in Manchester-by-the-Sea. Next to the Endicott Square Shopping Plaza in Danvers. Massachusetts indeed has a new resident. So does New Hampshire as the fiddlers have journeyed as far north as Hampton.

Salt marsh fiddler crab, Uca pugnax, Manchester-by-the-Sea, Massachusetts
Salt marsh fiddler crab, Uca pugnax, Manchester-by-the-Sea, Massachusetts. Credit: Jon Whitcomb

How can a warm-water crab invade the province of the cold, a place where it has never before been able to survive? The answer lies in the fact that the province of the cold is becoming warmer. As the climate warms, so too does the ocean as the overburdened atmosphere gives some of its heat to the ocean to hold, an arrangement as old as the Earth. In the summers of 2012 and 2013 the Gulf of Maine waters warmed to 68 degrees Fahrenheit from the typical and chillier 63 degrees of years prior.

Those five degrees may not mean much to those of us who can adjust thermostats, but those five degrees are significant to an animal that uses the environment to regulate its temperature. For fiddler crabs, those five degrees are the difference between scuttling across the marsh and an arctic death.

Fiddler crabs did not arrive in the Great Marsh in the form that we recognize them, with their snapping claws and rounded bodies. They instead arrived as larvae carried by the currents and tides. The larvae are mostly heads, translucent triangles with Pinocchio noses and topped with a single spine, with legs and tails dangling. For fiddler-crab larvae, 64 is the key that unlocks the Gulf of Maine. Below that number in degrees Fahrenheit and these drifting triangles do not metamorphose into the crabs that make thumbnail sized burrows in the marsh. But give that number a degree or five, and those once-thought unicorns of the Great Marsh become a reality.

And so, borne on the currents of climate change, the fiddlers have made a surreptitious arrival to the Gulf of Maine and the Great Marsh.

The consequences of this incipient colony are unknown. As burrowers, fiddler crabs are engineers that re-work the soil and the marsh chemistry. If the effect is positive or negative is not yet known. I can only give you the answer that is common given by scientists that can be utterly frustrating:

It depends.

Too many crabs and the marsh grass cannot establish, which may ultimately lead to marsh loss. Only a few crabs and the marsh grass grows better. What I can tell you for certain is that with the arrival of these new colonists, just as when we arrived in the 1600’s, the Gulf of Maine and the Great Marsh will be changed forever.

Already we have seen marine species such as lobster, flounder and hake shift northward as a result of climate change. Some, however, still consider climate change a myth, like the unicorn. But sometimes seeing is believing. Like a fiddler crab in the Great Marsh.

The science is here: Fiddler on the Roof: A northern range extension for the marsh fiddler crab Uca pugnax