The cypress swamp

Darlington, South Carolina

Cyrpess wading in the creek (1)We walk through a cypress swamp full of trees that love to get their feet wet. Some are thick with gray shaggy beards of Spanish moss, while others are only tinseled with a sprig or two. Some trees wade in the middle of a creek, one that flows with water the color of sweet tea, though not nearly as sweet.

Village of knees

 

The walking path rises above a village of knees; stubby, leafless and unbranched versions of their tree parents. These cypress knees support the tree and let oxygen get down to the roots when flooded. A cypress tree doesn’t have to hold its breath underwater, it can breathe through its knees.

 

Swamp backbone (1)

 

Among the knees and trees is a backbone standing as straight as a soldier. It was formed by hogwire fence nailed to a tree long ago. The tree grew around the fence, died, rotted and fell away, but the hogwire held its backbone erect.     

 

 

Strip of bark in cypress swamp, Darlington, South Carolina
(c) Alison Gould

 

A strip of twisting bark stands as tall as roof. Though we don’t know how it stands because it is a bark without its tree, as though the tree was suddenly frightened and ran off leaving a strip of its backside behind.

 

 

 

 

 

 

 

Swamp rose

The swamp is abloom with flowers, but I am a poor botanist who just learned that Spanish moss is not a moss*. A red flower dots the swamp, a flower I will call a swamp rose, but it may not even be a rose. It may not even be a flower, just a moss masquerading as a flower, just as a flower masquerades as a moss – because Nature enjoys how clever it is.

 

 

Crane fly in cypress swamp, Darlington, South CarolinaA crane fly rests on a tree. The crane fly is sometimes called a mosquito hawk, under the impression that it eats mosquitos. I am a better entomologist than botanist and I know that a crane fly does not eat mosquitos. What I don’t know is how it got this mistaken identity because all I’ve ever seen a crane fly do is beat itself stupid against the drywall in my house until it successfully wrapped itself in spider web.

In the gravel parking lot a sign tells me about all the plants I saw, but I forget to remember all the information.     

 

*Spanish moss is not a moss but a flowering plant like daffodils in your lawn. Unlike the daffodil, it uses the air as its soil. Spanish moss is in the same family of plants as pineapples, the bromeliads, a family of epiphytes (means “living on plants”) that use other plants as habitats like lichen on rocks. They are a tropical plant-family that require indirect sunlight and little water, which is why my red-tongued bromeliad died when I watered it daily and put it in a bright, sun-filled, bromeliad-killing window. My bromeliad simultaneously drowned and burned to death. I told you I was a terrible botanist. For the Spanish moss, it may seem strange to have a pineapple as your cousin, but we all have a strange pineapple cousin who doesn’t quite fit but just like the Spanish moss, you can’t pick who’s in your family. If we could, there’d be a lot of lonely pineapples.

The mummichog: the first fish in space

This month I wrote a guest blog for Scientific American about the first fish to leave Earth’s gravitational grip, the mummichog, Fundulus heteroclitus. You can find it here. They published only the first half of the essay; the entire essay is below. 

A large mummichog, Fundulus heteroclitus, from the Great Marsh. 

***

When you launch a human body into space, sometimes that body become sick with nausea and general disorientation in the first few days. After a time, the body is better. This is the space version of seasickness. Because gravity holds our feet to the ground, we humans basically move in two-dimensions on Earth. So it may not be surprising that when you launch our bodies into gravity-free three-dimensional movement in space that our stomachs lurch and our heads spin. In the 1970’s the National Association of Space and Aeronautics (NASA) wondered how zero gravity would affect fish, animals that moved in three dimensions on Earth. Does a fish get space sick? For this important aquatic mission, NASA needed a fish that required little care but could endure the stress of a space launch and time in space. NASA first considered the goldfish, but they were not tough enough. NASA instead chose a drab, humble minnow found in salt marshes called the mummichog, Fundulus heteroclitus. It is not a fish prized as bait or aquariums so it is not well known. But if you’ve ever waded in the Bay of Fundy in Canada or Chesapeake Bay or the Gulf of Mexico in the U.S. and saw schools of minnows darting between your legs, then you met the first fish in space.

On July 28, 1973 at 7:11 a.m., the engines on the Saturn 1B rockets fired and the ground of Cape Canaveral, Florida, trembled. As the space shuttle lifted, the thrust pressed three American astronauts – Alan Bean, Owen Garriott, and Jack Lousma – into their seats. It also pressed the world’s first aquanauts, two juvenile fish and fifty fish eggs, against the walls of their small plastic aquariums. The rockets launched the astronauts and aquanauts into space for the second manned mission for Skylab (a mission confusingly called Skylab 3), the first scientific laboratory to orbit Earth.

When the two juvenile fish arrived at Skylab, they swam in elongated loops as though they were the spinning hands of a Salvador-Dali created clock. Without gravity the fish didn’t know which way was up. 

On the third day, the fish swam in regular patterns, always with their backs towards the interior lights of the Skylab. In many animals, including the two-legged kind that build rockets, gravity tugs on special cells in the inner ear and tell the animal which way is up (away from gravity). This is called the vestibular righting response. Without gravity to tug on their inner ears, mummichogs relied on artificial light to tell them what direction was up. Using fish logic this is reasonable. The sun never shines from bottom of the ocean.

Looping appeared to be the fish’s version of space sickness. Humans, like fish and other animals, rely on our inner ears for balance and orientation. When ocean waves or lack of gravity disrupts our signals, we become disoriented and often ill. As the mummichogs looped, the astronauts vomited. As the urge to vomit subsided in the astronauts, so too did the urge to loop in fish. By the fourth day in space, both human and fish had found their bearings. The fish swam in their small, plastic aquariums in space as though they had been there the whole time.

Would the unhatched fish be space sick and loop when they were born? The astronauts found out by their third week on Skylab, when 48 of the 50 eggs hatched. These tiny mummichogs did not loop. They immediately followed their older cousins and used the light for orientation. The fish fry having learned the up-is-where-the-light-comes-from-trick as embryos. Only when the astronauts shook the aquarium did the fish fry, apparently disoriented, began swimming in loops, only to return to swimming with their backs to the light.

I am a saltmarsh ecologist and know the mummichog well. It does not surprise me that the mummichog was the first fish in space. For the mummichog, space is only the next logical step for a fish that has tried to conquer land.

***

On a summer day 30 years after mummichogs become the first fish to swim in space, I found a female mummichog – just barely longer than my middle finger, which is large by mummichog standards – laying in the grass. Abandoned by the tide, she was as stoic as sea-glass. Death will do that to you. I picked her up and she jumped out of my hand. I startled, not expecting a dead fish to be so agile. I picked her up and marveled about how far she was from the water: at least 100 meters, what must be kilometers in fish-distance. I looked at the tacky-skinned fish in my hand. A tough and adventurous survivor. I walked to a nearby pond and drop her in. She swam away as though she’d been there the whole time.

I was in the Great Marsh in Massachusetts. At low tide, the Great Marsh exposes its broad mudflats. In tidal creeks, the water may be shallow as a big toe is deep. In the rivers and bays, water may be only deep enough for small jon boats. During this time mummichogs and other fishes and shrimps wait in what crowded pockets of water they can find. Competition for food is intense. As the tide rises into the rivers and creeks, mummichogs who have been waiting in the deeper waters of the subtidal, follow the leading edge of the water in a crowded, confused mass. In fact, the name ‘mummichog’ is a Narragansett word meaning ‘going in crowds.’ As the creeks and rivers fill, the crowded fish twist their bodies as they bite the mud for small snails and worms. On the larger spring tides the water overtops the marsh and pushes into the expansive, grassy marsh. Here the fish spill into the marsh and spread out an army raiding a village. The grasses offer a menu not available in the muddy creeks and rivers: insects and spiders and small crustaceans. A fish who takes advantage of this easy protein grows faster than those that remain in the muddy creeks and rivers.

A flooded marsh is a land available to any fish willing to use it. But a fish can get greedy and forage far from the safety of a river and lose track of time and tide. This greedy fish can be trapped in a net of interwoven grasses and dilly-dallying. A fish that can breathe air survives. A fish that can’t, won’t.

Ever since the first fish, which didn’t really look like a fish, found itself in the Cambrian ocean 500 million years ago, it had to occupy a niche, that space in the world where it can make a living. It’s not always a perfect fit. Some fish, like the tuna, found their niche in the big, blue water. Some, like the deep-sea anglerfish, went to the big black water of the abyss. Some fish found themselves pushed against a new habitat, one strange to those with fins and gills, land.

Over time, fish watched the crustaceans conquer this new habitat, which gave them a roadmap to do the same. The first step? Learn to breathe air. The ancestors of the mummichog developed a gill that drew oxygen from both water and air. Mummichogs have retained this ancestral trait, which is why after any given spring tide in the warmer months, it is not uncommon to find the grasses of the salt marsh sprinkled with these finger-length fish. A mummichog can withstand a land no longer underwater if there is just the slightest bit of moisture to wet its gills. In this way, a mummichog can make do on regular air until it is rescued by the following tide. I have accidentally left a small mummichog at the bottom of a bucket with so little water that it lay on its side. The next day it did not complain and when I plopped it into an aquarium it swam as though it had been there the whole time.

Mummichogs can be stranded not only on land, but also in water. Mummichogs take refuge from the snapping jaws of stripers and flesh-shredding teeth of blue fish (Pomatomus saltatrix) in the ponds that pock the marsh. These ponds are only flushed during the spring tides of the new and full moons. In the interim, the oxygen levels in these ponds, particularly in the summer, can plummet to nearly zero. Most other fish species die. The mummichog gulps at the water’s surface and survives.

Mummichogs use their intertidal life to incubate their eggs in the safety of grass blades and shells high in the intertidal. During the spring and summer months, a female mummichog may lay her clutch high on grass stems during the highest spring tides. As the eggs are cradled in the crook of a grass blade, they are well above the ebb and flood of hungry mouths. The eggs develop slowly and will persist in even the strongest of summer swelters. Once the sea rises enough to wet them, possibly even a month later, big-eyed and translucent fry emerge and swim away within minutes. This habit of egg-laying and hatching is so coded in the mummichog’s genes that eggs never exposed to air do not hatch.

Terrestrial life began first as an aquatic one and then an amphibious one. Intertidal fish like the mummichog conquered the first challenge of an amphibious life, air breathing. Conquering land required, quite literally, another step. The first animal with a bony skeleton to crawl from the water to see the trees and find dry soil under it, was possibly the recently found fossil, Tiktaalik. This fossil is commonly called the ‘fishapod’ because it looks like a fish flattened from the top and bottom that has fins like short, stubby legs. Among evolutionary biologists, it is a most famous and celebrated fish. The mummichog is not a jealous fish, but it may take some satisfaction in knowing that while anyone can walk to an east coast salt marsh and admire a living example of the first fish in space, one has to go to a museum to see the now extinct Tiktaalik.

Fish are not supposed to live on land. Just as humans aren’t supposed to live in space. Yet today we find fish that can live on land, even if only for a little while just as we can live in space, if only for a little while. In the halls of NASA and living rooms of dreamers, we talk about living on Mars, an inhospitable planet compared to our own. Yet we hope to conquer and inhabit this planet. To make it our own. This sense of exploration and colonization is not a strictly human condition; if we look back far enough we can see it’s in our fishy genes.

***

 

 

The spider and the hammock

hammock-and-the-spider-2Ten foot above the ground, a single glistening thread of spider silk streaks like a photon from one tree to another thirty feet away. The thread is an anchor line for a web built in an ornamental tree that is an island in a sea of grass. Why the spider chose this tree is known only to the spider. Perhaps the spider knew that it was out of the way of clumsy heads or hands of those animals that have six legs too few and live in square boxes. The web is remarkable not only its beauty but also the effort of its construction for a spider no more than half an inch in length. To set up its anchor line the spider climbed ten feet down one tree, walked 30 feet to another, and climbed another 10 feet up. All at the same time dragging a thread behind it that miraculously didn’t stick to the grass that it walked across. I can’t even tear off a piece of duct tape without it sticking to itself the first time. And that’s not the limit of my ineptitude as a spider . To accomplish the spider’s feat I would have to bungee jump out of the top of a sequoia tree, walk almost a mile to the next tree, all the  while, not to be too obscene, ejecting a continuous line of ½ inch cable from my rear-end, which I’m sure would worry the neighbors nervous, then climb back up another sequoia. I just don’t have that kind of stamina or determination.

I bought my wife a hammock, which requires its own special determination and stamina (in there is a joke about the special determination and stamina needed to co-exist with a significant other, but my better angels are shouting me down). My in-laws visited this past weekend and when I got home from work I saw my father-in-law*, who is not a spider, attaching the hammock to a pair of white oaks. Unfortunately, the white oaks did not anticipate our hammock needs when they were acorns and grew too close together. When I lay in the hammock I was immediately shaped like a V with my knees closer to my forehead than I am normally comfortable with. A slight shift in the hammock sent my legs twisting to the left and my torso to the right. At least my knee-forehead distance had increased. I looked like a picture of a cat that has just been dropped upside and is contorting its body to put itself right-side up to prove that cats always land on their feet. My feet and head weren’t sure which one was going to take the landing when I got out of the hammock. We contemplated another set of trees but they were too far apart. After some time and more holes in trees, we found the right combination of trees and level of contortion comfort.

hammock-and-the-spider
The hammock on the first try. The spider web and its judgmental eight eyes are out of the frame to the left. 

I imagine the spider watched as with some irritation as we discussed and debated how to hang a hammock, something that we didn’t even build ourselves. Likely, it rolled all eight of its eyes as it busily spun a beetle in a body bag of silk.

******

*Here it is best that I note that I was worthless in the hanging of the hammock other than testing the quality of its hanging and pointing out that a spider did it better and then blogging about it. The hammock is now in a perfect spot, no thanks to me. Some father-in-law’s have all the luck. 

Ghost Forests of the Chesapeake

Chesapeake Bay, Virginia

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Skeletal trees tower over the salt marsh, their bare arms outstretched like scarecrows. The salty sea wind polishes their chalky bones. The skeletons loiter like teenagers in the middle of the marsh – bored, out of place and suspicious. Trees, whether dead or alive, are not supposed to be in the grassy plains of the salt marsh unless elevated on a hill. Dead trees that appear in the middle of nowhere like fairy rings or Stonehenge hint at the supernatural; but these ghost forests are impeccably natural.

Throughout the Chesapeake ghost forests line the edge of salt marshes or sometimes rise up like specters in the middle of a marsh half a kilometer from the nearest forest. These are corpse-filled forests created by the sea where dead trees mean new life for the salt marsh.

ghost-forest-salt-marsh-severn-virginia-15

Salt marshes chose real estate at the edge of the sea. And like any real estate at the ocean’s edge, it has to deal with not only flooding, but also a rising sea. A salt marsh has the same options as a house to deal with a rising sea: build vertically or move to higher ground. But the higher ground is often occupied by forests. A salt marsh wants to invade the forest and take over its land, but the tree is greedy and grabs sunlight by the armloads, leaving little energy for the forest floor. The salt marsh’s advantage is its ability to tolerate salty land and so it stays in the lowlands. In a rapidly rising sea, however, the salt marsh is caught between a woody devil and a not-so-deep-or-blue sea. One key to the marsh’s survival is patience and opportunity.

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The skeletal remains of trees on a muddy beach on the Goodwin Islands, Virginia. Here the sea not only rose to kill the trees, but also eroded the marsh edge exposing trunk and roots alike.
goodwin-islands-va-sea-level-rise-1-copy
The same muddy beach, which serves as a tree graveyard.

The sea has no politics. It does not care about borders and territory and competition between bickering ecosystems. As it rises, it slips past the forest boundary to bathe trunks and roots in brine. In time, trees will die, shedding their light-grubbing leaves, bathing the ground in solar energy. Awash in sunlight and without competition with tree roots, the salt marsh grasses march in and encircle woody trunks as bark flecks and falls away. Trees have always been stubborn and don’t easily give in to gravity or mortality and will stand tall over the marsh long after their phloem no longer flows, continuing to stake their claim even in the afterlife.

The movement of marshes into higher ground, especially into forests, is called marsh migration and is an important mechanism for salt marshes to escape a rising sea. Where a forest sees death, a marsh sees life. A salt marsh does not fear a ghost forest; it fears a hill, a seawall, a Food Lion parking lot, and a road – anything that prevents its escape against a rising sea.

Post Script:

Ghost forests can be found anywhere in the world where there are salt marshes, not just in the Chesapeake. There is a great post on saltmarsh migration by Joe Smith from New Jersey. There are also two great scientific publications on saltmarsh migration. One by  Joe Smith and the other by Matt Kirwan at the Virginia Institute of Marine Science.

 

Wait, snakes wear stockings?

A younger and more reckless me used to say ‘garden snake’ when I meant ‘garter snake’. What’s the different between a garden snake and a garter snake? There is no recognized group of snakes called garden snakes. A garden snake is any ole snake you might find in your garden – be it a corn snake, a milk snake or a deadly black mambe. A garter snake is a group of snakes belonging to the genus Thamnophis. How did my older, more considerate self remember the difference? I thought of a snake wearing a garter belt to hold up its stockings. Well, stocking. The most common garter snake is the eastern garter snake, Thamnophis sirtalis. It is harmless and only likes to eat frogs, tadpoles, and insects – not people who can’t remember its name.

Here is a garter snake in Williamsburg, Virginia, that surprised me while I was hunting frogs outside of Jamestown Pies while I waited for my pizza to cook (frog hunting is an activity of opportunity). 

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And here is one from Newbury, Massachusetts, that emerge just as spring was happening. It was still cool and he let me lay inches from him and take his picture. I made sure to get his good side.

Common Garter Snake, Thamnophis sirtalis, Newbury, Massachusetts (6)

On the lacewing

Last week I saw fuzz on my windshield. My car does not suffer from the disease of cleanliness . I smudged the fuzz across my windshield, which added to the decor of bird poop, glass chips and cracks. More fuzz. Just as my thumb went into action, I paused. I recognized that fuzz. I leaned closer and focused on the fuzz. It wasn’t fuzz, but several strands of what looked like thin monofilaments of fishing line with slim, yellow jelly beans hanging at the end of it. There was about a dozen jelly beans dangling from my windshield (and at least one smeared).

This was not fuzz. This was eggs (yes, I know it’s not gramatically correct). Eggs of the green lacewing (Family Chrysopidae). I had left my windows down overnight so the interior could enjoy the fresh night air (read: air it out because I left some unknown food in the floorboard). The green lacewing was drawn to my car as the perfect nesting sight. No predators there. For the past week they have gone with me to work. Little jelly beans stuck at the end of a frozen bungee cord. They sitting there in my line of sight, me wondering when they will hatch and what they will eat when they do (I should have left the food in there!). 

The lacewing is a delicate and beautiful insect that is well-named. And the aesthetics of its egg-laying habits serves a more important purpose than beauty. Just like a Kit-Kat is safer from me when it’s on top of the fridge instead of on the counter, tethered lacewing eggs are safer from predators than those laid on directly on the leaf.

Below are images from my car. Below those is a better picture of the eggs (courtesy of http://bugguide.net/) and one of the adult (courtesy of http://www.cirrusimage.com) .

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And this is what they will look like when they emerge (courtesy of http://www.bugguide.net/).

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