Category Archives: Animals

Saltmarsh amphipod (Orchestia grillus) on a Spartina stem. Brown is the normal color morph, compare to the orange, parasitized morphs. Plum Island Estuary, Massachusetts

Amphipods: the new menacing marine menace?

This week a young man in Australia was attacked by something while he was swimming in the ocean. His legs were bloodied and covered with hundreds of small bites. At the hospital, doctors were baffled about what bloodied the young man’s legs. The dad – who rocks in this story – went back into the water with a bloody steak and collected the small, flea-like animals. They were identified as amphipods, which are small crustaceans. If Sharknado has taught us anything, a movie about flesh-eating amphipods can’t be far now. Let’s see what that movie trailer might look like.

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A young, beautiful mother sits on the beach and watches her charming son, who she can’t believe is growing up so fast, swim in the ocean. Gulls wheel overhead and waves roll gently. The sky blue.

Boy: Mom, watch me swim.
Mom: Okay.

[cue the Jaws-theme music rip-off]

Cello: Duh-nuh

 Boy: You watching?
Mom: Yes, dear.

Cello: Duh-nuh

 Cello: Duh-nuh

 [cue that voiceover guy]

 That Voiceover Guy: Just when you thought it was safe to go back into the water again.

 Cello: Duh-nuh, Duh-nuh, Duh-nuh, etc.

 The boy screams and grabs his leg. His mother runs into the waves and pulls him out. His legs are bleeding but there’s nothing on them. A handsome and rugged marine biologist who looks just a little bit dangerous but you know you’d feel safe in his arms, runs over.

Mom: What did this!?

 Ruggedly handsome marine biologist: They’re amphipods.

 Mom: Oh my go…wait, what the heck are amphipods?

 Director: CUT!!

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What the heck are amphipods? They are small crustaceans related to shrimp and crabs and lobsters. Typically, they aren’t larger than your thumbnail. If you’ve picked up seaweed on a beach, you’ve probably seen them. They are the small animals flipping and tumbling around like fleas. Those are amphipods. Sometimes called ‘sand fleas.’ Or ‘beach fleas.’ Or ‘beach hoppers.’ Or ‘sea fleas.’ The ‘flea’ name refers to the shape of their body (pressed from the sides) and the fact that they can flip around using their tails.

The media has used the term ‘sea lice’, but that really refers to an isopod, which can be parasitic on fish and look like the rolly-pollies (aka doodle-bugs) you find under logs.

Are amphipods the new marine menace? A pack of ravenous, flesh-eating beasts that roam the oceans looking for prey? Well, no. They do eat flesh, but typically not live flesh. We marine biologists (both the ruggedly handsome and other variety) don’t think of amphipods as predators but as scavengers that eat dead plants and animals. They’re more like tiny vultures swimming through the sea looking for something dead to stick their heads into rather than wild dogs looking to tear apart a baby deer.

I study amphipods in the salt marshes of Massachusetts and Louisiana (you can see pictures of them below). Just like on the beach, if you pick up seaweed in the marsh, hundreds of little crustaceans will flip and spring until they can hide in the grass. Not much of a terror. In terms of diet, these amphipods are more interested in a rotting veggie burger than a hunk of a marine-biologist.   

Then why did they attack the young man’s legs in Australia? We’re not sure. Amphipods can bite humans – sometimes beach runners will have a bite or two – but they have rarely caused such damage. The best guess is that the amphipods were in a feeding frenzy and the young man’s legs happened to get in the way.

While I’ve been playful with this story, as a father, I too would have been worried. As a marine biologist, I am curious. It shows that we still have a lot to learn. The next time I pick up an amphipod I will check to see if it’s wearing a handkerchief and holding a knife and fork.  

 

 

P.S. Now that we have flesh-eating amphipods in the news, soon I will write about zombie amphipods. Stay tuned. Duh-nuh…

P.P.S. If you enjoyed this article then please post it on Facebook, Twitter, or your favorite social media. And don’t forget to follow me. 

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Why did the fiddler cross the road?

Williamsburg, Virginia

Fiddler crossing, Uca minax, red-jointed fiddler (28) - Copy
I was riding my bike in my neighborhood when I saw a fiddler crab skitter across the blacktop. I stopped immediately to catch it because when it comes to marine life, I’m like a dog who can’t help but chase the rabbit. Plus, I don’t often see marine life skittering across blacktop in the middle of the day in June. I caught it. It was a red-jointed fiddler crab (this post reminds me that I need to write a post about fiddler crabs, but that’s for later).

Fiddler crossing, Uca minax, red-jointed fiddler (11) - Copy
A male red-jointed fiddler crab, Uca minax

Fiddler crabs live in burrows in beaches, salt marshes, and mangroves, not roads. But it’s not unusual to see fiddlers on roads that have been built right through the place where they live. In parts of coastal Virginia where the roads cut through the marsh, you can see herds of fiddler crabs roaming the road like cattle. The question is, why do fiddler crabs cross the road? One reason is that the road used to be a marsh where fiddlers grazed. Now they may cross the road for better pastures. Build a road through my house and I’m liable to wander onto it on my way to the kitchen for an avocado. But mind your honking in my house, I have a 2-year-old trying to sleep and an anxious cat who needs therapy. 

Fiddler crossing, Uca minax, red-jointed fiddler (24)
A lady fiddler has eggs underneath her (up to 10’s of thousands) 

To-get-to-the-otherside-for-a-snack is a fine answer for why fiddlers cross the road when the road is in their backyard. But the road I found the crab on today was at least 100 feet uphill from the marsh with a forest in between. I found seven wandering fiddlers total. What drives a fiddler to hike through the woods and then onto the highway? Fiddler crabs eat algae and little bits of dead plant found in the soil. I don’t think blacktop or frontyards or woodlands offer much forage for a fiddler.

Fiddler crossing, Uca minax, red-jointed fiddler (17)
A male fiddler crab challenges a baby pine tree. Males. Yeash. Am I right ladies?

My working hypothesis is that because we’ve had so much rain that it made the water too fresh for these marine crabs. But that hypothesis was shot down when I found a fine fiddler party in the marsh. My best guess is that because the temperatures were low and the road and forest were damp, they were simply brave crabs exploring new lands. There have been a lot of For Sale signs around. Now might be a good time to move.

 

Fiddler crossing, Uca minax, red-jointed fiddler (16)
Male fiddler crab doing his best, “I’m on Saturn” impression

In truth, I don’t really know why these crabs traveled so far. As I sit here daydreaming in rain, the why of it leaves my mind, like the crabs, to wander.

P.S. If you enjoy these posts, and of course you do, then please sign up for email updates! I don’t post often. Too much time chasing crabs.

Fiddler crossing, Uca minax, red-jointed fiddler (10)

Fiddler crossing, Uca minax, red-jointed fiddler (13)
Without thumbs, hitchhiking crab can’t get a ride
Fiddler crossing, Uca minax, red-jointed fiddler (15)
Soccer crab has got the sideways moves for goalie, but he just can’t find the net.


Snake bush

Jamestown, Virginia

I went down to the river today and found at least three* serpentine sunbathers draped across the branches of this bush. My best guess is that they were brown watersnakes, Nerodia taxispilota, based on my visit to the Virginia Herpetological Society’s awesome site. Can you find the three reptilian sunsoakers? 

3 water snakes - Jamestowne, VAI’ll update the post later in the week with the answers. 

*I say “at least three” because there could be more that I didn’t find.

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. 

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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.

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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.

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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.

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*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.