All posts by David S Johnson

Need a date? Just wave.

Here is a great video put together by the New York Times explaining how female fiddler crabs not only prefer males with larger claws, but also with claws that wave faster. This is based on work by Australian researchers who used robot claws to wave faster or slower. Waving is part of fiddler-crab courtship. So remember, the next time you’re in a bar or the grocery store and you see someone you’d like to court, wave your little claw off!

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Blind daffodils and a splat of moss

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Snowdrops with raindrops

It rained all day yesterday and the snowdrops are now dappled with raindrops. A splat of moss that has made its home on a slate of stone is without shame and has flashed its naked gametophytes (gam-meat-o-fights), sporophytes (spore-o-fights), and sporangium (spore-anj-e-um) for anyone to see. Don’t worry if you don’t understand the sex life of the mosses. I don’t either. So long as the mosses have it figured out, we shouldn’t worry. Throughout the neighborhood, the daffodils have put up their green swords ready to charge into spring. But they charge blindly because they yet to reveal their crowned heads. But I can’t criticize, when I blindly stuck my head out this morning I had to retreat and put on a knit hat. Spring may be coming, but it is winter that is here. 

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A splat of moss on a stone of slate
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Blind daffodils

*****If you enjoyed this post then please consider donating to your local food bank. Even if you didn’t enjoy it, consider donating anyway.

Wild snails of the flowerbed

Thanksgiving Day,
Williamsburg, Virginia

It’s 3:00 P.M. on Thanksgiving Day and I’m bored and slightly cold. We will eat at 4:30 P.M. I’m not sure what to do with myself so I’m sitting behind the couch using the box for the cat’s scratching pad as a mouse pad and writing a blog while my mother reads and my mother-in-law vacuums.

What to write about? Snails. A good go-to for me.

Two days ago when it was 60 F, I laid on the red-brick patio and watch a snail that I had dislodged from a planter that I moved. It had been hiding under there, probably to overwinter. But I brought it out into the open. It was nice just to watch the snail without any sort of agenda. So often in my science I’m making observations so I can scribble them down, analyze them, write a grant, get rejected by the grant, write another grant and finally give up and move on to another subject. Just like a football coach who points out the errors in the defensive line of a team he doesn’t coach, I can’t help but analyze Nature instead of just enjoying the game. My head instead asks, What species is it? How old was it? How big? How many are in the yard? What predators does it fear? But I let myself relax. I watched and I enjoyed. I watched the slide of its stomach-foot over the electric green moss that cushions the red bricks. While I didn’t take any data, I did take pictures.

And what will this snail eat for it’s Thanksgiving meal? It’s 43 F here today so it may be too cold for it to eat, but if it does feast, it will be on rotting leaves, mushrooms, and if it finds its way to my compost pile – the carcass of a Halloween pumpkin. Some meals don’t require basting. 

By the way, if you haven’t read the beautiful book The Sound of Wild Snail Eating you should. It’s a wonderfully written book about a bed-ridden woman who befriends a woodland snail.

Happy gobbling. Backyard snail (6)

Backyard snail (5)

Backyard snail (2)

Backyard snail (1)

And the spider saltated down beside her

Williamsburg, Virginia

Instead of keeping an eye on my 2-year-old son* at the playground, I watched a jumping spider walk on and jump between a pair of abandoned sandals. It was as though the spider was testing the springiness of insoles as potential launchpads for catching flies. I tried to take his picture, but the spider was shy and launched himself into the grass.

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Not the jumping spider I saw, but another found in Virginia. Jumping spiders are harmless to humans. They were also voted Most Adorable in their class (it’s their big eyes). Photo copyright Kim Hosen and courtesy of http://www.pwconserve.org/wildlife/insects/spiders/palejumpingspider.html

Jumping spiders are in the family Salticidae (sal-tis-uh-day), which sounds like a rejected day of the week. The name refers to the spider’s leaping skills. The movements of animals that jump are described as saltatorial (animals that dig – like moles – are fossorial). The word ‘saltate’ come from the Latin, saltus, which means to leap or dance. Do you saltate up and down with joy when you find one more M&M in the bag when thought they were all gone? I do, too. The saltatorial grasshopper, frog, kangaroo and jumping spider all jump and dance in the grass, the pond, the Australian outback, and on the playground sandal.

What happened to the woman who was in the sandals? Maybe a spider sat down beside her and she jumped clean out of them. And given that many of us saltate when we see a spider – regardless if it jumps or not – there may be a spider writing a blog somewhere about the ‘jumping human’ and its saltations.

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The spider sandals


*My son is fairly careful and let’s off an alarm that brings judging parents from miles around when he’s anywhere close to danger. He also still requires a hand to hold when he saltates (no M&M’s required).

Marsh beauties

It has been a busy summer for my lab. Here is a taste of the beauty that I get to see when I sample the marsh. Most of the pictures below are from the Great Marsh in Massachusetts unless stated otherwise. What a gorgeous ecosystem sparkling with life.

Sea Lavender, Limonium, Rowley, Massachusetts (5)
Sea lavender looking lovely (Limonium sp.)

Sea Lavender, Limonium, Rowley, Massachusetts (6)

Sea Lavender, Limonium, Rowley

Red mite party, West - May 2017 (3)
A shock of red mites meet on the marsh
Snail and eggs, Cushmans Landing (1)
I think these are fish eggs, not snail eggs (Virginia marsh).

 

Spartina patens - Rowley, Massachusetts
Salt hay (Spartina patens) in the sunset

 

Rowley House Sunrise, Rowley, Massachusetts
Good early morning Rowley River. I’m going back to bed. 
Barnacles on Spartina
Barnacles posing as dirt on the grass (Virginia marsh)

Plant bug on fiddler crab, Rowley, Massachusetts

A plant bug sits atop a muddy fiddler crab (female, Uca pugnax)

Crabs with Jeff Shields (12)
What the electric insides of a fiddler crab looks like (Uca pugnax)

 

 

 

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…

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