I’ve always been familiar with this poem, but it wasn’t until I went searching for a Burdock den that I realized this plant is everywhere! It grows along roadsides and old fence lines, in fields and ditches, along stream banks and in all neglected areas. It spreads like wildfire, but why did Emily Dickinson call a patch of Burdock a “den” I wondered.
In The Ugly Duckling, Hans Christian Andersen says, “In a sunny spot stood a pleasant old farmhouse, circled all about with deed canals; and from the walls down to the water’s edge grew great burdocks, so high that under the tallest of them a little child might stand upright.” Since it grows in full or partial shade and can reach a height of 6 feet, I suppose a large concentration of Burdock could be viewed as a “den” and a place to be avoided.
Many animals such as birds and mice on the lookout for seeds to eat are impaled on the sharp burs. The more they struggle, the more burs they touch and the tighter they are held.
A Burdock seed head is covered with small, Velcro-like devices that easily fasten onto anything or anybody that passes. In this way the seeds travel to a new location that is less crowded — an ingenious method of seed dispersal!
Our Nature Study class met at Steele Creek Park in Bristol, TN, which has a variety of habitats for observing seed dispersal.
Also known as Snapweed or Touch-Me-Not, the Jewelweed is a delicate little plant that grows in wet places. The small, trumpet-shaped flowers themselves are petite and intricately lovely. But our interest here lies in the seed pods, which grow right alongside the blossoms but are a completely separate appendage. If the pods are touched in the Autumn when they are ripe, they explode with a tiny ferocity that is startling! Once I happened to brush by a large patch of jewelweed bushes and could hear the seeds popping all around! In this way, the parent plant sends her “children” into the world where they have a better chance of starting life in bright sunlight and nutritious soil. The sap of this plant is a folk remedy for poison ivy. You can find soaps, salves and sprays online or at your local health food store.
Another plant which is known for projectile seed dispersal is Witch Hazel. This helpful plant blossoms in the dead of winter and 8 months later the seed pods split apart explosively and send the glossy black seeds into the air — sometimes reaching 33 feet from the parent plant! The Native American Mohegans reportedly introduced English settlers to using the Y-shaped witch hazel sticks for dowsing, an ancient method for finding underground water. The name “witch hazel” is believed to have come from the Middle English “wicke” for “lively” and “wych,” an old Anglo-Saxon word for “bend.” The Osage used witch hazel bark to treat skin ulcers and sores, the Potawatomi steamed twigs over hot rocks in their sweat lodges to soothe sore muscles, and the Iroquoi brewed a tea to treat dysentery, colds, and coughs.
Children have a special fondness for another plant in this projectile category: Oxalis (known locally as Wood Sorrel or Sourgrass). This low-growing plant has yellow flowers and sour, Shamrock-shaped leaves which children (and some adults) love to chew.
The seed pods, which grow alongside the blossoms, look like little candelabra and when they suddenly split and curl (like Jewelweed) their seeds are projected quite a distance.
Other plants shoot their seeds — the wild geranium and certain violets, for example. Even some of our garden peas bean varieties scatter their seeds by curling in a spiral and dispersing their seeds in a circular pattern — the better to ensure their nutrition and survival.
We began our ramble beside the creek in search of Jewelweed, but the large patch I had observed a few weeks earlier was no longer in evidence. (However, on our way home my son and I spied a large patch and spent a very pleasant 20 minutes “helping” disperse some seeds.) Next we all headed over to the large wildflower habitat and although no Witch Hazel was located we did discover (and sample) plenty of Oxalis leaves. We observed several other fascinating and beautiful specimens:
Saw seeds caught in a spider’s web…..
…..found a growth of Staghorn Sumac so dense it formed a den of sorts where several animals had obviously sheltered…..
…..were captivated by the morning glory’s beauty…..
…..discovered buckeyes floating in the creek……
…..caught a crawdad…..
…..unearthed a giant fungus…..
…..found a branch covered with insect hieroglyphics…..
…..spied a bright green passion flower fruit…..
…..and a praying mantis!
Of course, everyone enjoyed capturing observations in their nature journals!
Taking a walk along the banks of a stream or drainage ditch is your best bet for finding Jewelweed. Remember, the blossoms and seed pods grow concurrently and you may need to revisit the Jewelweed patch to check for seed pod ripening.
Witch Hazel is a bit harder to locate, but since the flower blooms in winter this is a good time for locating the plant. You’ll find them in mostly in open woods.
Oxalis can be found wherever there is grass growing, especially along the border between a grassy area and an overgrown field. Look for their tiny yellow flowers and candelabra seed pods growing concurrently.
What did you notice? What do you wonder? What does it remind you of? What mechanism does the plant use to disperse its seeds? Does the seed pod curl up or form a spiral after dispersal? How might this help scatter the seeds far away from the parent plant? After finding several Buckeyes, one of our students wondered if Chestnuts and Buckeyes are one in the same, and launched into a bit of on-site research with a field guide. You never know what questions will arise when you take the time to observe and wonder!
From the bud comes the flowers, From the flower comes the berries, From the berries feeds does the bird, From the bird seeds are spread, From the seeds new trees grow, From the trees buds sprout into life, From life comes more life ad finem.
In this neck of the woods, some folks eat “poke salat” in the Spring — basically the stir-fried greens of the wild pokeweed plant. However, because this plant is contains tannins and is quite toxic to humans, the leaves must be repeatedly boiled and rinsed before ingestion. If you’re unfortunate enough to eat any part of the pokeweed without taking adequate cautionary measures, the old-fashioned remedy is to drink lots of vinegar and eat a pound of lard! The pokeweed gets its name from the Native American word “puccoon” which means a plant used for staining or dyeing. They also used it as a laxative and to induce vomiting! Yet certain animals (birds, white-footed mouse, oppossum, red fox and stinkbugs — yes, stinkbugs) have no such limitation and can feast on poke to their hearts’ content.
The Pokeweed, sometimes called Pokeberry or Inkberry, is native to eastern North America. From July -September, the plant blossoms. Those white things you see are not petals but sepals which will cradle the fruit in Autumn.
When Autumn arrives the green stems and sepals turn a bright pinkish-purple, and the dark purple berries contains large seeds that are glossy and black. Animals eat the berries and after walking or flying around for a while they expel them as waste, thus scattering the seeds far from the parent plant.
Pokeweed dies to the ground in the winter and sends up new shoots each spring.
Here’s a great little video on all things pokeweed: https://www.youtube.com/watch?v=tQuoErwKzUY
You can make a lovely ink out of pokeberries. Here’s the recipe: http://www.nytimes.com/slideshow/2015/09/17/t-magazine/pokeberry-ink/s/17tmag-pokeberry-slide-2WP8.html
Pokeberries can also be used to dye yarn, fabric, lace, Easter eggs — you name it! Here’s that recipe: http://botanicalcolors.com/2011/10/30/pokeberry-dyeing/
As always, after a hike we take time to record our observations — either by sketching or painting, in narrative form, or even in poetry.
And even the moms get in on the act! (Did she plan to wear a pokeberry-colored tee?)
They sail away on an autumn day when windy is the weather.
We’ve all seen milkweed “fairies” floating past us on an autumn day, but have you ever looked inside the pod from which those “fairies” came? It’s a pretty amazing place! Milkweed plants grow along roadways, in fields, along fencerows — anyplace there’s plenty of sun. Milkweeds have beautiful pink flowers which are a favorite nectar-gathering source for many insects — most notably the Monarch Butterfly.
After the blossoms have faded, a long green seed pod forms which is visited by several insects searching for food. The Milkweed Bugs (both nymphs and adults) feed on the seeds of the milkweed plant.
As the seed pod ripens, it turns a brownish-gray color. If you look inside, you’ll find all the little milkweed seeds attached to their plumes. They’re all attached to a central core, facing in one direction, and look almost like a pine cone with a white tail.
Each milkweed seed is an akene, which simply means one seed with a tight envelope about it. When the wind catches the its plume, each akene goes sailing to a new location — sometimes very far away from the parent plant. And if the milkweed akene lands in the water it’s no problem at all — the rim of the akene is like a life preserver which allows the seed to float until it reaches its destination.
How do you think the Milkweed got its name? Is it because cows who eat milkweed give sweet milk or because its flowers are white? No, it’s because of the milky substance that leaks out when the plant’s stem is broken or gashed. This milky substance is like liquid rubber and when it hardens is so gummy it can seal the wound from which it came. In fact, the Shoshone tribe collected the plant’s “milk” and made chewing gum of it! (PLEASE DO NOT TRY THIS YOURSELF! MILKWEED “MILK” CONTAINS POISONS!) Native Americans also used it in poultices to draw out poison or infection from wounds.
One more very cool thing about milkweeds — how they are pollinated. The flowers are uniquely adapted for insect pollination, having waxy pollen in tiny wishbone-shaped structures which hook onto an insect’s leg but come off when transferred to the flower of a different plant. Here’s an amazing photo from a great nature blog, Nadia’s Backyard, in which you can actually see the tiny “wishbone” attached to a bee’s leg. You can read the whole post here: http://nadiasyard.com/our-native-plants/milkweed-common-asclepias-syriaca-uncommon-versatility/
On our excursions, we always try to take time to record our observations.
Some choose to sketch while others may paint what they’ve seen.
Still others prefer to keep a written record of their findings.
And then there are the poets among us! At our very first class, one of the students asked if he could record his observations in poetry. I answered that not only could he do so, but if he did I would do a dance of joy! So Alex shared a short poem which ended, “……and now Mrs. Hissong has to dance!” And so I did — right there in the meadow! Here are his observations on the milkweed:
Gaze upon the Monarch’s chrysalis. Behold. Admire its colors. The Jade flecks and the Gold.
Watch the caterpillar change being, bursting out of the chrysalis and taking wing.
this new creature, this butterfly unfolding his wings and flying high,
his glamorous suit of orange and black warning predators not to attack,
flying up north on this incredible migration then going to Mexico on vacation.
Steele Creek Park in Bristol, TN, was the site of this week’s nature study class. Hoping to surprise some turtles basking on a large fallen tree in the shallows, we began our time together by creeping quietly down to the lake. Our stealth was rewarded by finding several specimens of differing size bathing in the afternoon sun. After sharing some extremely corny “turtle jokes” (Why did the turtle cross the road? To get to the Shell station. What do you get when you cross a turtle with a porcupine? A slow poke.) we entered the Nature Center where several species of turtles are kept in huge tanks. After Jeremy Stout, manager of the Nature Center, fed the huge snapping turtle so we could watch it sneak up on its prey and POUNCE, the students each chose which species they’d most like to see “up close and personal” and I asked some questions to start their observations.
— Describe the turtle’s skin (what little you can see outside the shell). (Reptiles have dry, scaly skin (herpetology is the study of scaly things) and amphibians have smooth skin.)
— Compare the upper (carapace) shell with the lower (plastron). How are they shaped differently? (Most turtles have a curved carapace but in some species it’s flat.) Are the shells of different colors? Why might the carapace be darker and the plastron be lighter? (For purposes of camouflage. Predators or prey looking UP from the bottom of the body of water would see a light color like the sky, while those looking DOWN from above would see a darker color like the substrate.)
— Make a quick sketch of the upper and lower shell showing the shape of the plates that compose them. Where are the two grown together? (The carapace is grown fast to the backbone of the animal, and plastron to the breastbone.)
— Describe the turtle’s eyes. Does the turtle have eyelids? (Turtles’ eyes have nictitating membranes (“nictare” = Latin “to blink”) — a transparent or translucent third eyelid that can be drawn across the eye for protection and to moisten it while maintaining visibility. The turtle’s nictitating membrane comes up from below and completely covers the eye.)
— Do turtles have ears? (Turtles have 3 ears — 2 located on the sides of their head (small holes) and one on their nose. Turtles have “inner ear” mechanisms that other animals have. The outer ear gathers vibrations which makes the sound louder. While turtles can’t hear airborne sounds, they do sense and interpret vibrations within their environments. Meanwhile, the organs in a turtle’s ears do help them feel changes in water pressure that can warn them of the presence of predators.)
— Describe the turtle’s mouth. Are there any teeth? How does the turtle bite off its food? (The turtle has no teeth but strong, cutting jaws called a “beak.”) Describe the movement of the turtle’s throat. What is the cause of this constant pulsation? (The turtle is swallowing air for breathing.)
— Describe the shape of the legs. How many claws on the front feet? (5) On the back? (4) Are any of the toes webbed? On which feet are the webbed toes? Why should they be webbed? (To enable the turtle to swim faster.) Describe the way a turtle swims. Which feet do you think the turtle uses as oars? (Those which are webbed.)
I shared with the students that like all reptiles and amphibians, turtles are ectothermic (cold-blooded) animals, relying on their environment for warmth. Unlike some animals which hibernate (one lengthy period of inactivity) in winter, cold-blooded animals brumate (periodic awakening and temporary resumption of activity and feeding). In winter, water turtles may bury themselves in the ooze at the bottom of ponds and streams. Land turtles dig themselves into the earth for several short winter naps.
THE TURTLE SHELL
The shell is composed of hard, bone plates covered by scutes. The scutes are made of keratin, the primary substance in hair, nails and hooves. Pigments may form intricate designs and bright patterns in some species. Although the scutes form the familiar outer layer of the shell, it is the bony layer underneath which actually provides the shape, support and protective qualities of the turtle shell.
The vertebrae of the neck and tail are small, allowing for a high degree of flexibility, while the vertebrae of the central portion of the vertebral column are enormously elongated and inflexible, fused with the bony layer of the shell, acting as a support for the carapace. If the outer keratin is breached by infection or injury, the turtle can lose its protection and infection can proceed into the bony layer and the body cavity, threatening the turtle’s life.
RIDDLE: Alive without breath, as cold as death, clad in mail never clinking, never thirsty, ever drinking. (A FISH)
Bilbo Baggins didn’t stump Gollum with that riddle deep under the Misty Mountains, and I couldn’t stump my students with it either! To focus on fish, our nature study class met beside Little Limestone Creek at Mill Spring Park in beautiful, historic Jonesborough, Tennessee. It was a warm, overcast day, but the thunderstorms held off and at least the moms were able to stay relatively dry. The kids were another story — as you will see! We started off by collecting specimens from the creek in large, clear containers: Minnows, aquatic insects and even a crayfish. We brought them to the gazebo, spread out the quilts, got out our hand lenses, and sat down for a good, close look.
How many fins has the fish?
Are the fins constantly moving? Do they move together or alternately? How is each fin used? How are they used when the fish swims backward? What are the fins doing when the fish is at rest?
Is the tail square, rounded, or notched?
What covers the fish? Are the scales large or small? In what direction do they seem to overlap? Of what use to the fish is this scaly covering?
Can you find a long line running down the fish’s side? That’s called the lateral line.
Describe the pupil and iris of the fish’s eyes. Can the fish see in all directions? Does it do so by moving its eye or its body? Does the fish wink? Can you see that the eye is spherical?
Can you see the nostrils? Is there a little wart-like sac connected to the nostril?
What sort of teeth does the fish have?
Does the gill cover move with the opening of the mouth?
The fish usually has 7 fins, which play a different role in the fish’s movements:
Dorsal Fin – like a fan, protects the fish against rolling and assists in sudden turns and stops
Tail (Caudal) Fin — propels the body through the water like a scull
Anal Fin – used to keep the fish stable in the water
Ventral (Pelvic) Fins (2) – The pelvic fins assist the fish in going up or down through the water, turning sharply, and stopping quickly
Pectoral Fins (2) – help fish rise or sink in the water
Sight — The eyes of fish have no eyelid. Fish are nearsighted because the lens is spherical which enables the fish to see underwater.
Smell — The fish’s sense of smell is located in a little sac to which the nostril leads, but the nostrils have no connection whatever with breathing.
Taste — The tongue of the fish is very bony or gristly and immovable, and they have very little sense of taste. A fish’s teeth can be located on the jaws, inside the mouth, on the tongue and even in the throat! Fish without teeth expand their jaws and create a huge vacuum so they can literally inhale their food 😉 Check this out!
Hearing — Fish have poor hearing. They have only an inner ear and it has no exterior outlet. Instead, it is found inside the fish’s head behind the eye. Since fish have approximately the same density as water, sound passes right through their bodies. That doesn’t mean they don’t respond to auditory stimuli, though. Recent research indicates that fish may exhibit the Lombard Effect when exposed to loud or unfamiliar sounds. (The Lombard Effect is the involuntary tendency of speakers to increase their vocal effort when speaking in loud noise to enhance the audibility of their voices.) You read that right: Fish communicate out loud. Here’s a short video of minnows “growling” and “knocking”:
Touch – A fish’s “lateral line” consists of different scales that extend along the sides of the body containing small tubes connecting with nerves; it is used to detect motion and vibration in the water – like touch at a distance. This lateral line is especially important when fish need to gather and/or travel in “schools” because it allows each fish to sense the motions of its neighbors.
The shape, number and position of a fish’s teeth vary according to the food habits of the fish. Some have blunt teeth suitable for crushing shells; others have sharp teeth with serrated edges for harvesting vegetables, while some have incisor-like teeth who feed on crabs and snails. In some species there are several types of teeth, while others (goldfish and minnows) have no teeth at all. Fish teeth can be on the jaws but also in the roof of the mouth, on the tongue and in the throat.
The covering of fishes varies: Some have scales, others have a smooth skin. All fish are covered with a slimy substance which somewhat reduces friction as they swim through the water.
In order to understand how a fish breathes, we must examine its gills. They are filled with tiny blood vessels, and as the water passes over them, the impurities of the blood pass out through the thin skin of the gills and the life-giving oxygen passes in. A fish constantly opens and closes its mouth to draw water into the throat and force it out over the gills – the act of breathing. Fish can’t make use of the air unless it contains enough oxygen, so it’s important that the water they’re in have enough surface area (definitely NOT like Dr. Seuss’s McElligot’s Pool!)
I’ve been so pleased with the progress of our students in just a few short weeks! They’re paying closer attention and noticing so much more. Maybe these nature observation prompts we’ve been using (from John Muir Laws http://www.johnmuirlaws.com/natural-history/deep-observation) have helped played a role. For each journal entry they are asked to complete these thoughts:
I notice ______________. (Example: …this flower has five petals, red anthers and serrated leaves.) Requires close attention.
I wonder _____________. (Example: …how it disperses its seeds?) You can help them follow up with this.
It reminds me of ________. (Example: …the wild strawberries we saw growing by our boat dock.) This will eventually lead to classifying specimens by leaf shape, color, and other physical characteristics. It can also help us make connections to previous learning — a poem, story, work of art.
My 12yo son’s journal entry this week included a sketch and these observations:
I notice that this tree has shallow roots and the roots are in the creek.
I wonder why the bark is in vertical patterns? Maybe so rain water will run down to the roots?
It reminds me of elves. ( He’s a huge Lord of the Rings fan!)
It’s so important to take a moment to make a short sketch or note a small detail while you’re in the field. If you goal is a lovely nature journal page you can always flesh things out in living color later. But that tinge of blue on the tip of a wing or the dew drops collecting on an upturned leaf — those lovely bits may be forgotten if you don’t note them as you see/hear/smell them.
I’ll leave you with image of a single Cardinal Flower (Lobelia cardinalis) we found growing by the creek and a blue darner damselfly — so very lovely! (All photos in this post were taken by the lovely and talented Beth Waugh.)
Crayfish and salamanders and Hickory Horned Devils — OH MY! What a time we had today at our weekly Nature Study class! We visited a mountain stream at the foot of Bays Mountain in Kingsport, Tennessee to learn about crayfish. But we learned about so. much. more.
The greatest diversity of crayfish species is found in southeastern North America, especially Appalachia (that’s us), with over 330 species.
Crayfish are detritivores (they eat detritus = decomposing plant and animal parts) but they also eat living plants and animals such as worms and insects. Raccoons, snakes, opossums and muskrats are the crayfish’s most dangerous predators.
The crayfish breathe through feather-like gills and tend to inhabit water bodies that don’t freeze all the way through to the bottom. Some species are found in brooks and streams where there is fresh water running, while others thrive in ponds, swamps and ditches. Most crayfish cannot tolerate polluted water, so if they are present the water is probably pretty clean.
Crayfish burrow during the late summer, and spend most of the fall and winter underground in water-filled tunnels. Everywhere you see a crawfish chimney, there is a crawfish living in a burrow underneath. Their tunnels may extend down into the earth 3 feet or more and are full of water. Sometimes the color and texture of the chimney mud is different at different levels of the chimney. Why might this be? This is a sign that there are different types of soil layers below the surface, and the crayfish has burrowed through several layers.
During droughts, crayfish routinely plug the openings of their burrows with mud. As the water table drops, or when the temperature drops, the animal moves further down to warmer water levels. Over time, oxygen may be depleted in the burrow water. When this happens, the crayfish may position itself just above the water, thus keeping the gills wet and absorbing oxygen from the air in the burrow.
Crayfish also lay eggs in their burrows. After they mate in open water, (the male depositing sperm into a special sac on the female’s abdomen) the female (and sometimes the male as well) will dig a burrow where the female will lay the eggs, fertilize them with the stored sperm, and hold them attached to little appendages under the tail called swimmerets.
Once the eggs are laid, the male typically stays near the entrance and the female remains deeper in the burrow. As long as oxygen levels in the burrow water are high, the female keeps the eggs under water and swishes them back and forth to ensure aeration (air circulation). As the oxygen drops, the female keeps the eggs moist, but gets them out of the water, thus allowing them to absorb oxygen from the air. https://www.youtube.com/watch?v=XHCWiISnu_4
The eggs usually hatch in the burrows and begin to grow. Since there is a restricted amount of food available in the burrow, the babies eat infertile eggs and the bodies of dead babies. They will even kill each other to survive.
After the hatching, with her brood still attached, the female emerges from the burrow to find food. Once she is in open water, the hatchlings detach from their mother and begin living independently.
A young crayfish molts 11 times before becoming an adult. This takes about a year. They will live another year to mate and produce young. In this video, the carapace (shell) completely detaches about 5 minutes in: https://www.youtube.com/watch?v=mF6NgMBcNCM
In 2011 a new species of giant crayfish was discovered in Shoal Creek, a tributary of the Tennessee River. “A new species of giant crayfish [has] literally crawled out from under a rock in Tennessee, proving that large new species of animals can be found in highly populated and well-explored places,” Reuters reported. Aquatic biologists had been studying life in that little waterway for decades, but it appears these crayfish are not common (only 5 have ever been caught) and their preference for living under large rocks in deep water may have made them easy to overlook, especially in times of high water. After DNA testing and studying a ridge and unique spine between the crayfish’s eyes, the biologists knew they were looking at something entirely new, and named it Barbicambarus simmonsi (after TVA scientist Jeffrey Simmons — the guy who first spotted this giant).
We spread out along the length of the creek. We haven’t had much rain lately so the water was low. Within 15 minutes the class had collected about 30 samples of crayfish at all different stages of development and a couple of baby salamanders.
Then a shout went up: Look what was found crawling along on the creek bank!
It’s a Hickory Horned Devil Caterpillar that will dig a hole in the ground and after pupating through two winters will emerge as a beautiful, huge Royal Walnut Moth!
And if that’s not enough, look who else came to call:
Did you know there are JELLYFISH in Bays Mountain Lake? Today our Nature Study class visited Bays Mountain in Kingsport, Tennessee, to learn about freshwater jellyfish. We even convinced a good-natured naturalist to take us on a barge ride around the lake to investigate! How in the world did they get there, you ask? Read on…..
Although we call them freshwater jellyfish, some argue that the Craspedacusta sowerbii is more closely related to the Hydra family than a “true” jellyfish, so many naturalists and scientists just call them Freshwater Jellies. The main difference between jellies and “true” jellyfish is the presence of a velum — a think circular membrane around the cap that helps propel the jelly forward. Freshwater jellies are transparent, gelatinous, umbrella-shaped creatures with a whorl of stringy tentacles around the edge of their bodies. Microscopic barbs called nematocysts run along the tentacles to help capture food and protect the jelly from predators. Luckily for us, jellies are quite small — adults are the size of a quarter — and their stings can’t even penetrate our skin.
Jellies have no head or skeleton, and contain no special organs for respiration or excretion. Their bodies are 99% water. Their large, flat reproductive organs are the only parts of the freshwater jelly that are not translucent, and this makes them easy to spot on sunny days when they tend to surface in large groups called “blooms.” They eat tiny microscopic animals called zooplankton that are found floating in the water. When they come into contact with prey, stinging cells in the jelly’s tentacles paralyze the organisms and then sway about moving the captured prey its mouth which is in the middle of the underside. The bell (body or umbrella part) of the jelly goes through several contractions to move the prey into the mouth and digestive cavity. The primary predators of freshwater jellies are crayfish and turtles.
Freshwater jellies have a multi-stage life cycle that includes two forms — the polyp and the medusa. The medusa form is more familiar, and it is during this adult stage that jellies reproduce sexually and fertilized eggs that develop into larvae detach from the medusa and drift away. This larvae form, now called polyps, will also reproduce — but it will do so asexually by dividing from one another. This is called “budding,” and the buds will then develop into adult medusa and the cycle repeats. During the winter the polyps contract and become “resting bodies” that are capable of surviving the cold temperatures. They are circular and fairly flat with no hooks or burrs, but there does seem to be some adhesive property which allows them to become attached to surfaces. Some scientists believe that the resting bodies are one way in which the jellyfish are transported — on aquatic plants, by aquatic animals, or on the feet of birds. When conditions become favorable and temperatures rise, the resting bodies develop into polyps and the life cycle continues.
Freshwater jellyfish can be found all over the world, but are not native to the United States. There are two schools of thought on their origins. Some believe they originated in the upper Yangtze River basin in China, and were first observed in the western world in water lily ponds in London’s Regents Park in the late 1800’s — having presumably arrived as polyps on the plants imported from China. Others say they originated in South America and made their way to the US in the bilge water of ships. However they got here, jellies spread rapidly and are now found all over the US in every state except North and South Dakota, Montana, Wyoming, Alaska and Hawaii. Why might this be? (Too cold in most of these places, and Hawaii just doesn’t have enough fresh water)
I asked the class how jellies might have gotten into Bays Mountain Lake. They can enter a body of water in many ways — in the water of bait buckets, through flooding from another site, on boat propellers. But we decided the most probable answer may be that they were carried in on the feet of migrating birds during the “resting body” stage of development.
The appearance of jellies is sporadic and unpredictable. Often they will appear in a body of water in large numbers even though they were never reported there before. The following year they may be absent and may not reappear for several years. It’s also possible for jellies to appear once and never appear in that body of water again. In some lakes they appear almost every single year. Why this difference? What triggers the appearance of medusa in certain places and at certain times? Temperature seems to play some role in triggering the medusa stage, which is why there is a freshwater jellyfish season, typically from August to September when water temperatures are highest.
Searching for jellyfish can be a fruitless venture, but the best time of year is NOW, and they are most likely to be found in calm bodies of water, which they prefer to rocky, fast-flowing rivers and streams. After walking across the dam and peering into the deepest part of the lake (which is what jellies usually prefer) we were unable to locate a single specimen. So Ranger Bob (sans the ponytail and facial hair he has sported for years) graciously treated us to a long ride on the barge so we could explore further. While we didn’t encounter any jellies (none of the naturalists we spoke with have seen them this year), we did see beaver dams, water lilies and lots of dragonflies. Definitely time well spent!
What an adventure we had today! We started out in a sunny field full of wildflowers and grasshoppers and ended up soaked to the skin but oh-so-joyful! Our Nature Study class met beside a meandering stream at a friend’s farm to learn about an amazing aquatic insect: The Water Strider.
Also known as “Jesus Bugs,” water striders literally walk on water! They use something called the “surface tension” of the water to their advantage. Water molecules are attracted to each other and like to stay together, especially on the surface where there is only air above. Since there are no water molecules above the surface for them to hold onto, the molecules at the surface cling extra tightly to the molecules beside them and under them — so tight, in fact, that a “skin” seems to form on the surface. Water striders walk on this thin membrane. Here’s a cool slow-motion video of them in action: https://www.youtube.com/watch?v=RphuMEUY3Og
But water striders have another secret for walking on water — their legs! The legs have tiny hairs that repel water and trap air. By repelling water, the tiny insects stand on the water’s surface and the trapped air allows them to float and move easily — almost as if they were skating!
And finally, water striders are very, very lightweight. So much so that they are able to float. Lily pads and twigs float because the water is pushing up on them, but a rock dropped into the water sinks rapidly because it’s so heavy for its size that it overcomes the “push” of the water.
Using a large bowl filled with water, I asked the class to predict from their size, weight and shape whether these items would sink or float: Paper clip, straight pin, bottle cap, coin, cotton ball, rubber band. Only the bottle cap and cotton ball floated (and the cotton ball sank when it finally became saturated).
Using the surface of the water like a trampoline, water striders can jump into the air to avoid predators or catch prey! Jumping requires a large amount of force on the starting surface. Easy enough on terra firma, right? But jumping on water is much more difficult because too much force will break the surface tension. Recently mechanical engineers from Seoul National University have developed a robotic insect that can jump on water, too. Researchers say this technology could someday be used in surveillance missions. Watch! https://www.youtube.com/watch?v=Z83l347rh6E
Water striders can live for many months, and adults can overwinter by crawling inside a plant stem when it gets too cold.
Like all insects, water striders have six legs, and each set has a different use. I asked the students to observe water striders in the stream and try to determine to what use the insects puts each set of legs. (They use their front legs to catch and hold prey, their middle legs to row, and their hind legs to steer.)
If there is time, observe what water striders eat and how they eat it. (Water striders are carnivorous and use their piercing mouth parts to inject a chemical that liquifies the prey’s internal structure so they may then suck them dry. They will eat whatever falls into the water (other insects, worms, honeybees) and use their front legs to find food by sensing ripples made by struggling prey, then grab and hold it while they drink its life juices. Here’s a not-gross video of water striders catching and enjoying a meal: https://www.youtube.com/watch?v=SVoG0Uy_uQ8
Try to determine what preys on water striders. (fish, frogs, salamanders)
A violent thunderstorm with dangerous lightning caused our class to be cut short, but some of the students recorded their observations at home.
A few of us were able to wait out the storm and take a walk into the woods along the creek bank. In addition to a perfectly-preserved, bleached-out cricket exoskeleton, a mystery nut (which turned out to be an immature beechnut) and some nearly translucent, gelatinous, very slimy fungus (maybe snow fungus?), we found the most amazing deep aquamarine bracket fungus growing on a fallen log. What a treasure! It looked just like this (only much more of it):
What has a mouth but does not eat, always murmurs but never talks, has a bed but does not sleep, always runs and never walks? A river, of course!
Today our Nature Study class went snorkeling in the Clinch River near Natural Tunnel State Park in Duffield, Virginia, to get up-close-and-personal with freshwater mussels. Rare and endangered species abound in the Appalachian and Smoky Mountains, and the Clinch River alone sustains 48 imperiled and vulnerable animal species — including 29 varieties of rare freshwater mussels. Because of this concentration of rare animals, the Clinch River has been identified as the number one hotspot in the US for imperiled aquatic species.
The Clinch is home to 45 species of freshwater mussels. Appalachian mussels have terrific names like PURPLE WARTYBACK, SHINY PIGTOE, MONKEYFACE, and PEARLYMUSSEL. Although they all look pretty much alike to the untrained eye, their astonishing diversity is one of the Clinch’s main claims to fame. For a bit of perspective, you’d have to explore every stream in Europe and temperate Asia to find as many species!
Mussels live in a variety of aquatic habitats, but all require areas where the running water has a high oxygen content and supplies a rich food source of organic particles. The constant flow of water also removes waste materials that would be toxic to the mussels, so they are important indicators of water quality. The best substrate (stream bed) for freshwater mussels is a combination of silt, sand, gravel or cobble with little sedimentation.
Adult mussels are sedentary, moving no more than a few feet along the bottoms of the rivers during their entire lifetime, and spending their time flushing water through their bodies and extracting microscopic organisms to eat. The young, however, experience a more adventurous beginning. Each species of mussel has a different species of host fish which it uses as its “nursery.” Female mussels trick fish into coming close by showing off fleshy appendages that act as bait. When a fish swoops close to eat the “bait” the mussel shoots her babies out into the water and they dash to latch onto the fish’s gills where they’ll spend the rest of their early childhood. After several weeks their small shells are formed and they drop off the host fish into the water and float down to the bottom of the stream where they will spend the rest of their lives.
Before the class donned goggles and snorkels, I suggested some things they might look for underwater:
They could assess the turbidity (cloudiness) of the water by checking its color. If the water appeared green or brown, why might that be? It could indicate the presence of algae or sediment. Why might these be present? An algae bloom brought on by favorable weather/water conditions might account for an excessive tint, while sediment could be caused by recent rains, erosion, or even watercraft activity upstream.
They could observe the substrate (bottom of the stream). Were there rocks? Were they clean? Are they covered with silt or sand (upstream disturbance or erosion), slime (algae), or a mixture of both? Were there any plants growing in the water? If so, what kind?
After exploring the underwater habitat, we gathered to share observations and record these in our nature journals. I’ll share some of those entries with you soon, and hopefully some of my students (or their moms) will share comments and photos as well.