WHAT'S A VERNAL POOL? IS IT JUST A MUD PUDDLE?
Most likely, students have never heard of a vernal pool and don't
know the difference between a pond, a pool and a vernal pool. Use
pictures to introduce the animals and plants found near a vernal
pool. Ask students to describe the habitat where these plants and
animals live. Do students know of any vernal pools or wetlands in
their community? What special features do they have? Why are some
vernal pools and wetlands in danger? What effect would the destruction
of a vernal pool or wetland ecosystem have on the larger ecosystem?
POND SCUM GALORE!
Vernal pools are rich in zignema (pond scum), branchinecta linchi
(fairy shrimp), tubolarians (flatworms) and many other plant and
animal creatures. Ask each student to select a vernal pool inhabitant
from the glossary and prepare a "flash card" visual introduction
to this tiny creature. Share these flash cards with the class so
all will have a head start on knowing about the inhabitants of vernal
FAIRY SHRIMP AND INSECT "INTERVIEWS"
Divide students in pairs to role-play an entomologist interviewing
a fairy shrimp and another insect they select. Ask the students
to develop some visuals and props to help both of them act out a
clever interview using some of the following questions: What do
you look like? What kinds of unusual markings do you have? What
are their purposes? What is your behavior like when you are resting,
feeding, working, fighting, etc.? Describe the habitat you live
in and how it helps you live (find shelter, find food, find prey,
avoid predators, etc.) What effect do you have -- both positive
and negative -- on other species and on the human world? Why should
or shouldn't you be stepped on or swatted by the interviewer at
the end of your role-play?
VERNAL POOL MODELS
Ask students to build models to show the changes that occur in vernal
pools throughout the year as the seasons change. Include written
captions to explain the shape and geologic composition of the earth,
the effect of weather, rain and sun on the pools, and the resulting
changes in flora and fauna in the vernal pool ecosystems.
FAIRY SHRIMP IN THE CLASSROOM
Let students play the roles of scientists by growing and observing
fairy shrimp in the classroom "laboratory." Visit www.sacsplash.org/mather/manual.htm
and use Lesson Four for specific instructions and worksheets for
VISIT A VERNAL POOL
Take the opportunity to explore a vernal pool in your community.
Ask students to carefully observe and record the types and numbers
of different plants and animals that they see in the vernal pool.
Back at school, create a mural to show what you saw and learned
about your vernal pool. Conclude by asking students another "V
for Vernal" question: What's the VALUE of a vernal pool?
VERNAL POOLS IN DANGER!
Ask students to investigate the current status of vernal pools in
their state. Explore the role of development, loss of nearby shade
trees, rising water temperatures, increasing evaporation, decreasing
oxygen in the water, less debris for animal cover and protection,
increase in roads and paving, etc., on the health of vernal pools
and wetlands. Write an action plan for preserving these ecosystems
and send it to the local newspaper and local government officials
to publicize this current need.
VIDEO OVERVIEW AND SUGGESTIONS
As you view the video "Fairy Shrimp in Vernal Pools" with
your students, use the timecodes and video transcript as needed
to stop and start the tape, discuss the information and visuals,
and guide your students as they explore this topic. Ask them to
write down any terms that are unfamiliar to them and use the glossary
after the program to define the terms.
Some of our most interesting natural environments can be
found in pretty unlikely places. "You want excitement?
Come and take a look at this!"
Like this one-time cow pasture -- now zoned for industrial
development -- just outside of Medford.
"Boy, look at the density of ostrocods in here!"
The surface is strewn with agates -- the reason this part
of the Rogue Valley is called the Agate Desert. Though these
biologists did not come to look at rocks.
"These bright red ones here are copepods."
The shallow ponds are nothing more than mud puddles to some
people. But the proper name is vernal pools. And Michael Parker,
who teaches at Southern Oregon University, thinks these vernal
pools are some of the most fascinating ecosystems we have.
"This is probably zignema, what people call pond scum."
Yet because the pools seem so common, and maybe since the
creatures in them are so small, these habitats have been largely
ignored and unprotected.
"Oh yeah! I feel like the kid with his first trout!"
But the years of neglect may be ending, because in this
pasture alone, the vernal pools are home to two rare plant
species and a federally listed threatened animal. "Branchinecta
linchi: the common name is the vernal pool fairy shrimp."
"I had a great experience once: These two little kids
came scrambling down off the trail to see what we were looking
at and got in up to their elbows. Mom's on the trail and was
so shocked that they were down there with us, she shouted:
'Get out of there; you're going to get frogs and disease!'
Vernal pools are seasonal. They fill with winter rain, then
come alive with plants and tiny animals in the spring. That's
what the word "vernal" refers to. It's late February
now. By summer, these will be drying up, eventually disappearing,
until the heavy rains return.
For the water to sit like this for months at a time, and not
seep into the ground, also requires a certain geology underneath:
an impervious layer of rock or soil. Nearby table rock is
solid rock, which accounts for the vernal pools that form
here on top.
But back down below, in the Agate Desert landform, a different
sort of barrier holds water at the surface.
"If you look down the road cut here, you can actually
see a pretty-much continuous line of this durapan. It's just
like a solid layer that the pond water can't soak down through,
so it sits here on the surface like on a table top."
Darren Borgais works for the Nature Conservancy, which owns
this property. He says the layer of cement-like hardpan underlies
all 32 square miles of Agate Desert. Which explains why vernal
pools are, or at least were, a defining feature of this whole
"This is all part of the Agate Desert landform."
The terrain is bumpy; it's classified as mounded prairie.
And its poor drainage discourages many kinds of agriculture.
"Vernal pools are very interesting systems. They're probably
the most pristine ecosystem that we have left in the Western
states, especially below 4-5,000 feet."
Like many other natural environments, the Agate Desert has
been altered by weeds and other non-native species. But biologist
Brent Helm says that within the vernal pools, the unusual
life cycle has prevented many outsiders from taking hold.
"It's a very harsh system for species to colonize, so
we don't have a lot of exotics that are getting into them."
Introduced plant species thrive on the mounds all around.
But the pools themselves contain mostly native plants and
animals, well-adapted and living together as they have for
thousands of years.
"We are looking at communities of organisms and ecosystems
that are fairly unique."
Michael says the pond environments provide great learning
opportunities for his students. Though he admits that getting
them interested in wildlife this small can be a challenge.
"People look at them and they're not beautiful, they're
not striking, from a distance -- until you really get in and
start looking at them closely."
So back in his classroom, he's mounted a video camera to
a microscope. He says once the class sees the tiny creatures
on the big screen, the students are hooked.
"These are ostrocods; some people call them seed shrimp.
They're a little crustacean." "These are copepods;
this is another branch of the crustacea."
"Those clusters on the back are egg sacs, so those are
the females. You notice that they're bright red. They actually
incorporate pigments from some of the algae that they eat."
"One of the things that's neat about these vernal pools,
they're too short-lived for most predators, particularly fish,
to live there. And so you develop these particularly interesting
invertebrate assemblages that anywhere else, where there were
fish or other vertebrate predators, you wouldn't see them."
"These are flatworms, tubolarians. They're real common
in the ponds, too." "Oh, look at that, daphnia.
Actually these guys are all gals. They're all females. When
they reproduce, they reproduce entirely through parthenogenesis,
meaning they don't need to have sexual reproduction. They're
He has saved the star of the show for last.
"This is the sexy vernal pool invertebrate, a fairy shrimp,
order anostrica." "And you can tell the male because
he's got these really large modified second antennae, that
he uses for clasping the female and also for battling with
other males for access to females."
This is a federally listed threatened species, identified
here in Oregon only a couple of days earlier. And it may push
the subject of vernal pools into the public spotlight. "There's
the female. Isn't she pretty?"
The fairy shrimp is already well-known, and controversial,
in California's Central Valley where Brent lives. "Because
it is a listed species, it has all the protections afforded
to it. So you need to have a take permit to kill this or to
fill a vernal pool in."
Some landowners and developers there have even sued to get
the shrimp delisted, claiming it is more plentiful than once
believed. Its discovery here in Oregon will fuel that debate.
But unless its threatened status is reversed, the shrimp will
surely change the way the Agate Desert lands are managed.
"A lot of the land around here would probably have to
be surveyed for the fairy shrimp if there's going to be any
sort of development in the region." "Check this
guy out. This is a dytiscid beetle larvae. They're the top
predators in most of these systems. Fairy shrimp and other
invertebrates probably fall prey to these predators quite
For Michael, the real issue is not whether individual vernal
pool species are endangered. He says the entire ecosystems
they live in are important and at risk. "You don't have
to be a biologist to appreciate the diversity of life you
find in those pools. And how interesting it is that those
organisms can live and have evolved under those conditions."
And, of course, small animals are only half the story out
here. "This one is a member of the renunculacae, called
As you might expect of a botanist, Frank Lang studies the
plants. "Here's another interesting vernal pool plant,
this is coyote thistle, and it's in the same family as carrots."
It's now late April and the pools are starting to recede.
The crustaceans have perhaps met their fate in the jaws of
dytiscid beetles, but not before laying their eggs in the
sediments to hatch out next year.
This is the part of the pool's cycle where the flowers take
center stage. "One of the first ones that you see is
this popcorn flower." "This is pillwort. They reproduce
by means of spores instead of seeds."
These pools are true micro-habitats, home to a much different
set of plants than the higher ground only a couple feet away.
"This plant is very common. And what we'll do is walk
over here to a vernal pool that has lomatium cookii in it.
This is very rare. This is it; this is it for the world."
And this is a kind of meadowfoam, similar to that grown
in the Willamette Valley for its high quality oil.
"These plants, the only place you find them are associated
with these vernal pools. This particular subspecies, just
right here on the Agate Desert."
It, too, could have some agricultural value. Because unlike
the Willamette Valley type, which needs bees for pollination,
this vernal pool type is self-pollinating. But Frank says
that, like the other plants here, this one's real value lies
beyond any commercial potential it may have. "You know,
it's the product of millions of years of evolution. It occupies
a niche in the ecosystem. It's interesting, you know; that's
a reason to keep it." "It's pretty hard to make
an argument that those organisms will ever be the cure of
cancer or any of those kinds of things, but I think they are
unique. And they are part of the evolutionary and ecological
legacy of this area." "You know, it's an ideal industrial
site, but in terms of biological and ecological values, it's
irreplaceable. Once it's asphalted, that's the end of it.
And there's not much of this habitat left."