Microscopic Critters of Guam
by Brenna Lorenz
This page is devoted to the
freshwater microfauna of Guam. We have the BEST microorganisms! If you
live on Guam and you have access to a microscope, get to know these micro-critters
yourself! All drawings on this page are by Brenna Lorenz unless otherwise
indicated, and are pictures of the living organisms as they appear under
I have already mentioned the
Madog River that flows through Umatac, beneath the fancy Spanish-style
bridge that Ricky Bordallo built when he was governor of Guam. Click
here to view another photograph of the beautiful Madog
River.In addition to the big animals that live there, the carabao
and the friendly pig, the toads and their offspring (all of whom you can
read about on Critters of
Guam), the gray fish, the white eels, and the shrimp, the lush waters
of the Madog River are home to a glorious array of microscopic organisms.
Paka, the Madog River has been very much rearranged. It used to be
possible to follow it up one branch or another all the way up into the
mountains. But debris washed down from the highlands has produced an impenetrable
tangle of mud, dead vegetation, and unfriendly new live vegetation that
has plenty of thorns and aggressive seeds, and that tends not to grow vertically.
The river seeps through all of this in a diffuse oozing of water until
it reasserts itself as a normal stream in its main channel.
I collected some of the water
from the stagnant parts, along with some algae and some mud from the bottom.
Although I tried to avoid collecting tadpoles, I ended up with three. They
were too numerous to avoid, and when I tried to skim them out of the jar,
they burrowed into the stuff at the bottom. It was too bad. They were dead
by the next morning. The next time I collected some water there, however,
the tadpoles fared better. Some of them are still alive.
I brought the water to Animal
Diversity lab, where the students were starting the semester with a look
I have often said that the
best pond water I have ever seen is the stuff from the duck pond behind
Mercyhurst College in Erie, Pennsylvania. That is indeed excellent pond
water. But Madog River water is just as good, maybe even better!
Here are some of our Guam freshwater microorganisms:
Click here to view the
drawings of Sarcodines
not shown in the article.
In Madog River, we find Sarcodines, those animalcules that move by means
of pseudopods. At first, all we could see were the little ones with the
burst of rays sticking out, the Heliozoa. These are incredibly gorgeous
creatures. One Heliozoan looks like a grainy green disc surrounded by colorless,
clear cytoplasm, from which the axopodia (rays) emerge. I think that
one is Acanthocystis. Another one, small with a colorless, bubbly-looking
interior, is Actinophrys. A larger, more irregular, colorless, bubbly-looking
one is possibly Actinosphaerium. Recently we have been finding the stalked
heliozoan-like sarcodine, Clathrulina, whose cytoplasm is encased in a
lattice composed of silica.
Later, the culture exploded
with two kinds of shelled amoebae, one of which is plain old Arcella, probably
Arcella hemisphaerica, the round brown one that looks a little like a donut
because of the light area in the middle. But Madog's Arcella is more active
than usual, and it is actually possible to see its skinny little pseudopods.
The other shelled amoeba is much more ornate. It is a light golden brown
color, with a crenulated and faceted shell. Under high power, the shell
has a lacy, pitted appearance. This one is perhaps Arcella gibbosa. This
amoeba, too, is gracious enough to provide the viewer with a view of its
pseudopods, and if you can manage to trap one on its back, you can look
inside its shell and see its protoplasm moving around in there. Most recently,
we have found one (only one) enormous Arcellid (Arcella dentata) with a
magnificent array of seventeen curved spines decorating the perimeter of
As the culture ages, we start
to see more of Difflugia, a kind of sarcodine that lives in a grainy-looking,
sac-shaped test from which its narrow pseudopods emerge. Another amoeba,
possibly related, is an enormous, robust creature with a dirty, shaggy-looking
spherical test. This amoeba has thick, pale green pseudopodia.
Most recently, we have seen
the emergence of a beautiful shelled sarcodine called Euglypha. The shell
is glass clear and covered with glassy shingles. From this vase-shaped
test emerge five long, elegantly-curved spikes. The Euglyphae here on Guam
have longer spikes than the typical Euglypha.
Finally, there are a number
of small, plain naked amoebae, almost certainly Tubulines. One looks like
good old Amoeba proteus, only smaller. This one is your standard amoeba
that sends out lots of stubby, fast-moving pseudopods and is constantly
changing shape and direction of movement. Perhaps it is Metachaos. Another
is a fixed shape and has a definite front and back end. It moves by bulging
slightly at the front end and flowing into the bulge. This one is possibly
Saccamoeba. Most recently, we found a large, long-limbed amoeba that might
actually be the famous Amoeba proteus. Then
we got swarms of spiky-looking naked amoeba.
Click here to view the Sarcodine
These are particularly abundant
in the water of Madog River. Click here to view Ciliates
not shown on this page.
We find Paramecium, the standard
text-book protozoan, a flexible, lively, light brown slipper-shaped ciliate
that rushes around through the water droplet unless it has stopped to graze
on the debris. Madog River water passes through a ciliate explosion phase
about two to four weeks after it is collected. During ciliate max-out,
the water droplet on the slide will be dense with paramecia and other ciliates.
After being on the slide for awhile, the paramecia form a line around the
edge of the cover glass, all lined up perpendicular to the edge, as if
peering out past the edge of their universe.
We find Vorticella, of course.
These are the hyperactive little bell-shaped ciliates that have a long
stalk connecting them to some substrate. They coil up their stalk and pucker
up whenever they are startled, which happens a lot. If one breaks free
of its substrate, it swims in frantic circles, trailing its stalk. Lately
we have seen a lot of Vorticella dividing. In the books, they always show
a little bud growing off the side of a big Vorticella, but I never see
that. They start out looking like they have been stretched out sideways,
and then they split into two equal-sized bells connected at the base to
We also find the colonial Vorticella
equivalent, Zoothamnium, in which the individuals are arranged like a branching
tree, and the whole colony contracts at once.
We find Urocentrum turbo. This
is a ciliate protozoan that looks like an acorn with a spike coming off-center
out of a dimple at the bottom. The protozoan constantly spins around like
a top, which I guess is why they call it "turbo." They seem to have
no preference for either clockwise or counterclockwise spin direction.
This is a fun organism to see, and to make it even better, these guys were
dividing like crazy when we first spied on them through our microscopes.
When a Urocentrum turbo first starts to divide, it looks like it has a
roll of fat around the middle. You notice that it has three lumps instead
of two. When it's just about finished, the two new Urocentrum turbos are
hooked together side-by-side, connected by a curved bridge of protoplasm
connecting their caps. The whole thing is horseshoe shaped and very confused,
unable to spin and not having much luck traveling, either. Megaera and
Malachi and I think that a giant-sized Urocentrum turbo would make a great
monster for the Godzilla series. Are you listening, Toho?
We find Frontonia. These are big
(huge!), brown, elliptical, plush-looking ciliates that resemble Paramecium
somewhat, but are bigger and not slipper-shaped. When we first looked at
the Madog water in Animal Diversity lab, the Frontonia were all full of
stuff that looked like straw. Since then, they have digested whatever that
was and have been eating stuff that is less distinctive. The second week,
I found two Frontonia conjugating. In all my years of looking at pond water,
I had never seen protozoans actually in the act of conjugating. I had read
about it, of course, and seen diagrams, drawings and photographs, but seeing
it with my own eyes was very exciting. So I said to all the students, "Hey,
everyone, come look at these Frontonia! They're conjugating!" Not a single
student got up to look. Their professor had told me that she had lectured
on conjugation that morning, but apparently the implications hadn't sunk
in yet. So I said, "Come on, you guys! These Frontonia are having sex!"
Instantly, I had a long line of students waiting to peek through my microscope.
One student stared for a long time. Then she said, "I can't see anything."
I looked to make sure that the mating couple was still in the field; they
were. "They're still there," I told her. (Considering how big they are,
they're hard to miss!) "But they're not doing anything," she said. "They're
just swimming around stuck together." Lately some of our Frontonia have
been going around sporting an enormous vacuole in their middles, easily
a third of their total size. And the other day I got to see a Frontonia
engulf an algal strand, sucking it in like a person eating spaghetti. The
algal strand was slightly longer than the Frontonia, but that didn't seem
to cause any problems.
We find lots of Euplotes. These are stiff, spiky ciliates that look oval-shaped
from the top, but are convex when viewed from the side. Their cilia are
fused into cirri that serve it as legs. When they crawl around on the debris,
they look distinctly insectlike. In the same drop of water that had the
conjugating Frontonia, we found some conjugating Euplotes. That's an interesting
sight, considering how spiky they are!
We find Spirostomum. These are
big, long, dark brown, cigar-shaped ciliates that scoot around very fast.
Their cilia are arranged in an attractive, longitudinal spiral pattern.
This pattern and the lack of eyespots help to distinguish them from worms.
Of all the organisms in the river water, these are the most stable and
persistent. They are there from the first day to the last. Most of our
Spirostoma are small (relatively speaking), about two Paramecia in length,
but the other day a light brown monster Spirostomum showed up, only one
of them, and it was three times the length and width of the other Spirostoma
in the slide. The monster had a long spiraled, beaded macronucleus going
down the length of it, and lots of visible internal structure.
We have seen rather strange
things among the Spirostoma. For example, they develop a swelling, usually
at the end, that makes them look like swimming microphones. Sometimes the
swelling is about 1/3 down the length of the cell. They also look
sometimes as if something had bitten a funny, squared off chunk out of
them about 1/3 down their length, and sometimes one looks like a big one
with a little one hanging off it about 1/3 down its length; the big one
has a funny, squared-off end with its cilia sticking out. We have also
seen some little ones conjugating. Sometimes they appear to be crumpled
up, or tied in knots, or chewed up. Possibly they are big enough
to survive attacks by the Madog River predators such as Lacrymaria olor,
Coleps, and the nematodes, and we are seeing wounded ones.
Our first sample of Madog River
water never yielded any Stentors, to our dismay. But the second sample
has given us three kinds, a colorless, glass-clear Stentor, a pale brown
Stentor, and a breathtakingly beautiful aqua-colored Stentor. As I looked
at the long, skinny aqua Stentor attached to a matrix, I accidentally jarred
the microscope a few times, frightening the poor, nervous creature. At
last it scrunched itself into a small turnip or garlic-shaped lump and
We find lots of Halteria. These
are somewhat smaller ciliates than the others, rounded but oblate, with
a couple of fringes of cilia running around their lines of latitude. They
hop about frantically, and are hard to see without Proto-Slo.
These funny-looking ciliates
resemble Frontonia or Paramecium except that they have a hook at their
front end. They are flat and flexible. They seem to arrive a bit late in
the ciliate max-out phase of the culture, after the Frontonia, Paramecia
and Urocentrum turbo have peaked and are in decline. During their latest
appearance, they were conjugating.
These long, skinny guys look like
Spirostomum except that they have a long, flexible nose that they follow
around. The "nose" is quite a lively probe.
These incredibly malevolent
looking little ciliates resemble Litonotes slightly in that they also have
a long nose. However, the resemblance ends there.
The first time I found Lacrymaria
olor, the beast was hiding in a clump of debris, and all I could see of
it was its questing nose or neck. At the end of this neck was a bulb or
swelling. It whipped this tentacle around rapidly in all directions, elongating
it and retracting it. At one point, it touched a Frontonia, and apparently
grabbed it for a second. The Frontonia pulled away and dashed off. I have
since learned that Lacrymaria tears chunks off other protozoans for its
nourishment. That day, although I watched this organism for a long time,
I never got a glimpse of its body, because it never came out of its hiding
place. I had no idea that it was a protozoan. It just didn't move like
But the next day, I found
one out in the open. That tentacle or neck is unmistakable. This time,
I got a good look at it and could tell it was a ciliate. After that, it
was easy to track down its identity. Check out this website for a good
article about Lacrymaria
Prorodon is a round, simple-looking
ciliated ellipsoid, slightly pointed at one end. Ours are fairly dusky
in color, a sooty gray. They tend to show up fairly late in the ciliate
This funny-looking ciliate bloomed
recently in our Madog River sample. These guys are barrel-shaped with a
circle of cilia around their base and a spiraled ring of cilia around their
oral end. When startled, they contract like a stentor or vorticella.
Click here to view Ciliates
not shown on this page.
We find Bacillaria. This
amazing colonial diatom moves by stacking or folding itself up, and
then straightening out to push itself along. Bacillaria is very active.
It is so funny looking that people laugh out loud when they see it.
If you are interested in ordering
a book to help you identify Protozoa, check out How
to Know the Protozoa at amazon.com.
If you are interested in seeing
lots of very helpful pictures of Protozoa on the Internet, check out Protist
In addition to all of these protozoans,
we found several multi-cellular animals inhabiting the water of Madog River:
We found Dero. This is an oligochaete
annelid worm with ciliated anal gills that look like a hand. The Dero was
large enough not to be terribly happy confined between slide and the cover
slip, so it didn't move around very much. We could see its little eyespots,
and its pulsating insides. The second time I found Dero, the students were
studying annelids, so I called them over to have a look. When I told them
I had found Dero, a worm with a funny-looking butt, a student said, "A
worm named Daryl?" The first student in line looked at Dero and said, "I
don't see a hand. All I can see is eyes." "You've got the wrong end of
Dero," I said. "Look at its rear end." She moved the slide, and exclaimed.
"Oh, my God, it's excreting! It does look like a hand!" Then she burst
out laughing. The students all admired Dero's physique.
Then we found another beautiful
annelid called Aeolosoma. This one is smaller than Dero, and is profusely
decorated with brilliant red spots that look like tiny rubies. Aeolosoma
has no obvious eyes, and has a funny, distinctive spoon-shaped head. Originally
classified as an Oligochaete, it is now put in a class of its own. Later,
we found a larger, less flashy Aeolosoma with brown spots, and an even
larger one with pale green spots.
We found several kinds of Turbellaria,
but only one Dugesia (planarian). Most of our Madog River turbellarians
don't have the cute crossed eyes or the big cheeks, but they are still
lively and appealing flatworms. One kind had divided, and the two new worms
were still hooked together. In fact, these double worms are moderately
common. In addition to the double worm, which has little transparent
sensory pits that resemble eyes, we found a flatworm with larger, bean-shaped
eyespots with scowl lines above them, and knobbly skin on its body, and
another one, similar in shape and knobs, but larger with no scowl, and
orange in color. A fourth kind we have named Plain Old Worm (POW), because
it has no eyespots, no knobs, no color, no anything. Its head and its rear
look the same and it seems to be equally content to travel forward or backward.
One can see its gut through its transparent gray skin, and that's about
We had despaired of finding
a good old planarian and had just about given up on them, when one showed
up in a wet mount on lab exam day. This huge, coal-black planarian streaked
across the slide and disappeared under some debris. When we found it again
later, it was obviously unhappy. It had scrunched itself up into a black
rectangle with eyes, and we hope it lived out its natural lifespan when
we put it back in the culture bowl.
In a later glimpse of the
water, there were two handsome, tan flatworms cruising around together.
I say "together" because they never moved far away from each other in the
slide. I would have expected the two to be cruising randomly relative to
each other, but they definitely stayed close like a couple of pals.
Most of these worms can and
do cruise around pretty fast, but one type, which I think is a rhabdocoel,
was a slow-moving flatworm; it hardly moved it all. I saw only two of them
altogether. You can see a picture of one on the flatworm page.
Click here to see more pictures of our beautiful
We found rotifers, of course,
many different kinds. Rotifers are small, protozoan-sized, multicellular
animals possessing a crown of cilia, called a corona, and a set of jaws
called a mastax. These are the two most distinguishing characteristics
of rotifers. The beating cilia of the corona make the corona look like
a wheel, which is where rotifers get their name, "wheel-bearer." In old
fashioned books, you may see rotifers refered to as "wheel animalcules."
The mastax is always churning and moving as the rotifer chews on stuff.
Several of our rotifers belong
to a group called the Lecanes. These have a rigid shell. Pictured is a
Lecane with a keel on its back.
Philodina is a common freshwater
rotifer, and I have read that it is the most common animal on Earth. It
is a soft-bodied, fairly large rotifer with an attractive double corona.
It likes to attach itself to algal strands, and then stretch out to feed.
It can crawl along the algal strand like an inchworm or a leech, and in
fact it belongs to a group of rotifers called the Bdellids, which means
"leechlike. " One intriguing fact about the Bdellids is that they are all
Philodina is also capable
of launching itself free of its substrate and swimming quite rapidly through
The last time we looked at
our Madog River water, at a sample collected during the month of November,
we saw large numbers of Philodina hatching from eggs. The eggs are large,
and the animal emerges looking like a full-sized adult. The shell splits
open and the rotifer wiggles out with great difficulty. She has a hard
time getting the shell off her back, and she wriggles, bucks, and rubs
herself against things trying to get free!
You just wouldn't believe that
this creature is a rotifer! The cilia of its corona are elongated and motionless,
and it uses them to filter small prey out of the water.
Collotheca's tentacles are
barely visible under the microscope, they are so slender and fine. The
tentacles look a great deal like a heliozoan's axopodia. The Collotheca
holds its tentacles rigid and still, and as long as the creature is standing
at attention, the only movement one can see is of its mastax. But Collotheca
is contractile. If you startle it by bumping the microscope, it retracts
like a Vorticella, pulling its tentacles inside. The tentacles re-emerge
soft and limp until the creature is outstretched again. The one depicted
here appeared to have four clumps of tentacles, but one that we saw the
next day had five.
Click here to see more pictures
and descriptions of rotifers.
We found Ostrocods. These are
crustaceans wearing a dark gray bean-shaped shell. The shell opens like
a clam shell, and the ostrocod's little legs stick out. The ostrocod has
a single glowing red eye.
One of the most exciting animals
we found are the Gastrotrichs. The merry gastrotrich is a friendly-looking
little transparent creature smaller than a Paramecium, with a big round
head, and a short little bristly body with two tails. It waggles its head
back and forth as it swims, and occasionally turns a somersault to change
direction. Viewed from the top, it looks like it should be round like an
old-fashioned clothes pin, but when it somersaults, you can see that it's
actually flat. Some of our gastrotrichs were pregnant, giving them a hunchback
appearance. The students declared that the gastrotrich looks like a cross
between a turtle and a snail.
We were a good month into our second batch of Madog River water when we
were shocked, amazed and tremendously delighted to find Hydra viridissima,
the greenest of hydra! Our hydra was a male (for the moment), with breast-shaped
spermaries and a large bud. (Hydra are serial hermophrodytes, which means
they can change from one sex to another.) His long, skinny, nematocyst-studded
tentacles writhed constantly, and he (and his bud) would contract and elongate
again as they responded to activities of other critters. At one point,
a large flatworm practically swam into his mouth. The hydra grabbed at
the platyhelminth, but the nematocysts had no noticeable effect. For all
the activity, we never saw the hydra actually eat anything. The green
hydra is an awesome and beautiful creature!
Since spotting our first hydra,
we have seen several more. One was asexual, but most of the rest were males.
We have not yet found any females.
I must confess, I don't care for
nematodes. They have a malevolent look, and in fact a great many of them
are parasites. Another prejudice I have is that they all look alike: long,
skinny, hairless, unsegmented and frantic. Nematodes have a distinctive
way of writhing, looking like they are trying desperately to get away,
but are trapped and unable to get anywhere. And that is why the nematode
pictured here first caught my attention. It was hardly moving. And staying
still is something nematodes just don't do!
This was also a particularly
large nematode. I gave it a second look and found that its head was attached
to a slightly wrinkled
round thing. It looked like it was feeding on the round thing. Then the
nematode pulled loose for a second, and I saw an evil-looking proboscis,
or stylet, or hypodermus, withdraw into its mouth and then reemerge.
It pierced its victim with the stylet again, and as I watched, the prey
slowly shriveled into a raisin. The victim might have been a Philodina
or a Frontonia; by the time I saw it, it was too far gone to tell.
Later I saw the nematode probing
around among the algae with its ferocious-looking snout, looking for another
victim. A few days later I watched while another nematode of this kind
searched for prey. The nematode sniffed a big flatworm and rejected that.
Then it ignored a giant Frontonia. From the way it nuzzled along the algal
strands, I suspected that it was searching for rotifers. And sure enough,
when it encountered an unfortunate Philodina, it struck. One blow, and
the Philodina pulled in her corona and never moved again. The big nematode
sucked her dry.
Since then, I have seen these
big nematodes bypass stentors, vorticella and other ciliates, but attack
both Lecanes and Philodina. They are rotiferivores.
Naval Magazine Puddle Water
Dr. Lynn Raulerson gave me a ziplock
bag full of brown water. She said, "Someone brought this to me last week
with a plant in it. It comes from Naval Magazine. You might want to look
at that and see if there's anything in it." I held it up to the light and
saw some large worms about an inch long gliding through the murk. "We won't
even need to use microscopes to see these guys!" I exclaimed. I showed
Lynn the critters, and she said, "Oh, wonderful! Those are leeches! That's
what the students are studying right now!" She went on to say that these
leeches are fish leaches or bird leeches, but they never bother people.
I poured the Naval Magazine
water into a glass bowl, but the leeches stuck to the bag and wouldn't
come out. I finally had to turn the bag inside out and pull the leeches
off with forceps. The leeches stretched until I was afraid that they would
break, but then they would let go of the bag with an audible pop. Then
they adhered to the forceps. I finally got one into a little staining dish
with some water and handed it to a student. The student carried off the
But a few minutes later I heard
a great deal of squealing and shrieking. "Oh, my God! It's crawling out!"
The leech was returned to me in a hurry!
Perhaps the finest animal we
found in this water was the rotifer, Floscularia. This rotifer lives in
a home of its own construction. It looks like a waffle cone composed of
small, golden-brown hexagons. The waffle cone is a little less appetizing
when one realizes that it is composed of the rotifer's own feces and mucus
rolled into balls and pressed into place in the structure. The rotifer
can pull down inside and hide, or it can stick out its four-lobed corona
for food-gathering purposes. One student described the corona of Floscularia
as looking like a buzz-saw.
If you are interested in ordering
a book that is a guide to identifying microscopic organisms, check out
Guide to Microlife at amazon.com. This book is a good introduction
to freshwater microorganisms, with beautiful photographs, but its coverage
is somewhat limited. However, there's not much out there to compete with
A great website with lots of
articles about microscopy, including information about microscopes and
what can be done with them, as well as what can be seen with them,
is Micscape Magazine.
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