PREFACE: Late in our pre-teen years--1958, to be exact--Paramount Pictures released to movie houses a double-feature (remember them?) that scared us enough we stopped going out after dark for a few weeks. One of the films was I Married A Monster From Outer Space (movie poster below), in which human males are kidnapped by aliens who resemble them completely and desperately want to breed with human females because all their alien mates have gone extinct. These extraterrestrial imposters are impervious to everything except German Shepherds that rout the invaders and cause them to depart Earth ever-so-quickly in their silvery space ships. This was pretty straightforward science fiction that had no lasting impact on our psyche.

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Movie poster above courtesy Paramount Pictures

The other flick--The Blob (movie poster below)--was far scarier and starred an amoeboid alien that hitchhikes inside a meteorite and lands in Phoenixville PA (apparently not far from our hometown of Pittsburgh). After emerging from the hot rock, The Blob consumes one human after another, increasing in size with each ingestion. This invertebrate creature flows hither and yon around Phoenixville until the penultimate scene in which it engulfs an entire diner with people inside. When fire erupts the diner owner grabs a fire extinguisher and discovers carbon dioxide foam causes The Blob to pull back its pseudopods. Employing true deductive reasoning, the hero--Steven (later "Steve") McQueen in his first "big" role--concludes the shapeless alien can't tolerate cold CO2 and gathers enough fire extinguishers to douse The Blob into half-frozen submission. An air force jet flies the now-inanimate Blob to the North Pole for safe keeping as the movie concludes with the words "The End" changing into a big question mark. That interrogative punctuation (?) was what scared us most and we spent several sleepless childhood nights worrying the big amoeba might somehow rejuvenate and return to consume us all.

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Movie poster above courtesy Paramount Pictures

In one of life's little ironies, a few weeks ago we happened to be listening to an oldies radio station while driving back from West Virginia. We were surprised (and a little bit chilled) to hear half-century-old strains of "Beware Of The Blob"--the sci-fi movie's ominous theme song penned by then-unknown Burt Bacharach and Mack David (brother of Hal). Now that polar ice caps are melting at an unprecedented rate we even began to wonder if the formerly frozen Blob might thaw out and show up somewhere near--perhaps back home at Hilton Pond Center. With that frightening thought resurrected, you can guess what happened next . . . .

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This week we walked out on a pier on Hilton Pond and there . . . attached just below water level to a floating dock . . . waiting for us to come near was . . . YIKES! . . . THE BLOB! Well, it might not have been THE Blob--portrayed in that fifties-era cult film as a blood-thirsty blood-red amoeboid (movie out take, below right)--but it was A blob nonetheless, an irregularly shaped, nearly colorless creature growing on the submerged end of one of four white plastic barrels that keep the dock afloat (photo above). We couldn't remember having seen or heard any meteorites striking our pond in recent weeks, so--keeping as calm and objective as possible and trying not to worry about any alien danger resurrected by global warming--we concluded the amorphous mass on the dock probably wasn't a human-hungry outer space Blob after all. In fact, we even recognized what the thing in the pond actually was: A Bryozoan whose ancestors arose during the Upper Cambrian Period about 490 million years ago--long before the infamous movie star Blob ever came to terrorize Earth.

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Haeckel's bryozoan print courtesy Panteek

Bryozoans are indeed quite ancient creatures that originally inhabited primeval oceans along with trilobites and primitive chordates. Marine plants were plentiful at that time, but the only land "flora," if any, were algae and fungi and commensal lichens. Bryozoans continued to evolve and disseminate, and when freshwater pools became available a relative few became adapted to this new habitat. These days there are still plenty of bryozoans around--as many as 4,000 species worldwide and 500 marine varieties just in Australia's Great Barrier Reef. (German zoologist Ernst Haeckel's classic rendering above from the late 19th century illustrates several modern saltwater species and their attributes.) Despite their abundance in marine habitats, however, only about 20 or so freshwater bryozoan species can be found across North America.

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So exactly what were these blobby creatures (above) we found lurking in Hilton Pond? First of all, bryozoans are invertebrate multicelled aquatic animals in their own phylum, the Bryozoa, which means "moss animals"--so-called because some crust-like species resemble delicate little moss plants. Most bryozoans form sessile (immobile) colonies consisting of many individual "zooids" that are more or less interdependent. Within a colony, some zooids are responsible for feeding and excretion, some play defensive or cleaning roles, while still others may serve as hatcheries for new zooids. Each individual feeding zooid has a "crown" of ciliated tentacles that filter water for food particles. (See photo above left of two zooids of a European freshwater bryozoan, Lophopus crystallinus.) While feeding, a zooid protrudes from the colony surface and waves its tentacles in the water, pulling detritus and other nutritious particles into its stomach. At rest or when disturbed the zooid withdraws to its own private chamber (zooecium), which is why you're not likely to see the barely macroscopic zooid or its tentacles in action out in a pond. The whole bryozoan colony includes lots of zooids--thousands, or even millions in a big specimen--each only about 1/32nd of an inch across.

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Bryozoan fossil photo courtesy Mark A. Wilson, College of Wooster

Colonial zooids typically are bound together in a case made of chitin or calcium carbonate (usually configured in the shape of a crust, fan, or antler), or of a more-or-less slimy gelatinous substance that forms a "blob." In the aggregate, calcareous bryozoans (those that form calcium cases) can leave large fossil deposits (above) that resemble those from corals or sponges; gelatinous colonies are less likely to fossilize and leave almost no mass when they do. Healthy bryozoan colonies enlarge by "budding," a process through which individual zooids make multiple clones of themselves; new colonies arise either from fragmentation (in which part of a colony breaks off and floats to new substrate) or sexual reproduction (with eggs from one colony being fertilized by sperm from another). Needless to say, bryozoans can be quite prolific.

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We're not expert on bryozoan taxonomy and lifestyles, but we're pretty confident the blobs colonizing our Hilton Pond pier are the Magnificent Bryozoan, Pectinatella magnifica, characterized by an irregular, translucent, gelatinous mass (99% water) and an outer surface marked underwater by whitish star-shaped rosettes (above) that under a hand lens are shown to be comprised of a dozen or so zooids. Such blobs are sometimes mistaken for egg masses of frogs or aquatic insects. Colonies of this freshwater "moss animal" can reach diameters of six feet or more and sometimes take on a purple hue.

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As we looked around the dock area we discovered several more colonies both on the float and on the underwater posts that held up the pier. (We suspect lots of other bryozoan colonies were attached to submerged sticks and logs elsewhere in the pond.) Since the species appears to be thriving locally, we used a sharp knife to cut away a small portion of one colony for closer examination and placed it in a white bucket filled with pond water. Out of the sunlight and against a lighter background the blob looked very different; the white rosettes now appeared dark and almost fractal-like (above).

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Even more interesting, when we placed the colony fragment into our bucket, it seemed smooth. After leaving the bucket undisturbed for several minutes the colony then changed its appearance and became fuzzy-looking (above)--the result of thousands of zooids coming out of individual chambers and starting to wave their tentacles.

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Out of water the clear jelly that makes up most of a colony's mass was easily seen (above left). However, if we re-submerged the blob the rosette-covered surface remained visible while the jelly disappeared completely--meaning pond water and bryozoan jelly must have the same refractive index. (We thought this was pretty cool; it would make a nice biology-related demonstration for up-and-coming physics students studying light and matter.) Incidentally, the reddish-brown worm-like creature (above right) tunneling within the clear jelly appears to be the larval stage of a chironomid--one of the non-biting midges. Larvae of these mosquito-sized flies are often commensal with freshwater bryophytes; i.e., the two species live together but neither one hurts or particularly benefits the other.

Originally found in the U.S. east of the Mississippi River, the Magnificent Bryozoan now occurs at numerous disjunct locales across North America; dissemination likely accelerated when colonies growing on hulls of private watercraft were hauled from one watershed to the next. This species also disperses via "statoblasts," tiny spore-like resting stages armed with little grappling hooks that cling to feathers or fur of animals that unintentionally transport them--sometimes over long distances. (See freshwater statoblast image above right, courtesy Elsa Fougere & Michelle Golub.) And here's a significant factoid: The Magnificent Bryozoan is intolerant of water temperatures below about 60 degrees F. That means the blob's recent and rapid expansion into previously cooler lakes in the Pacific Northwest is almost certainly further evidence for widespread climate change. How interesting that a freshwater bryozoan might be an indicator species for "global warming."

Although considered invasive outside its historical range that also includes Europe, Japan, and Korea, the Magnificent Bryozoan seems to cause few problems other than clogging drainage pipes in some lakes and along rivers. (Some locales do report problems with bryozoans at water treatment plants.) The species' natural predators are snails, insect larvae, and fish. We should point out that some ecologists are concerned big populations of filter-feeding P. magnifica can clarify bodies of water so efficiently that more sunlight reaches the lake bottom, allowing accelerated aquatic plant growth that in turn upsets a lake's natural balance.

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One other thing about bryozoans we never would have known had we not put part of a colony in our white bucket: Just a few hours after we collected the sample blob the bottom of the bucket became littered with very, very small brownish specks. These were solid waste pellets produced by zooids and eliminated through their only-slightly-larger anal openings. If mammal droppings are called "scat," if birds excrete "whitewash," and if caterpillars make "frass," we wonder if there's a special name for fecal fragments from a bryozoan. We bet there isn't, so as of right now we're calling it "broop." (Please ignore any other scatological definitions you might find for this word, including one from Brandeis University.)

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In their aquatic habitats bryozoan colonies are active day and night, with individual zooids constantly waving their tentacles to filter food particles from surrounding water. (The ghostly images above and below of Magnificent Bryozoan zooids in action were taken with our Canon 7D and MP-E 65mm macro lens set to 3:1 and 4:1, respectively.) We had seen freshwater bryozoans only once before a few decades ago while swimming at a recreational park on Lake Wylie near Rock Hill SC and hoped someday to find a few in our one-acre impoundment at Hilton Pond Center.

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As filter feeders their presence indicates good quality water rich in nutrients, so we were pleased this spring to finally find bryozoan blobs close to home. Had these interesting organisms emerged from water this week to attack we would have known they were fearful "Sons and Daughters of The Blob," and we would have followed the lead of Steve McQueen--freezing the little monsters with carbon dioxide from whatever fire extinguishers we could find. Fortunately, however, each jelly-like colony was a bunch of harmless water-cleansing bryozoan zooids--NOT offspring of The Blob from outer space that in 1958 struck fear in the hearts of young and old alike. Knowing that, we'll sleep better now.

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