Public Is Invited

Summer 2012 Newsletter

Wednesday, July 11, 7:00 PM – Meet atthe Hermann Fine Arts Center parking

lot, 4th & ButlerHosts: Jim and Gwen Noe

Jim is well-known for raising hundreds ofnative plant species from locally collected

seed. Participants will see hisgrowing-system and the meadow he hascreated near the house. Warning: if you

want to go into the meadow, dressappropriately - Jim reports this is a

banner year for chiggers. Viewing fromthe edge shouldn't be a problem.

Thursday, August 9, 7:00 PM Meet at the Hermann Fine Arts Center

parking lot, 4th & ButlerHosts: Diane and Jim Mitchell

Marietta has miles of riverbanks. Onedoesn't have to go on the river to know thereis a wide variety of management practices. One resident has it figured out and we will

take a look at Diane and Jim Mitchell'sriverbank while they explain how the

natural, stable riverbank was achieved. Protected by native plant species, views of the river can still be enjoyed. How to get all riverbanks so well protected?

Wednesday, September 12, 6:00 PM Meet at Warren's IGA parking lot (upriver side)

to carpool for the 45 minute tripA return visit to see the mysterious swirling flocks of blackbirds

in the annual Bird Event at Luke Chute –a gathering ofblackbirds, grackles, red-winged blackbirds, starlings, cowbirdsand others. Bring lawn chair, water and whatever else you need

to be comfortable for an hour of this Super Show of Birds.

Blackbird Murmuration

Wildflower Nursery?

Marietta Natural History Society

Note that field trips in July andSeptember are NOT on usual

2nd Thursday dates

Page 2 Marietta Natural History Society Summer 2012

Murmurations and SevenBy Steven Spilatro

Understanding the flocking behavior of birds, dramaticallyillustrated in large swirling flocks called murmurations, can provideinsights into other phenomena as well. Similar behaviors are seenin fish schools, mammal herds, some insect swarms, and evenhumans (e.g., clapping in crowds and behaviors of the stockmarket). The rapid, coordinated responses of these groups suggestindividuals reacting as if of a single mind. It has long beenrecognized that for some animals a collective response provides anadaptive advantage in the presence of predators, but how theresponses are biologically choreographed is unclear. “Theremarkable thing about a flock of birds is not merely the globallyordered motion of the group, but the way the flock dodges afalcon’s attack. Collective response is the trademark ofself-organized order as opposed to a centralized one.” Thus therehas been interest in the findings of recent studies of starlingmurmurations. In the The Seventh Starling (http://www.smc.infm.it/attachments/130_significance_lowres.pdf) Andrea Cavagna and Irene Giardinadiscuss the results of the STARFLAG project, which, usingadvanced photographic technology, produced 3D reconstructions ofthe movement of individual birds within flocks of starlings (Sturnusvulgaris). The study has helped to explain not only how the birdsavoid collisions when flying in such tight formation, but also howflock movement is orchestrated. They found, for example, a bird’snearest neighbors in the flock are to its sides, rather than ahead orbehind. This may be because the bird’s eyes are on the sides of itshead, or possibly a “motorway effect” to avoid rear-end collisions,similar to auto traffic patterns. Intriguingly, each bird’s orientation and velocity correlates withthat of its seven closest neighbors; no matter the distance away,each bird seems to be tracking the behavior of its seven closestneighbors. Why seven? Possibly this is the cognitive limit forstarlings, eight being too many to keep track of. But the answermay actually be deeper. The number seven emerges in otherbiological systems, noted by George Miller in 1956(http://psychclassics.yorku.ca/Miller – he also mused over theseven seas, the seven notes of the musical scale, the sevenprimary colors, the seven days of the week, and the seven deadlysins, among others.) See Murmuration, Page 5

A Periodic Cicada Peek? Some people have wondered whether periodiccicadas made a showing in Marietta this Spring.Some specimens brought to the Marietta CollegeDept of Biology have been identified as Magicicadaspecies (which have vivid red eyes). The MagicicadaCentral web site (http://hydrodictyon.eeb.uconn.edu/projects/cicada/magicicada_central/magicicada_central.php ) states that Brood I, endemic to VA and WV,is emerging this year. The areas of Broods V, VIII, Xand XIV (all 17 year cicadas) include OH, but noneare expected to emerge this year – the most recentmajor emergence was Brood V in 1999. GeneKritsky, Professor and Chair, Department of Biology, College of Mount St. Joseph, and Editor of American Entomologist,says what was observed here was a 4 year acceleration of Brood V, similar to a “spurious brood” that was observed in 1995.

Suggestions, Commentsor Contributions for the

MNHS Newsletter?Send them to the Editor:

374-8778 spilatrs@marietta.edu

.

Page 3 Marietta Natural History Society Summer 2012

Recycled Paper 30% Post-Consumer

Butterflies of Summer

According to Common Butterflies and Skippers of Ohio by Dave Parshall and JimDavidson, there are 199 species of these in

Ohio. Their book covers 59 of the mostcommon ones. A nicely formatted and online

version of this book can be accessed athttp://www.flipseekllc.com/wildohio2009butterfly.html

A selection of the species found in Washington County are featured in our calenders, drawing upon information from this book.

Page 4 Marietta Natural History Society Summer 2012

The Blob in the Lakeby Katy LustofinMarietta College

Last summer while out kayaking with some friends atVeto Lake, we encountered an organism like nothing I hadever seen. Initially, I thought I was seeing a partiallysubmerged milk bottle, as it had the same slightly white,opaque color and rough appearance. Closer examinationrevealed a jelly like covering over a firm center, a texturethat reminded me a bit of a jellyfish and a bit of a coral orsponge. Naturally, I brought the sample back to thecollege for identification. My colleagues and I were initiallystymied by this strange organism, which we eventuallyidentified as Pectinatella magnifica, a freshwater bryozoan. Most people are not familiar with byrozoans, alsosometimes called moss animals. Bryozoans are widelydistributed, with colonies found in both fresh water andmarine habitats around the world, including threearctic freshwater species. Each colony is acompound animal, composed of manyindividuals called zooids. Bryozoans, likethe corals they superficially resemble,are sessile organisms that attachthemselves to a substrate and filterfeed. As a phylum,bryozoans havebeen around forabout 500 millionyears, with over 1200 genera described.Currently there are about 4000 extant speciesof bryozoans. The majority of bryozoans are marine, but one class,the Phylactolaemata, is found exclusively in fresh water. Most freshwater bryozoans, like P. magnifica, are not well-known because they are seldom found without carefulsearch. Many of the freshwater bryozoans are small oreven microscopic, and so escape notice. P. magnifica ismore commonly noticed than its freshwater relativesbecause of its magnificent size. Pectinatella magnifica was first described in 1851 fromspecimens collected near Philadelphia. It is sometimesmistaken for a mass of amphibian or fish eggs, having asimilar jelly-like appearance. P. magnifica grows ascolonies that Dr. Timothy Wood of Wright State Universitydescribes as “gelatinous and firm, with a surface that isslimy to the touch.” In the rare occasion that this animalmakes the news, it is typically called simply “the blob,”which is an apt description. The blob, like other bryozoans, is a colony composed ofindividual zooids, which are clones of the founding cell. The surface of the colony is divided into rosettes of 12-18

zooids. The inner mass of the colony is a gelatinous matrixcontaining chitin (the structural protein of insect andcrustacean exoskeletons), calcium, and a protein similar toegg albumin. Approximately 99% of the mass of a colonyis water. Individual zooids are quite small, about 1/64th of an inchin size. The largest colonies are reported to grow about 3feet below the water surface and may exceed two feet indiameter. Most of the colonies I have found locally aresmaller, about 8 inches in diameter, though the one floating

at Veto was slightly over afoot in diameter.

The mouth of each zooidis surrounded by about 50

ciliated tentacles that are used tofilter food from the water. The

mouth region contains a red pigment,while the tentacles appear whitish.

Overall the colony is generallytransparent or opaque with a slight whitishcast. The zooids have a simple nervoussystem but lack sense organs. Eachcolony contains some zooids that are

specialized for reproduction and some thatare specialized for feeding. Bryozoans are

hermaphroditic and reproduce both sexuallyand asexually.

P. magnifica and all other freshwater bryozoans belongto the Phylum Bryozoa, also called Ectoprocta, whichrefers to the position of the anus outside thisring of tentacles. The term bryozoan can beused to refer to both Ectoprocta andEntoprocta, a group of organisms with asimilar appearance but an anus locatedwithinthatring oftentacles. Based uponanatomicalsimilarities, bryozoans havebeen put into agroup together withbrachiopods and phoronids, but molecularevidence suggests this relationship is notactually all that close.

See Blob, page 5

Page 5 Marietta Natural History Society Summer 2012

Blob, cont’ from Page 4 Some websites I found claim that the blob is a relativeof the corals, which is probably based upon the fact thatbryozoans fill a similar ecological role and have a basicbody plan that is superficially similar to corals. Despitethese similarities, they are not closely related to corals. Infact, they are not closely related to any animal with whichmost people are familiar. Although they are not well-known, freshwater bryozoansare widely distributed. Colonies ofP. magnifica can be found in manyfreshwater rivers and lakesthroughout eastern North America. Recently, this species has alsobeen reported in Japan, Korea, andGermany. The blob thrives best ineutrophic and relatively still watersthat are slightly alkaline and are free ofsilt and mud. Colonies can be foundattached to the underside of submergedlogs or twigs, dock pilings, large loose rocks,or floating aquatic vegetation. At North Bend State Park in West Virginia, P.magnifica is frequently found surrounding the treetrunks that were submerged when the North ForkHughes River Lake was formed, which tells me thatat that particular location, there is not much silt inthe water as colonies that experience siltdeposition typically do not survive. Zooids are hermaphroditic, producing both sperm andeggs. Sexual reproduction occurs in the summer andresults in formation of motile larvae. Larvae of P.magnifica are quite small, measuring between 1.5 and 2mm long and 0.27 to 1.25 mm wide. Each larva containstwo zooids and is essentially a miniature colony. The larvaswims for several minutes to 24 hours until it finds anappropriate substrate. Once attached to a substrate, thecolony will began to feed and grow. Because the zooidsare formed asexually, all zooids of a colony are geneticallyidentical to one another, although colonies that areestablished in close proximity may grow into one anotherand function as one colony. P. magnifica, like other bryozoans, also reproducesasexually through budding. The buds are encased inmembrane and jelly to form structures called statoblasts,which are released during September and October. Statoblasts disperse from the parent colony by floating. Inlate autumn, you may find ragged black rafts of statoblastsin the open water or near the shore. These statoblasts,unlike the adult colonies that formed them, can survivefreezing. The statoblasts are dormant throughout thewinter, germinating in early summer when the watertemperature exceeds 64 degrees Fahrenheit. The blob itself does not live through the winter in Ohio,as it survive at water temperatures below 60 F. Thecolonies of P. magnifica die and disintegrate as the watercools to in the fall, leaving the dormant statoblasts to beginnew colonies the following summer. Economically speaking, P. magnifica is not very

important, which may partially explain why it is so littleknown. It has been reported to clog the screens of waterintake systems and grates of hydroelectric plants, but giventhat it prefers shallow and relatively still waters, it is not afrequent problem. This bryozoan does not tolerate manypollutants, and so it can be indicator of good water quality. Because it is a filter feeder, it also contributes to clearing ofthe water in which it is found. After discovering the blob at Veto Lake and North ForkHughes River Lake last summer, I looked for every time Ikayaked, but failed to find any specimens at Dow Lake,Lake Hope, or Wolf Run. Population size boomsunpredictably, so I do not know if I will see it in the same

places this year but I will be keeping myeye out for it as I float –and this year, I will nothave to wonder what the

heck it is.

Murmuration, cont’ from Page 2

In a more recent study (Cavagna, et al.,2010, Proc Natl Acad Sci 107(26):11865-70),

the researchers examined the relationshipsbetween individual and flock behaviors. The authors

found that flock behavior is an unusual example of a“scale-free correlation.” Although a relatively small numberof birds interact directly, the behavior of each bird affectsand is affected by that of all other animals in the flock, nomatter how large. Individual bird’s behaviors affect itsseven neighbors, each of which affects seven moreneighbors, and so on, but without decay through the wholeflock. How this happens remains a mystery but shows thata starling flock behaves as a critical system, like snowcrystals in the moments before an avalanche or aneconomic system before a crash, poised to respond almostinstantaneously to any perturbation. Starling flocks are optimized to thwart predators,whereas midge swarms seem to be related to mating, anda stock market to sustain an economic system. Thestudies of starling murmurations help us understand howcritical systems function, and future studies may provideinsights into other systems. To see a video of starlingmurmuration go tohttp://lightbox.time.com/2011/11/03/murmurations-spectacular-starlings-signal-winter-is-on-its-way/#1.Video From LakeShute taken by Dr.David McShaffrey canbe found athttp://www.youtube.com/watch?v=TfIbLJZrjSQ&feature=plcp

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The MNHS Missioni To foster awareness of and sensitivity to our environment and its biodiversityi To provide a place where people with these interests can gather for information and activityi To create a presence in our community representing these ideas

Marietta Natural History Society P.O. Box 983 Marietta, Ohio 45750 (740) 373-5285