Foam on the Water

Following several days of modest rain there was water once again flowing down the hollows into Bull Creek.  These are ephemeral streams, flowing only after a rain, then holding pockets of water for weeks until they gradually dry out.  Foam appearing in pockets of turbulence always raises the fear of pollution.  So what else could cause foam?

Actually foam like this is a natural phenomenon.  Like the suds in a bath tub, it is caused by a surfactant that lowers the surface tension of water.  Soap is a surfactant made from oil and lye (sodium hydroxide).  This creates a molecule that is water soluble on one end and not on the other,  creating a thin layer of lipids on the surface.  Think of the solution that kids blow bubbles with.

In nature there are natural surfactants called DOC (dissolved organic carbons).  These are formed by the decomposition of algae, aquatic plants, dead leaves and animals that produce oil in the form of simple fats.  As they break down over time they produce fatty acids that are lighter than water and won't mix but lay on top in a thin layer.  In quiet waters this can appear to be a thin layer of oil.  Turbulent water flow mixes air in and viola!...bubbles.

Foam at the falls on Bull Creek

There is frequently a collection of bubbles in an eddy below a little water fall at our swimming hole.  Occasionally this collection will be quite large and can collect little particles on top.   Some biologists use this as a means of looking for exuvia (molted insect skin), aquatic fungi, moss spores, etc.

Of course, foam can also come from pollution so if in doubt, it pays to check.  More details are here.

Good Read:
Insect brains- bigger than you think. 

Heart Without a Head

Fingernail clam adult and offspring - clip from video

Linda Bower* still has her camcorder focused in her neighbor’s farm pond and sent me this story.

This time I was watching fingernail clams (smaller than your little finger’s nail). These bivalve mollusks are in the Sphaeriidae family which includes 12 species in North America. Their more exotic relatives include octopi, cuttlefish and squid. Yes, you read that right. The clams in our ponds are related to some of the most fascinating and intelligent ocean creatures.

According to the Museum of Zoology, University of Michigan, the taxonomy of Sphaeriidae is in a “confused state” even though they are abundant and widespread. It is futile to attempt identifying to a species without a microscope. How did they become widespread without wings? I’m glad you asked. Clam babies can clamp directly onto feathers, mobile aquatic insects, amphibians, or plants that birds inadvertently carry with them. Some species are ingested by ducks, but not digested, and are “released” in a new location.

If you are new to freshwater clams like me, these facts may be of interest:
· Fingernail clams don’t have a head, but they do have a heart.
· They have a muscular appendage called a, “Foot” that is used to move around.
· The mantle (inner lining that sticks out from the shell) can sense touch and light.
· Their two-siphon system allows for feeding and breathing through one siphon, and eliminating  
  out of the other siphon.
· They are filter feeders on very small pieces of organic matter and mini-plankton.
· They are a food source for fish, crayfish, aquatic amphibians, waterfowl and shore birds.
· They are self-fertilizing hermaphrodites.
· The dastardly Zebra Mussels are capable of crowding them out.

Linda's video of an adult and baby fingernail clam gives us a good view of the foot, mantle and siphon. Clams don’t move very quickly, so let’s just say it is relaxing to watch, especially with the music Linda selected.

* Linda Bower is a member of our Springfield Plateau Master Naturalists with a passion for capturing pond wildlife in videos.  More of her video's are at Nature in Motion.

Sweet-toothed Fungus

Ash bolete, with its eccentric stem partially emerging from the ground - Mark Bower

I came across these mushrooms while reading Fascinating Fungi of the Ozarks,*  It looks like a giant clam coming out of the ground but is actually an ash bolete fungus with the catchy name of Boletinellus merulioides. Other sources list it as Gyrodon meluliodes, which I will use, as the abbreviation GM sounds better that the alternative BM.

   Wikimedia

GM only occurs with ash trees but unlike other fungi that are either saprophytic (eating dead wood) or mycorrhizal (sharing nutrition with the plant's roots) this one has a sweet tooth.  It typically has an off-center or even lateral stem.  Rather than invading the ash tree for nutrition, it wraps its mycelium into tiny cups called sclerotia which fungi use to store food reserves.  

  GM sclerotia containing aphids  - Mark Brundrett

PF aphid -  Claude Pilon

In the case of GM, its sclerotia are protecting aphids.  These are not just any aphids but Prociphilus (Meliarhizophagus) fraxinifolii (PF), the "leafcurl ash aphid."  They are specialists that attack only ash trees. 
They feed on the ash trees and and can cause significant damage. They also produce honeydew that is the source of food for the GM.  In trade, the bolete provides the aphids shelter.  

Honeydew is produced by aphids, some scale insects and even the caterpillars of Lycaenidae butterflies.  Some species of ants farm aphids, protecting them from harm in exchange for their honeydew.  An article in Wikipedia explains, "When their (aphids') mouthpart penetrates the phloem, the sugary, high-pressure liquid is forced out of the gut's terminal opening," an icky fact that doesn't seem to bother the fungus.  That gives new meaning to the saying "no guts, no glory."

Exactly how the fungus manages to find the tree and the aphid is unknown but it manages to travel, including to China and Europe, (possibly in an international invasive species exchange program?)  As Mark Brundrett pointed out to me while giving permission to use his photograph above, "I think this fungus may become extinct along with its host tree due to ash borer." On the other hand, it might just possibly survive in its invaded lands.

* Fascinating Fungi of the Ozarks, Mark Bower, 2015.

The Case of the Case-carrying Worm

Dero (Aulophorus) vaga - 1mm - Linda Bower

I was following correspondence from Linda Bower asking Chris Barnhart for identification help after filming an eccentric worm that appeared to be dragging around a decorated case. Chris recognized that the case was partly made of Bryozoan statoblasts (the oval brown objects with a pale perimeter). Chris Barkau, Graduate Research Assistant at Southern Illinois University Carbondale was able to identify it as Tubificida: Naididae: Naidinae: Dero (Aulophorus) vaga.  I asked Linda to describe her find.

Linda:
Case-carrying Worms dwell in ponds with Duckweed, but are often missed by traditional collecting methods. They are tiny – less than 1mm. It was difficult to find recent* detailed information on Dero vaga, also called Aulophorus vaga. We know that it forms protective tubes by means of a viscid secretion from their bodies. You can watch this video of the worm sliding in and out of its case as it searches for food. It is a fascinating dance you won't see elsewhere, and it is free!

Cut and whole Bryozoan colonies - Click to enlarge - MDC

The Case-carrying Worm is interesting enough, but combined with Bryozoan statoblasts? Wow! Bryozoans (aka Moss Animals) are really animals, but given their appearance, that is hard to believe. Bryozoans are a major animal group, having nearly 4,000 known species and only a few dozen of those live in freshwater habitats. They may grow on any submerged object, such as rocks, roots, and branches. They feed on protozoans, bacteria, and organic matter from the water. They are colonial, living in gelatinous blobs.

Most freshwater species produce resistant bodies called statoblasts that form in response to adverse environmental conditions and provide a means of overwintering. As they grow the statoblasts produce bi-valve shells made of chitin, the same stuff that makes the exoskeleton of arthropods (think insects and crayfish). More detailed information on Bryozoans is at this link.

I have filmed several Case-carrying Worms since this first find and here are three additional videos. Do not resist your temptation – follow these links:

• Diversity of cases and size 
• Pooping and meeting another worm - 
• Adding to a case 

Editor's note: You can bail out now or follow along for the details of the complicated life of D. vaga (or if you prefer A. vaga). These tiny (1mm) worms can be found floating within a mass of duckweed or clustered in the algae of the pond bottom, moving up or down based on the availability of food.  Like all other Oligochaeta (worms) D. vaga is a hermaphrodite. It is capable of sexual reproduction or fission. This was described in an 1899 paper, The Natural History and Morphology of Dera vaga.

The period of sexual reproduction occurs during the first two weeks of July, when the body cavity posterior to the clitellum is crowded with eggs.  Asexual reproduction by fission takes place throughout the year, but most rapidly during warm weather, when it may occur as often as three times a week. Three fission zones have been observed in one individual at the same time.

Click to enlarge

As the animal grows in length, the case which it inhabits is extended, and after fission the two daughter worms divide it by placing their heads together at its middle and forcibly breaking it, each worm then swimming away with one-half of the old case. The fission zone is formed near the middle of some segment, usually back of XVII and in front of XXII. The new head and tail are almost completely formed before separation takes place. The number of somites in the new head is constant, being five, while twelve to sixteen segments are visible in the tail before a second fission begins.

Worms divided by cutting regenerate the missing part, though only enough segments are regenerated at the anterior end to complete the cephalized portion, i.e., the first five. Thus if two are removed but two regenerate, while if seven are taken away only five new segments are formed. At least three or four segments in addition to the five in the cephalic region are necessary for the regeneration of the tail. 

*  There are detailed descriptions of this Oligochaete available when searching name variations.  

• The first I could find was On the Anatomy and Histology of Aulophorus vegus was written in 1884.  
• It is named Dero vaga in a 1906 paper in American Naturalist (page 692-3) with the illustration above.
• See also American Naturalist.

Tool Using Wasp

Ammophila procera the Common Thread-waisted Wasp  -  REK

I have been watching Becky Swearingen's video of a Thread-waisted Wasp preparing a home for her offspring.  It appears to be Ammophila procera the Common Thread-waisted Wasp which we discussed in a recent blog.  It had previously brought a paralyzed insect into a hole it had created.  She goes on from there:

"I watched it as it entered the hole, brought out a little bit of dirt, dropped it and then reentered the hole repeating the process. This went on for some time and then the wasp wandered around checking out small bits of rock – tiny pieces of rock until it found the perfect one. She picked it up, went back to its hole and dropped in in the opening, where it was a perfect fit. The wasp then scuffed some dirt over the covered hole and was gone."

A. procera working on its hole for egg deposit - Becky Swearingen.

In Planet of the Bugs, Scott Shaw describes the evolution of wasps' parenting strategies.  In prehistoric times, the earliest versions (Version 1.0) of wasps were gentle creatures, unless you happened to be another insect. Their tail end came equipped with an ovipositor, a tube which would lay an egg on a victim and the larva would emerge and start to feed.  The next versions of wasp (Versions 1.xx) could deposit the egg through the victim's skin.

Sometime in the late Jurassic period, wasp Version 2.0 came out with modifications to the ovipositor, converting it to a stinger, handy for self-defense as well as killing prey for it to feed upon. Some time around then some wasp's venom was modified to simply paralyze the prey, preserving it alive and prolonging the time its larva could devour the insect at leisure from the inside.

With more time, some wasps began picking up the paralyzed insect and hauling it to a protected place, laying an egg on each one before sealing up the entrance.  Mud daubers stuffed their prey in mud tubes while solitary wasps like our thread-waist wasp used holes in the ground or hollow plant stems.  This would frequently include placing a stone in the entrance as Becky describes.  As Shaw* points out, "Wasps were the first stone tool users, tens of millions of years before the first primate or human picked up a rock."

Don't forget to watch Becky's Thread-waisted Wasp video. 

*  Planet of the Bugs, Scott R. Shaw, 2014.  This is my favorite book at present, a breezy look at insect evolution over the last 400 million plus years.  It goes beyond anatomy to describe how behaviors evolved in concert with other plants and animals.