Wednesday, August 31, 2011

Jewelweed's Ballistic Seed Dispersal Mechanism

Who hasn't enjoyed playing with jewelweed's ballistic seed dispersal system?
 Can you resist popping off a few seedpods when encountering a jewelweed patch?
Jewelweed seedpod waiting to pop

I always have to stop and squeeze a few plump seedpods...
  to see the gratifying mini explosion.
Jewelweed's ballistic seed dispersal mechanism in action
 The five outer valves of the seedpod rapidly coil,
 the columella collapses, and the seeds are launched; all in a split second.
Poof!
Here is a link to a paper on the mechanics of jewelweed's explosive seed dispersal.
   The other day when I was trying to freeze (photograph) these explosive seed dispersal events, I noticed a couple of aphids and a tiny green caterpillar on a plump seedpod.  In the photo below, the caterpillar is standing straight as if it is ready for launch, but actually it is trying to hide by pretending to be a stem.  Let's just say this caterpillar doesn't realize what it is sitting on is programmed to explode.
Oh, have you ever seen a caterpillar take a rocket ride?
 Three, two, one, squeeze...
That was kinda' fun!

I was unable to follow the flight trajectory of the caterpillar, but I doubt it was harmed, just suddenly relocated.
Here is a post on violet's seed dispersal by explosion.

Monday, August 29, 2011

Basswood Leafroller Leaf Shelter

There are these neat leaf shelters on Basswood leaves.  These unique leaf shelters are made by the caterpillar of the Basswood Leafroller Moth - Pantographa limata.
Leaf shelter of the Basswood Leafroller - Pantographa limata
  In the photo above, notice how the leafroller cut the Basswood leaf part way through and rolled up a section of the leaf into a nice tube.  The roll (or tube) has multiple layers and the caterpillar feeds on some of these while living within the sheltering roll.. 
The roll is held together with silk.  In the picture above, there are a few strands of silk visible in the upper left of the leaf shelter.
The leafroller even closes up the lower end of its shelter with very neat fold of the leaf..
Here is a photo of the Basswood Leafroller caterpillar.
Basswood Leafroller Moth Larva - Pantographa limata
After I unrolled the leaf shelter to take a picture of the caterpillar, it promptly went to work to make another one.
Make your own house in a jiffy, and eat it too...how cool is that?

Friday, August 26, 2011

Bladderwort

   Common Bladderworts (Utricularia macrorhiza) are floating carnivorous plants that lurk among the lilies in the lakes and ponds around here. For some reason, my old Peterson guide calls this plant the Greater Bladderwort, or Utricularia vulgaris,   I've also heard of bladderwort being called "popweed" for the popping sounds that the bladders makes when the plant is lifted out of the water.
    Much of year the bladderworts are inconspicuous, but they are more noticeable this time of year because their small yellow flowers are held up out of the water for all to see.
  Even so, the flowers are easy to miss.  I have canoed among the pond weed and lilies and suddenly noticed the bladderwort's flowers surrounding me.  Their abundance can be surprising.
The flower of the Common Bladderwort, Utricularia macrorhiza
 Even more surprising then those flowers are the bladderwort's tiny but sophisticated traps.  In the photo below a bladderwort is floating among the lilypads. Those numerous pouches are its high-speed suction traps.
 The free-floating, carnivorous Common Bladderwort, Utricularia macrorhiza
   The carnivorous bladderworts prey on zooplankton.  When an aquatic insect or some other small creature touches the trigger hairs, the trap's mechanism operates with incredible speed and sucks in the victim in less than a millisecond.


   Watch this amazing high-speed video of bladderwort's trap in action.
                            

Video credit: Philippe Marmottant.

With that impressive carnivorous action in mind, I can imagine what is happening in this photo.
   Just under the water's surface there is an extraordinary and secret world that has been made less obscure by high speed cameras and microscopes.
To me, the bladderwort's flower is an emblem of that hidden world.

   Doesn't the Common Bladderwort deserve a more spectacular name?  Even the names, Greater Bladderwort, or Popweed, are hardly descriptive enough.  Oh well, the name, like the bladderwort's inconspicuous flowers, can serve as a reminder of the carnivorous plant's incredible traps firing away just below the water's surface.

Tuesday, August 23, 2011

Ants Milking Honeydew From Locust Treehopper Nymphs

   Ants farm Black Locust Treehopper (Vanduzea arquata) nymphs on a Black Locust tree in my backyard. Ants farm the treehopper nymphs by herding and protecting them.  The ant's reward for tending the treehoppers is the honeydew secreted by nymphs.  Here are some photos and a video of the ants the "milking" the nymphs.
 
In both of these photos you can see the honeydew droplet secreted by the treehopper nymph.
Ant "milking" honeydew from a Black Locust Treehopper nymph

   In this video you can see the ants stroking the treehopper nymphs with their antennae and the nymphs responding by secreting a droplet of honeydew which is immediately taken up by the ant.  In other words, this video contains much antennae waving and some droplets of honeydew appearing and disappearing. The background noise is the buzzing of cicadas.

The tiny nymphs suck plant juices and honeydew is a sugary waste product.
The photo below shows a late instar of the treehopper.

Here is a picture of an adult Black Locust Treehopper.
Black Locust Treehopper, Vanduzea arquata
 The adult treehoppers are also tended by ants.
Ants tending Black Locust Treehoppers


   Just for the fun of it, here is a photo of another species of treehopper found on the same young Black Locust in my backyard..  This is the Locust Treehopper (Thelia bimaculata) which mimic thorns on the Locust trees.
The Locut Treehopper is a great thorn mimic

Actually if you look close at the photo you can see the male Locust Treehopper with a female one beside him.  On my other nature photo blog I posted separate photos of the male and female Locust Treehoppers.

Saturday, August 20, 2011

Poplar Tentmaker Moth

On July 4th weekend this Poplar Tentmaker Moth showed up at the porch light.  
The Poplar Tentmaker Moth, Clostera inclusa.   Also called the Angle-lined Prominent
  The Poplar Tentmaker Moth, Clostera inclusa, is also called the Angle-lined Prominent.  This moth sure is odd-looking, isn't it?  Without anything for scale in the photo it looks more like a Poodle or something.
 About a week later I noticed these eggs on a young Quaking Aspen in our backyard.
 I decided to keep my eyes on eggs and see what would develop. 
 In another week the eggs looked like this...
Eggs of the Poplar Tentmaker, Clostera inclusa
    Later I noticed feeding sign on the Aspen's leaves, but I didn't see any caterpillars.  I kept seeing more leaves being skeletonized, but I didn't see any caterpillars.  Then one day I must have been more observant because I noticed the dead-looking leaves on the end of the branch.  These leaves were sewn together with silk into a leaf shelter.
 This leaf shelter was constructed of a uniquely folded leaf, with the second leaf pulled over for some extra room.
Leaf shelter of the Polar Tentmaker
   This leaf shelter was sewn together by the Polar Tentmaker larvae as a place to hide during the day.  I took a peek inside.
Larvae of the Poplar Tentmaker, Clostera inclusa, hiding in their leaf shelter
  Isn't that leaf shelter a nifty contraption?  These gregarious (social) caterpillars grouped in their "tent" remind me of a gathering at a picnic pavilion.  Perhaps they are actually having a slumber party.
    I don't know what time of night the caterpillars head out for their munchies, but I was out late several evenings and saw no sign of them.  However, one morning before daylight I remembered to check on the larvae, and sure enough, I caught them in the act of feeding on the Aspen.
 I believe these two photos were taken at about 5:15am.
   I must have just caught those snacking caterpillars, because at that time, some of them were already headed back to camp.
  
  I was thrilled to see such a unique looking moth as the Poplar Tentmaker, and even more thrilled to have its larvae camping in a leaf shelter contraption here in my backyard.

Friday, August 19, 2011

Variegated Fritillary

   I first noticed this Variegated Fritillary on a Red Clover flowerhead, but she didn't give me a chance to take a picture.  Then I noticed the same butterfly flitting around the yard and briefly landing here and there.  I thought if I followed her those actions would give me some chances for good photos.  As I pursued the butterfly, I noticed that there was a pattern and purpose in her flitting around.
   Can you guess what the butterfly was doing?  Note her shadow on the violet leaf.
Variegated Fritillary, Euptoieta claudia, laying an egg on a violet leaf
 I observed her land on violet leaves and lay an egg or two.  The fritillary would fly around the yard about a foot off the ground and was obviously scouting for suitable egg-laying sites.

Here is a photo of one of the eggs the butterfly laid.
   I hope the eggs hatch before the lawn gets mowed, although another observation I made was the butterfly would select small or younger leaves on which to oviposit.  I staked out a violet patch with big obvious leaves, anticipating some easy close-up pictures, but she just flew over a few times and went on to other smaller leaves.  I'm not sure of the reason for selecting the smaller leaves, but that may unintentionally benefit the eggs by keeping them out of the mower's way.
Variegated Fritillary, Euptoieta claudia, ovipositing on a violet leaf
   The fritillary would occasionally land on a clover leaf or small dandelion leaf, but it would instantly leave.  From those observations I would guess the fritillary was using visual cues for locating the violet host plants.  Then upon landing, using chemical cues to verify if the leaf was the correct host plant and determine its suitability as a oviposition site.                                        
There is probably more to it than that, but needless to say, I was impressed with her host plant selection capabilities.
Ah yes, it was pleasant to observe and ponder the host plant locating abilities of the Variegated Fritillary.  Also, thanks to her egg-laying pauses, I had a few chances to take some tolerable photos.

Wednesday, August 17, 2011

Surprising Slug Slime

   When I found a slimy slug eating mushrooms in my backyard, I thought the slug would make a good homeschool science lesson.  You can use the slug for a great introduction to the interesting field of chemical ecology and for a gratifying demonstration of the slug's chemical defenses.
   The slug's slimy defensive mechanism can be demonstrated by gently poking the slug with a toothpick or similar object. This photo shows the results of a slight poke...nothing surprising.
Slug Slime Experiment

But, this photo shows what happens when you wiggle the "toothpick" like you are an ant trying to get a bite of the slug.
Activating A Slug's Chemical Defenses
When the slugs chemical defenses "kick in",  the slime instantly coagulates into a gummy mass (slug slime glue) which can gum up the jaws of the attacking predators.
   In the photo above, I glued the "toothpick" to a board with the slug's coagulated slime.  Instant slug slime glue is a rather surprising result from poking a slug, isn't it?
    I enjoy reading Thomas Eisner's books.  Here is a quote from his book "For Love Of Insects" on the slug slime subject.
   "Biorationality told me also that the slugs themselves had to be protected, and I found that they did indeed have a remarkable way of coping with the likes of ants. There is a simple experiment anyone can do to activate this defense. Look for a slug, and when you find it, poke it gently with a toothpick. A pine needle or leaf stalk will do as well. As long as you keep the stick motionless, nothing will happen. But if you wiggle the stick, the slug will set in motion a coagulation mechanism, whereby the slime in the immediate vicinity of the contact point is converted into a rubbery blob that clings to the tip of the stick. The mechanism is wonderfully effective because it keeps an enemy from piercing the body wall or the slug. Ants are literally muzzled when they bite into a slug. They are thwarted the moment they bear down with their mandibles, and as they back away, are left with their mouthparts encased in coagulated slime.
   I still don’t know how the mechanism works but I can imagine that some sort or coagulation or macromolecular cross-linking is involved. Dan Aneshansley and I have data based on the response of slugs to localized application of mild electrical stimuli that show the coagulation to be triggered in a fraction of a second—literally in less time than it takes an ant to clamp down with the mandibles. And we have learned that in some slugs the coagulation is accompanied by the visible injection of crystalline material into the slime from specialized integumental cells."     page 397
  For Love of Insects by Thomas Eisner 
  If you homeshool, and you take your science lessons down the slug slime trail, the slug's ingenious chemical defenses are just one of the many interesting stops along the way.

 Here is a link for a site that has some experiments you can do with slug slime glue.

Friday, August 12, 2011

Something Has Been Munching On My Mushrooms

There are these mushrooms growing in my backyard...
 I noticed something was eating them.  In the photo below, you can see the feeding sign on the lower part of the mushroom's stalk.
Who did it?
I had a strong hunch I would have to catch the culprit in the middle of the night.  That is why I was out at midnight the other night when I saw the crane fly I posted about yesterday.
Sure enough, I caught the midnight mushroom muncher in the act!
Slug Feeding On Mushroom
Those optical tentacles caught in the glare of the flashlight beam give the slug a "deer in the headlights look".  

Here is a photo of another slug feeding on a fallen mushroom.
Now I know I used the word "munching" when I should really have used "rasping" because a slug feeds by rasping with its radula.  Here is a radula diagram from wikipedia that nicely illustrates the radula in action.
Source Wikipedia 

You could say my slugs were feeding on fungus filings. 
Are radulae busy rasping in your back yard?

Homeschoolers, you could take your classroom to your backyard and learn alot from slimy slug "munching" on a mushroom.

You might also like my post about radula marks in algae.

Thursday, August 11, 2011

Crane Fly

   At midnight last night, I saw this crane fly hanging out in my back yard.  You can see some strange things in the middle of the night, like a crane fly hanging between two grass blades as if it were a hangingfly.  What was it doing? Waiting for the sunrise?  Maybe grass blades have just the right "springyness" for a good night's rest...not too hard, not too soft.
   I would have liked to see the crane fly bend those two grass blades into that arched position.  Perhaps it was winging along and caught hold of the one blade with its left legs, then did an about-face with its right legs flailing and swept in the other grass blade.
Crane Fly Acting Like A Hangingfly
  Crane flies are true flies.  That means they have only one pair of wings and a pair of halteres.  Fly's halteres function as part of their flight stabilization system...their gyroscopes.  One is plainly visible on the right side of the crane fly in the photo below.  See the little lollipop-looking thing between the wing and the V of the bottom two legs?
   It's a bit unusual for me to be out at midnight observing nature, but I sure did see some strange things. This crane fly was only one of them.  Another was a midnight mushroom muncher.