Saturday, September 29, 2012

What Lives In A Waterfall? Part III

   Net-spinning caddisfly larvae really like living on the edge... crowded up at the edge of the waterfall almost as if they rejoice in the noisy torrent of water rushing over their tiny nets.  Crowded... like people watching Niagara Falls.
  Net-spinning caddisfly larvae (Hydropsyche spp) spin fingernail-sized nets with underwater silk.  The fine mesh webs function as collectors, filtering food materials from the water such as FPOM (fine particulate organic matter) some of which originated from the leaves that fell into a stream.
 The nets are held upright and open with pieces of vegetation incorporated into the opening like tent poles.
Those "tent poles" are held in place with strands of silk acting as guy-wires. Think of the engineering abilities programed into these tiny larvae! 

I'm amazed how the small silk nets can stand there given the strong currents where they are erected. Wouldn't it be fun to watch a caddisfly larva spin its underwater web and erect those guyed poles?
 The net-spinning caddisfly larvae reside in the holes at the back of their nets.  They emerge from their silken retreats to tend to, and feed from their nets
 The larvae are not very pretty, but are well designed for their unique lifestyle.

In the photo below a caddisfly larva is tending its net (on the left).

   Here's a view looking straight down on a falls where the caddisfly larvae have spun their silk nets right on the very edge.  Interestingly, in this photo you can also see some caddisfly larvae tending their nets.   

Whenever I would place my underwater digital camera near enough to snap a close-up photo of the larvae they would back into the depths of their silk retreats.
   Personally, I think the silk nets add to the underwater scenery.
Incidentally, cities are often built at "falls".
   The net-spinning caddisfly larvae also populate the river's riffles... like so many tents in a busy campground.
 The caddisfly larvae love the swift water.
I started this series of posts asking the boys, "What lives in a waterfall?" 
I doubt they'll forget the crowds of silk nets at the falls and in the swift water.

See What Lives In a Waterfall? Part I
Also see  What Lives In a Waterfall? Part II
I make reference to these caddisfly larvae nets in "Under The Susquehanna".
Here is another underwater photo of the caddisfly nets.

Tuesday, September 25, 2012

What Lives In A Waterfall?, Part II

   In my last post I asked the boys, "What lives in a waterfall?"  Well, something does love to live on the very edge of waterfall's rock ledges.  Aquatic insects have staked out their claim at the very edge of the falls.
   These photos are taken with my underwater digital camera...  looking downstream at a falls.  The white, cloud-like pattern is the swift water going over the edge of the falls.
 Yes, those patterns are from the swift water... not the northern lights. 
What a spectacular place to live!
Consider too, the incredible abilities of these aquatic insects, living there in that constant, rushing current.
For one thing, they don't get a break.  If they let go... well, you get the picture.
Up next, a post about these waterfall-dwelling aquatic insects.

See also  What Lives In A Waterfall?  (part 1)
               Part III of  What lives in a waterfall?

You might enjoy taking your own underwater photos with an underwater digital camera... here's the one I used.

Monday, September 24, 2012

What lives in a waterfall?

I said to the boys, "Hey guys, what lives in a waterfall?"
You can see that captured their interest.
Now, that makes my day!
Of course, there's more than splashes and bubbles in a waterfall.
Y'all up for some splashin' around?
See, What Lives In A Waterfall?, Part II 
        What Lives In as Waterfall?, Part III

Friday, September 21, 2012

Giant Yellowjackets, Part II

   I walked past the Lilacs and was promptly surrounded by half-a-dozen buzzing, threatening hornets that looked like giant yellowjackets.  
    We found ourselves neighbors to a great number of these black and yellow hornets when we were visiting in southern Pa. last weekend.  I've never seen so many of these European Hornets in one place.   I suspect the hornets were plentiful in the row of Lilac bushes for two reasons... First, I'm fairly certain they had a nest nearby in a hollow part of an old Popular Tree. Secondly, the sap of the Lilacs is a major food source for them.
   These European Hornets are bright yellow with black markings, so over all, they resemble yellowjackets even with the reddish markings behind their eyes and around their wings.  The most outstanding visual difference between these hornets and yellowjackets is their size.
   I wanted a photo that showed the size of these hornets so in order to get one to stay put on my finger I offered the hornet some honey.  Well, it wasn't impressed with the honey and I almost got stung.
After that close call, I decided to take the safer route while trying to show the size of these large hornets, as you can see from the photo below.
The photo of the European Hornet shows this one is over an inch long. Notice the stinger.
Here is a photo of a European Hornet beside a yellowjacket.
   One notable thing about the European Hornets is their affinity for Lilac sap.  It's fascinating to watch these giant hornets chew away the Lilac's bark and feed on the leaking sap. 
The hornets were busy removing patches of bark from branches in the top of the bushes all the way down to the main stem.
All that chewing can really do some damage.  Especially if the hornets happen to chew on the bark all the way around, girdling the branch.  That would kill the branch beyond that spot.
   European Hornets were introduced to North America way back in the 1800's so they are nothing new. However, I've never been entertained by them like I was last weekend.  I've mostly seen lone ones patrolling here and there.
Back when I was young, there must not have been a nest of these hornets close to the Lilac bush along the barbed wire fence at Grandma's house... or I could probably tell you what their sting is like.

Monday, September 17, 2012

Giant Yellowjackets

Have you ever met these hornets that look like giant yellowjackets?  Here is a picture of one giving a Lilac branch a bear hug.
They sure love the branches of Lilac bushes... as evidenced by the photo above.
Stand by for more on these large black-and-yellow hornets.

Friday, September 14, 2012

Windsocks in the River

No, this underwater photo is not of my son meeting a water snake,

 but rather, the windsock-like catchnets of the tube-making caddisfly larvae I mentioned last post. The silk nets billow in the current, causing them to change shape now and then.
 The caddisfly larvae that weave these catchnets are commonly called trumpet-net caddisflies - referring to the trumpet-shaped nets with their tapering tubes and flared openings.
Many of these insect-sized fishing nets (if I may call them that) are fastened to rocks, woody debris, and vegetation in this section of the West Branch Susquehanna River.
   Trumpet-net caddisfly larvae (Neureclipsis) weave these recurved silk nets as a means of collecting food.
The gaping mouth of the net allows river water to enter and the silk net filters out detritus, plankton, and other organisms.  The larvae live in the silken retreat and subsist on the collected food particles.
   I'm impressed with the trumpet-net caddisflies.  For one reason, the quantities of underwater silk that they spin.  Another reason is how they weave these looped catchnets right in the current.  Thirdly, I'm impressed how the caddisflies set up shop with their nets and utilize the food resources that are just passing by on the current.
Above - a photo of a caddisfly net that is hung in the gap between two river cobbles.
Below - a collection of caddisfly nets hanging on vegetation and rocks.
  When I see these wide-mouthed monsters ravenously devouring the river, I wonder what percent of the river's water gets sieved?
By the abundance of these billowing nets, it's apparent that they do a whale of a good job sieving food particles from the river.
   Anyway... the river flows on...
What else can we find hidden under the water's surface?

Monday, September 10, 2012

Under The Susquehanna

We are drawn riverward as we explore the riparian habitat along the river here in Pennsylvania's scenic mountains.  Since we have our water shoes on, we'll wade out - and even dive - into this vast and enrapturing underwater world.

In water, under the swirling currents, there is a realm of aquatic life that we love to explore. 
Yes, it's a wonderful world - this water world - as it wends its way along from headwaters to the ocean.  Between the mountain streams and the bay there are may changes along the way.
   The West Branch Susquehanna River, right here at this location, seems almost devoid of life.  At least at first glance.  Actually, there is an abundance of a relatively few creatures (low biodiversity).  This is a result of a combination of physical and abiotic factors, such as acidity... and of course the tolerances of the aquatic creatures.
  Two of those abundant creatures are the aquatic insects are living on the rock shown in the photo below.
The most noticeable things on the rock are the "windsocks" billowing in the current. These silk nets are made by tube-making caddisfly larvae. These fairly large funnel-shaped, or bag-shaped, catch nets are spun and hung in the current to collect food particles/organisms on which the caddisfly larvae feed.
These particular tube-weaving caddisfly larvae prefer to set up shop by hanging out their "windsocks" in the gentler currents of the river.
   Another abundant inhabitant of this section of Susquehanna River are one kind of case-building caddisflies.  These caddisfly larvae are also filter-feeders. The river brings them their food... all they do is snag it. These caddisfly larvae collect food particles by holding their legs up into the current -  like the larva in the photo below (center right).  The larva are equipped with combs on their legs which collect fine particulate organic matter, FPOM.
These caddisfly cases are present on many of the rocks in our river.  They are more visible on the cobbles in the swift water.
Water shoes and snorkels anyone?
I'll post more about the windsock caddisflies and those tiny, trumpet-shaped cases on the rocks in the near future.  Oh, and notice the many tan "tents", or silk caddisfly nets, set up on the river bottom (photo above)... those are "way too cool" to pass up. I'll post about those as well.
Here is a previous post on aquatic life
What happens when a leaf falls into a stream

Wednesday, September 5, 2012

Yellow-eyed Grass and Three-hour Flowers

   I'm continuing to explore (by popular demand) the riparian habitat along our long, crooked river.   While in this lovely setting I have to ask myself, "What secrets are hidden by these hills?"
Of course, I also have to ask, "What lies hidden at my feet?"  Which means I didn't get very far exploring up or down the shoreline. I got hung up by the Yellow-eyed Grass.  
   I would call it a rare experience to see these tiny yellow flowers blooming among the sedges on the shore of the Susquehanna River.  One reason is, Yellow-eyed Grass is inconspicuous.  These diminutive flowers blend in well among the rushes, sedges, and nut-grasses.
   What caught my eye when I spotted this patch of Yellow-eyed Grass was the unusual, three-petaled flowers.  What's eye-catching is how the flower protrudes from the oval inflorescence which is perched on top of a long, slender stem.
   The name, Yellow-eyed Grass, can be misleading... it isn't truly a grass, even though its leaves resemble its namesake.  I believe the plant growing here is the Bog Yellow-eyed Grass - Xyris difformis.
   One remarkable thing about Yellow-eyed Grass is the flowers are open only very briefly. The flowers are here today and gone tomorrow. The flower in the picture below will soon close and fade like the flowers from other days... still hanging there, wilted, on the inflorescence.
 I was impressed with the brevity of their anthesis when I observed that the Yellow-eyed Grass flowers open late in the morning and a few short hours later they close.
The flower of the day simply fades away and another one will bloom the next day.  Here is a photo of a Yellow-eyed Grass flower.
Compare the picture above with the one below of an older inflorescence... notice its faded flowers from previous days.
Interestingly, a sheath envelops the flower bud as it emerges in the morning.  In the photo below I believe I  can see the shed sheath (clear and shiny) from this flower's morning opening.
The flowers do not produce nectar, but are pollinated by pollen-seeking bees and flower flies.  A late-summer pollen shop... open daily, but briefly  There is a flower fly visiting the tallest flower in the photo below.
Truly, these short-lived flowers are a rare beauty to behold.
  I like to think of them as "three-hour flowers".
   Well, the Yellow-eyed Grass flowers are closing up pollen shop for the day, so perhaps I'll move along and see what else lies hidden in plain sight along the Susquehanna's shoreline. What other discoveries are awaiting the riparian rambler?

   In light of these three-hour flowers, here's a bit of wisdom to ponder while down by the river.
As for man, his days are as grass: as the flower of the field, so he flourisheth. For the wind passeth over it, and it is gone; and the place thereof shall know it no more.  But the mercy of the Lord is from everlasting to everlasting... Psalm. 103:15-17a