Minnesota Naturalists Association

Insects like most multicellular life on this planet reproduce through sexual reproduction.  Simply put they exchange genetic information between two individuals.  This exchange of genetic information between two different individuals creates new genetic sequences that allows for the tremendous variation within a species and ultimately explains the diversity of life on the planet.  Species with more variation within the species will be more likely to produce offspring that will be suited for the environment.  This is not to say that every individual is best suited, quite the opposite, only a select few will have the opportunity to pass on their genes to the next generation.

The process described above is a simple idea to comprehend and is often called under the simplified term of Natural Selection; the mechanism of evolution.

Insects reproduce is very different ways that we are familiar with as mammals.  Many insects have very elaborate rituals to win mating rights.  Some even sacrifice their own lives for the simple opportunity to mate.  It may seem like a cruel world but the drive to pass on one’s genes to the next generation makes organisms (human or otherwise) do some extreme behavior.

Dragonflies have a rather unusual method of mating.  The male has claspers on the end of his abdomen that he uses to clasp onto the perspective female’s head.  This love grip allows the female to conjugate with the male using her elongated abdomen.  The position may seem odd but it allows the pair to maintain flight ability throughout the mating process.  Together they fly through the air avoiding the hazards that lurk by perching on the ground or vegetation.

The photo above clearly illustrates how the conjugated mating position allows for sufficient movement and clearance of both sets of wings.  I found this pair resting right outside my front door late last summer.

The photo above is a detail of the male claspers grasping the female by the head.  The morphology of the claspers prevents damage to the sensitive eyes of the female.  I think this could be the dragonfly equivalent of a hug.

When the mating is complete the female will visit a nearby water source where she will lay her fertilized eggs just below the surface of the water on aquatic vegetation or debris.  The eggs will hatch into tiny nymphs and will spend up to several years developing underwater before emerging as an adult dragonfly on a cool summer night.

I saw my last dragonfly of the season on November 7, 2011.  This was an extremely late date to see dragonflies flying around in central Minnesota!   Without flying insects to eat adult dragonflies ultimately succumb to the elements or loss of food.  Only those who were able to pass on their genes will influence the population of dragonflies the following summer.  Without sexual reproduction we would not have the tremendous diversity of life on this planet.  Without a diverse genetic library within a species there cannot be success for that species no matter where it lives.  Without the variation it is genetically destine for extinction.  That genetic threshold is difficult to identify and depends largely on the species.   One must ask themselves if many of our “endangered species” are already effectively extinct from a genetic perspective.  Loss of a single individual can have dramatic effects in a small population from a genetic perspective.

What is the purpose of conservation?  Are we conserving the world for humans or for all life?

The social upheaval in the United State of the 1960′s is sometimes summed up with the catchy phrase “flower power”.  What this really means is lost someplace deep the mind of an original hippie somewhere.  Flowers are the reproductive parts of a the plant, understanding this basic botanical anatomy changes the meaning of the phrase quite drastically.   No matter what it means the phrase has become a symbol of the social and environmental movements started, largely, in the 1960′s.

Flowers are serve as an oasis for many species of insects.  Their plentiful nectar is reserved only for those that have the right tools to get it.  Some present their good quite flamboyantly, other are much more subtle.  Like my previous post Spider Sniper details flowers also attract a variety of predators to take advantage of the bountiful prey.

Like the watering hole in the drought stricken African Savannah, predators of all types flock toward flowers with the simple knowledge that eventually their prey will have to come to them.   My previous post detailed how the crab spider sits patiently for its prey, but there are larger predators out there…

As the old adage goes “There is always a larger fish in the pond”, so too does this statement ring true with every other ecosystem on earth.  Every predator must be on guard because it is also prey.  The predatory crab spider from Spider Sniper would be a crunchy morsel for this young tree frog.  The tree frogs invade my flower garden each summer to feast on the plethora of invertebrates that have come to garden to feed (on the flowers or other invertebrates).   A keen eye can spot a frog on nearly every plant, patiently waiting for its prey to make an appearance.

Tree Frogs may be the top predator of the plant or the leaf but they certainly do not own the garden.  They must avoid becoming prey for snakes, birds, weasels, shrews and a myriad of other predators.

Tree Frogs can change color from gray to green to match the color of their background, and hopefully avoid detection by predators.

This young frog recently emerged as an adult from the vernal pool just feet behind my garden.  It’s head still looks more like a tadpole than an adult frog and there is still a little vestigial tail from its days as an aquatic larvae.

Now this frog might look like I posed it for the shot, but I assure you this is where I found this particular frog.  It is one of those moments that is just too perfect to pass up.  A tiny frog sitting on the head of a dew covered daisy.  (cue the “AAWWWW”)

I really like the one above,  you can see the Bee Balm just out of focus in the back.

Here the little frog waits for its invertebrate prey.  The carnage of the struggle for life happening in my own peaceful garden.  If “flower power” is supposed to make a call for peace and tranquility, then those individuals who chant the call have never truly witnessed the simple struggle for survival that occurs in every garden around the world.  Nature is not peaceful, or tranquil despite the delicate appearance.  Nature is a gloves off fight to the death and only the victors live to see another dawn, “Flower Power” indeed.

Spiders are among the most primitive of all terrestrial predators.  Not long after insects first invaded the land the primitive ancestors of modern spiders followed to gorge themselves on the newly invaded soil.  Today spiders still hunt their insect prey as they did millions of year ago.  The technique used to capture their prey varies widely and is even specific to a particular species.  The classic example is spider’s webs.  A silken web of sticky strings that capture prey in a tangled coffin.  Although all spiders have the capacity to make silk not all spiders build webs.  Some spiders are active hunters,  the wolf spiders, jumping spiders, and crab spider are all predators on the foot.  They stealthy stalk their prey and attack with vicious speed and agility.  They are true predators in every sense of the word.

Because spiders have an extremely low metabolism they have the uncanny ability to wait.  They can go day or even weeks without eating, simply waiting for their prey to make a fatal error.  Crab spiders are among those species who do not build webs but rather wait for their prey to come to them.

I found this large, perfectly white, crab spider perched on a large daisy in one of my backyard gardens.  It sat motionless waiting for an unsuspecting pollinator to land for a quick meal.  Crab spiders get their name from the way they hold their legs out stretched, much like a crab.  Unlike a crab these spiders do not walk sideways, their legs are out stretched like a foot trap waiting to spring.

If an unsuspecting pollinator does land on this particularly deadly daisy the spider’s trap will be sprung.  In the blink of an eye the spider’s forelimbs will spring forward and snare its prey delivering a fatal bite from the spider’s fangs.  If there ever were an arachnid equivalent to a military sniper this it.

Even the spider’s eyes are adapted for ideal vision and ranging.  It’s large binocular vision allows it to perceive motion and distance with deadly accuracy.  Even on this minute scale the adaptation for binocular vision in predators is very apparent (large predators typically have their eyes in the front to allow for accurate interpretation of motion and distance, think lions, eagles, wolves, and even people!).

Even the most serene of places has a never ending struggle between life and death occurring just out of sight.  The battle is not invisible but is only view by those with a curious eye.  Next time you see a spider, stop and ask yourself what it is really up to.  Is just aimlessly walking around or is it out on the hunt!

November in the Upper Midwest is a time of seasonal purgatory, the colors of fall are decomposing on the forest floor, the summer residents are well south of their local summer stomping grounds, the woods seem uncomfortably silent, as if they are still coping with the loss of its seasonal residents.  Minnesota becomes a land of brown and bland.  There is no green of summer or pure white of winter, it is Mother Nature’s way of saying “BLAH”.

Reviewing my photographs from last summer I found a file full of photos that had remained untouched since I took them this summer.  My next several posts will be a reminder of the difference a few months can make here in the great state of Minnesota.

A juvenile grasshopper basks on the petals of a cone flower in the morning light.  Grasshoppers go through a process of incomplete metamorphosis.  This means that, even in their juveniles stages, they look very similar to the adult.  Grasshoppers over winter as eggs laid in late summer.  When they hatch in early spring, miniature grasshoppers emerge and grow throughout summer until they are fully matured adults ready to pass on their genes for the next generation.  Think of this like the opposite of butterflies, flies, bees, and most other insects that go through complete metamorphosis, where the larval and pupal stages look nothing like the adult (think caterpillar and butterfly).

The landscape is brown and bleak now in November, but I cannot help but think of all the hundreds of thousands of eggs of a myriad of insects that lay in wait for next spring.

A small fly takes a break on a leaf.  Note the amazing iridescent color on the thorax.

Bumblebees, unlike the grasshoppers do not overwinter as eggs.  Rather only the queen overwinters.  She was hatched late in summer and traveled out of nest to find a place to overwinter.  Come spring she will be among the first flying insects to fly, often while snow is still on the ground.   Early blooming plants and trees will fuel her establishment of a new colony of up to a hundred or so bees (depending on the species).

Although the colors of fall may seem like all life as disappeared from the land remember all of those forgotten year round residents that are simply waiting for the appropriate conditions to recolonize the land.

Up Next:  Frogs and Flowers

October is a time of change for all ecosystems here in Minnesota.  The summer visitors begin migrating south lands of eternal warmth.  Many of the year round residents who are unable to flee the approaching frosts are forced to adapt to the cold or simply wait it out until the following spring.  A vast majority of species choose the latter, with only the heartiest species staying active throughout the long northern winter.

October signals the deciduous trees to drop their leaves, squirrels to create caches of food to last through winter and animal of all kinds to find shelter.  Frogs are no exception to this rule, the must find a place to over-winter or risk never rising from their slumber.  Unlike many other animals frogs, specifically tree frogs, have the amazing ability to freeze completely solid.

The Eastern Gray Tree Frog (Hyla versicolor) is a common tree frog throughout much of Minnesota.  They spend a majority of their lives away from water in forested areas.  They return to vernal pool in late spring until the beginning of July.  They spend the long winter underneath the leaf litter of the forest floor frozen completely solid.   This is no small feat for a complex vertebrate, in fact they are among a very few vertebrates who can tolerate being frozen solid.

Tree Frogs perform this amazing feat by literally turning their blood into antifreeze.  They increase the sugar content of their blood to such a degree that as the temperature falls the water in their blood is unable to form destructive crystals.  The frog simply freezes solid without the formation of any water crystals that act like microscopic knives cutting through tissue.  Humans call this formation of ice in the body frost bite.  Severe frost bite can result in complete necrosis of the affected area.  Frogs bypass these effects by putting themselves into the equivalent of a diabetic coma.

Eastern Gray Tree Frogs are among my favorite of all frog species in Minnesota.  They are amazing not only for their ability to freeze solid but also change color.  As the name suggests they are often “gray” but they can also change to a bright green as they transition between bark and leaves.  In addition to changing color that can change the texture of their skin, all be to a lesser degree, to match their surroundings.

These unique abilities of this frog species allows them to inhabit everything from the forest floor to the tops of the trees.  This diverse habitat allows them to exploit a wide variety of insects to feed on.

It may not look like effective camouflage close up but placed in a more natural habitat it serves its purpose quite well.

Did you find the frog?

Next time you take a mid-winter hike through a snowy wonderland think about all the thousands of insects, frogs, and plants that are patiently waiting in a dormant state for the first sign of spring.

October is a time of change for all ecosystems here in Minnesota.  The summer visitors begin migrating south lands of eternal warmth.  Many of the year round residents who are unable to flee the approaching frosts are forced to adapt to the cold or simply wait it out until the following spring.  A vast majority of species choose the latter, with only the heartiest species staying active throughout the long northern winter.

October signals the deciduous trees to drop their leaves, squirrels to create caches of food to last through winter and animal of all kinds to find shelter.  Frogs are no exception to this rule, the must find a place to over-winter or risk never rising from their slumber.  Unlike many other animals frogs, specifically tree frogs, have the amazing ability to freeze completely solid.

The Eastern Gray Tree Frog (Hyla versicolor) is a common tree frog throughout much of Minnesota.  They spend a majority of their lives away from water in forested areas.  They return to vernal pool in late spring until the beginning of July.  They spend the long winter underneath the leaf litter of the forest floor frozen completely solid.   This is no small feat for a complex vertebrate, in fact they are among a very few vertebrates who can tolerate being frozen solid.

Tree Frogs perform this amazing feat by literally turning their blood into antifreeze.  They increase the sugar content of their blood to such a degree that as the temperature falls the water in their blood is unable to form destructive crystals.  The frog simply freezes solid without the formation of any water crystals that act like microscopic knives cutting through tissue.  Humans call this formation of ice in the body frost bite.  Severe frost bite can result in complete necrosis of the affected area.  Frogs bypass these effects by putting themselves into the equivalent of a diabetic coma.

Eastern Gray Tree Frogs are among my favorite of all frog species in Minnesota.  They are amazing not only for their ability to freeze solid but also change color.  As the name suggests they are often “gray” but they can also change to a bright green as they transition between bark and leaves.  In addition to changing color that can change the texture of their skin, all be to a lesser degree, to match their surroundings.

These unique abilities of this frog species allows them to inhabit everything from the forest floor to the tops of the trees.  This diverse habitat allows them to exploit a wide variety of insects to feed on.

It may not look like effective camouflage close up but placed in a more natural habitat it serves its purpose quite well.

Did you find the frog?

Next time you take a mid-winter hike through a snowy wonderland think about all the thousands of insects, frogs, and plants that are patiently waiting in a dormant state for the first sign of spring.

Controlling fire is one of thing that makes humans very different from the rest of the animal kingdom.  We have harnessed the constructive and destructive powers of fire and used it for thousands of years.  We have used it to clear areas to attract game, we have used it to forge weapons and we have used it to warm the spirit on cool winter nights. 

What is fire?  What is energy?  The second question is one I recently asked my freshmen biology class.  They began listing many different forms of energy but nobody could really put their finger on what energy really is.  Einstein once stated that “Energy cannot be created or destroyed, but can only change in form”.  This statement again alludes to the different forms of energy but does not give us a good idea of what it actually is!

Fire in the simplest terms is the light (a form of energy) and heat (another form of energy) release from the combustion of a given material, in this case maple logs.  The light and heat is released as the wood is combusted.  But where did the energy start?

To figure out where the energy from fire comes from we need to look at what is being combusted.  In this case it is wood from recently felled maple trees.  Maples are plants and therefore collect all of their energy through the process of photosynthesis.  As plants the use light energy from the sun to convert Carbon Dioxide and Water into Glucose (sugar) and Oxygen.   The energy is not “used” per say, but merely transferred into the chemical bonds within the Glucose molecule.

The Glucose produced from Photosynthesis is used to create the structures of the plant.  Cellulose is a polymer (long chain) of Glucose molecules.  Starch, another polymer of Glucose, is used as the plant’s food source (humans also love to eat plant starch!).  That simple Glucose molecule itself is broken down releasing energy used to create other complex molecules.

The plant stores all that captured energy within its chemical bonds.  Some of the energy is lost through each transfer.  The lost energy is returned to the universe.  Entropy is a measure of randomness.  As the energy leaves the plant at each step of transfer it is said to have higher entropy, or more randomness.  This idea of entropy is not easy to think about, but it helps explain how the natural world functions and even how we fit into the ecosystem of Earth.

Next time you sit at a fire and enjoy the heat an light on a cool autumn night take a moment to reflect on how it got there.  You are witnessing entropy in action.  The energy that originally came from the sun is now being released back into the universe.  It’s path on this planet is complete. Entropy has the final say. 

Up Next:  October Frog