Nature Walk #4.1 – Arthropods
Spring is Here!
Days like these remind me what I love so much about the South...warm Springs exploding with life.
This edition of my series of Nature Walks is a big one. I took all of the following images over the past few days - some on my lunch break, some at the NIEHS campus, some at home, and some simply next to the road on my daily commute. So perhaps "Nature Walk" is a misnomer for this edition, but it suffices. Even while staring at the lake through my windows at work I am walking nature in my mind (unless I'm sectioning brains).
I've broken this post up into four parts due to the large number of images:
- 4.1 - Arthropods (this post)
- 4.2 - Birds
- 4.3 - Reptiles, Amphibians, & Mammals
- 4.4 - Plants & Fungi
The images are highly compressed for bandwidth's sake, but you can click on the images for larger versions (and a few are much deserving of an extra click).
As always feel free to give me any species identifications where I have failed to do so or done so incorrectly.
Arthropods
The first thing I'd like to note is that if you haven't visited Bugguide.net before, you should check it out. It is an utterly indispensable online reference for everything arthropod. I almost never fail to identify insects using it (and it has quite a few experts and educated amateur entomologists always willing to help in identification).
My wife walked into the house white-faced a couple of days ago. She had gone into my shed for a tool. This is what she saw:
Dolomedes tenebrosus spider
"Go ahead - touch me - I dare you"
Dolomedes tenebrosus spider
It's a Dolomedes tenebrosus spider. She's a lovely beast. She keeps my shed relatively bug-free.
I saw this next spider at the pond back behind my property today. It's a Six-Spotted Fishing Spider (Dolomedes triton). Interestingly, I learned that it is of the same genus as the monster above, though they are massively different in size, color, habit, and habitat. They both belong to the family of Fishing Spiders (though the first one does not live on water).
Dolomedes triton spider
Dolomedes triton spider
While turning over some leaves, I found this brilliantly colored orb-weaver, (I believe it's a Marbled Orbweaver (Araneus marmoreus)).
Marbled Orbweaver (Araneus marmoreus)
At lunch I struggled to capture an image of this stunning beauty of a Coleopteran. It would sit still as I focused, then dart about a foot forward in a blink - I would move, refocus - rinse and repeat... It's a Six-Spotted Tiger Beetle (Cicindela sexguttata). What luck! Two different species with "Six-spotted" in the common name (the beetle and the spider above).
Spotted Tiger Beetle (Cicindela sexguttata)
Spotted Tiger Beetle (Cicindela sexguttata)
Of course, the Azaleas are in full bloom at the homestead, and are of course covered in bees, flies, and butterflies.
Here's a Eastern Tiger Swallowtail (Papilio glaucus).
Eastern Tiger Swallowtail (Papilio glaucus)
Next is the Eastern Carpenter Bee (Xylocopa virginica). I know they are carpenter bees because they drill into my wood-paneled house. This is followed by hungry red-bellied woodpeckers drilling into said wood to retrieve the hymenopteran snacks. This is followed by me patching and repainting the woodpeckers' hack job. It's a semi-circle of life.
(Note: If you haven't seen it, you must check out my story from earlier today: The Carpenter Bee and Her Mate: A Heartwarming (and Dissapointing) Tale of Rescue.
Eastern Carpenter Bee (Xylocopa virginica)
A bee (Anthophila (Apoidea) - Bees) of unknown identity (I couldn't even peg it to a family - help please? It was about half the size of the carpenter bees.
Unknown Bee
And some Ants (Formicidae) on a flower. I didn't even realize they were there until I checked out the image on my computer. It was a tiny flower.
Unknown Ants
Finally, I found a nice specimen of what I believe is a Carolina Mantis (Stagmomantis carolina) ootheca (egg case).
Carolina Mantis (Stagmomantis carolina)
Carolina Mantis (Stagmomantis carolina)
See the rest of this Nature Walk:
- 4.1 - Arthropods (this post)
- 4.2 - Birds
- 4.3 - Reptiles, Amphibians, & Mammals
- 4.4 - Plants & Fungi
The Carpenter Bee and Her Mate
Today I witnessed (and was an integral part of) one of the strangest and coolest insect-related events I've been privy to.
My wife and I are trying to get our home fixed up to be put on the market. One of the things we will be doing is repainting our front porch. Unfortunately, our porch is riddled with holes under the edge (that are invisible because of their positions). The holes themselves aren't a major problem, though appraisers certainly take note of them.
You see, the holes are caused by the Eastern Carpenter Bee (Xylocopa virginica). We live in the woods and hundreds of them buzz around me daily. They're actually pretty cute and are quite important pollinators. The trouble comes when woodpeckers, mostly Red-bellied Woodpecker (Melanerpes carolinus), take note of them and destroy the wood to get at the tasty bees and their offspring within the bees' tunnels.
So this morning, after watching a bee exit the hole (I initially thought it was a male but now I know it was a female), I promptly sealed the hole with putty thinking the problem was solved. I felt a little bit bad that all the bee's excavation work had been for nothing - but what could I do? Holes in my house structure are not a good thing.
Two hours passed.
I stepped out onto my porch and saw the bee again. This time however, she was frantically chewing at the wood above the bore tunnel (the entrances are always on the underside of the wood). In fact, she had already dug a hole large enough to stick her head through.
Then I noticed that there was another bee inside the burrow. I could see his little head staring upwards from the new hole (I now know that males have a characteristic white face).
I had sealed in the bee's mate!!
The bee kept sticking her head into the hole, followed by a strange buzzy chatter between the two bees. She kept trying to climb in but she hadn't made the hole big enough yet.
Eastern Carpenter Bee attempting a daring rescue
"Don't worry, Bjorn! I'll get you out!"
You must check out the video.
At this point I thought "Well, I sealed in her man, she thwarted my big-brained attempt at sealing the wood, and it's clear that she desperately wants back in - I might as well help a bee out."
So I grabbed my pliers, shooed her away from the hole, and widened it enough for her to fit through. She immediately went straight inside, after which there was much buzzy rejoicing (at least that's my own anthropomorphic imagining of what all the buzzing meant).
I ripped the hole wider with pliers and in she went.
I didn't really expect a rescue with the both of them exiting into the sunset to find a new home. I fully expected them to resume normal life (though it was still a rescue). In fact, I decided that since I don't really need to seal the hole right now, and since the bee had shown an amazing dedication to her mate (or more likely, her brood), I'd let them get through their rites of spring.
My wife witnessed the whole thing and felt bad for the bee as well, so she was happy to let them keep their home a little while longer.
But as I said, I really don't know much about carpenter bees. So a little research was in order. I found two excellent websites on carpenter bee life cycles and habits: One at Penn State and one at Ohio State. From these sites I learned a few details that made my plan a bit moot.
About the Eastern Carpenter Bee
First of all, unlike social bees such as bumblebees and honeybees, carpenter bees are much less social. A male and female pair up, the female excavates the burrow, and the male hovers around the burrow defending their territory.
The defense of the home is actually quite entertaining to watch. Every few minutes one (or sometimes several) bees will come near the nest. The diligent male immediately locks into a hurtling, writhing ball with the other males while making a loud ruckus, and chases them away.
This explains why I had only seen the one bee actually enter the nest. The female remains mostly inside the nest, though I must have happened to catch them while he was in and she was out.
Second, after the female excavates the entrance, she makes a 90 degree turn and continues the tunnel along the wood grain. After completing her tunnel, she deposits eggs (along with a food ball) one-by-one inside the burrow, sealing each "brood chamber" behind her. The chambers are collectively termed a "gallery."
Unfortunately, much like other insects, cephalopods, and many other animals, the female dies shortly after laying her eggs. So she is a goner no matter what I do.
The eggs that she lays then take about seven weeks to reach adulthood. However, they don't emerge from the burrow until August! They collect pollen and store it inside the galleries, and hibernate inside throughout the winter. In the spring, they emerge again to begin their own life as mating adult bees.
One thing I am certain of is that I can't wait until August to seal the holes - and even if I did I would probably just be dooming the new adults to a cold wintry death. So really, my entire altruistic idea is a moot point. I'm not really sure what I'm gonna do about them now.
Obviously, they are "just" insects. I'm certainly no St. Francis of Assissi1 or Ko Hung2. That being said, I don't generally enjoy killing anything unnecessarily. As I said before, we are surrounded by carpenter bees - our woods provide ample habitat - so I certainly won't be hurting the population.
Most people just shoot pesticides into the nests. I, however, refuse to use pesticides on my property (partly because we are on well water). I guess I could just try to seal it again, though I imagine they will find a way back in (or out).
What do you think I should do?
A couple of other points
Male carpenter bees cannot sting (males are distinguished by a white face - see image below).
Females can sting (but you basically have to handle them before they will).
Carpenter bees at my house buzz me constantly, hover in my face, land on me - but I have never once seen one act aggressive, even if I bat them to get out of my face. They are mainly just curious and very gentle creatures.
Male:
Eastern carpenter bee male showing large eyes, white face and mouthparts (image via Wikipedia)
Footnotes
- "Not to hurt our humble brethren (the animals) is our first duty to them, but to stop there is not enough. We have a higher mission--to be of service to them whenever they require it... If you have men who will exclude any of God's creatures from the shelter of compassion and pity, you will have men who will deal likewise with their fellow men." - St. Francis of Assissi
- "Respect the old and cherish the young. Even insects, grass and trees you must not hurt”. T’ai-shang kan-ying p’ien, a Confucian-Taoist treatise. Attributed to Ko Hung"
Adaptation of the Week – the Insect Dorsal Ocelli
Dog Day Cicada (wikipedia commons)
There's one particular event of every summer in the South that I always await with great anticipation: the emergence of the millions of annual Dog Day cicadas (Tibicen canicularis).
It's not just the event itself that I love. The cicadas are certainly wonders in themselves; but for me, they are more than just insects of the order Homoptera - they are the standard-bearers of my favorite time of year: the "dog days" of summer. It's the time of year when the sun shines the brightest, heat covers the land as lazy dogs curl in cool digs in the shade, and Sirius - the Dog Star and the brightest in the sky - makes its appearance above the Southern horizon.
Spring is nice. Fall is fairly beautiful. Winter could be thrown to the dogs and I wouldn't bat an eye. But Summer? Ahh, summer is the incubator of my soul. When I'm in it, the warmth makes my happiness grow as ideas sprout from the imaginal discs of my imagination.
It is in no small part the fact that cicadas choose late summer to burst newly reformed into the world, leaving their former larval stages behind, that they receive my respect. I like their style.
But they deserve my awe for many other reasons beyond our shared love of summer. Many of us are well aware of the cicadas' prolonged existence as grubs feeding amongst the roots of trees for years, the exact time dependent on the particular species. Many species have synchronized both their development and life-cycles to such a degree that they burst forth from the ground all at once after 13 or 17 years of sucking sap as larvae. They enjoy an incredibly short adulthood, frantically mating for a few weeks, followed by death en masse (much like the death orgies of the market squid).
The advanced life-cycle adaptations of the cicadas and the timing thereof are deserving of their own tribute. However, the focus of this article lies elsewhere in our cicadan wonders. For the cicada contains an organ prevalent among many orders of insects that many of you have likely never even heard of: the "dorsal ocelli".
"There are no more other worlds to conquer!" - Alexander the Cicada
"Did I play my role well? If so, then applause, because the comedy is finished!" - Cicadan Emperor Augustus
Dorsal Ocelli
I took the images above last summer after the poor (or perhaps ecstatically happy) little cicada had already performed its life duties. Shortly after emerging and mating, cicadas slowly become lethargic, then immobile, and finally they simply die. This individual had reached the immobile stage. It was still alive when these pictures were taken, but days later it had died - remaining in the exact same location and position you see it in now.
Now, look more closely. You may notice its head is bejeweled with three orange organs. These are its dorsal ocelli (singular: ocellus).
"It is during our darkest moments that we must focus to see the light." - Cicada Benson
The ocellus is a strange and still quite mysterious organ. It is present throughout the insect world, but only erratically. Despite their ongoing mystery, the organs have been studied fairly extensively since the 1920s and 30s. The following distribution of ocelli among the insects (for you entomologists) is from The Function of the Insect Ocellus1, by D. A. Parry in 1947:
ORTHOPTERA : always present in Acriidae and Gryllidae; sometimes present in Blattidae, Mantidae, Tettigoniidae; not present in Grylloblattidae. DERMAPTERA : absent. PLECOPTERA : two or three present. ISOPTERA: present. EMBIOPTERA: absent. PSOCOPTERA: sometimes present. ANOPLURA: absent. EPHEMEROPTERA: present. ODONATA: usually present. THYSANOPTERA: present. HEMIPTERA: great variation. Some families separated on the presence or absence of ocelli. Several families in which some genera possess ocelli and some do not. NEUROPTERA: conspicuous in some families, absent in others. MECOPTERA: some genera with ocelli, others without. TRICHOPTERA: some families with ocelli, others without. One family including six genera with ocelli and two without. LEPIDOPTERA: sometimes present. COLEOPTERA : absent except in a few species not all in the same family. STREPSIPTERA : absent. HYMENOPTERA: usually present, but sometimes absent in the Vespoidea. DIPTERA: sometimes present. APHANIPTERA: uncertain.
Many species it seems have found great use in the ocellus, as evidenced by its retention throughout much of the Insecta class, while others have completely disposed of it.
But what is it?
“If the sight of the blue skies fills you with joy, if a blade of grass springing up in the fields has power to move you, if the simple things in nature have a message you understand, Rejoice, for your soul is alive.” - Eleanora Cicada
Essentially, the dorsal ocellus is an eye. But dorsal ocelli are not like the large compound eyes always present nearby. Nor are they like our own.
Early studies measuring the focal depth of various ocelli lenses all came to the conclusion that ocelli cannot focus forms on their simple retinas. It has since been shown that this is mostly true, except with some dragonflies which apparently may be able to form images with their ocelli.
What dorsal ocelli can do quite well is sense light. In fact they are much more sensitive to light intensity than the main compound eyes.
Studies in the 40s showed that ocelli nerve impulses were inhibited by light. When the ocellus was occluded, signals would then propogate down the large nerves to ganglia. Essentially, if a shadow passed over the ocellus, signals fired. And because the nerves are very large in diameter (often the largest nerve fibers), they are very fast.
It was additionally shown that light perception in the ocelli alone could not lead to reflexive movement. Thus it was suggested, and some still hold, that light perception (or shadow perception) acts to set the excitatory potential of the nervous system. Thus, if a shadow passes overhead, the nervous system would be primed to react to visual stimuli from the compound eyes.
Advances in Insect Physiology
More recent studies have shown that ocelli are intricately involved in orientiation to light (including UV), particularly to the horizon, and so are integral parts of the flight stabilization machinery, which makes sense when considering that most flying insects have ocelli.
Again, research in dragonflies indicate that the ocelli can form images with very wide fields, and can sense motion. There are other indications that ocelli may play a role in circadian entraining.
To my knowledge, no physiological research has been conducted on the cicada ocelli. Regardless, it appears that whatever the function of the ocellus, it is intricately and physically intertwined with the circuitry of vision from the compound eyes.
The ocellus represents just one more example - among myriads - of a sense that we as humans can hardly fathom. It is hard enough to imagine perceiving the world through thousands of individual ommatidia (the many eyes within a single insect compound eye). Add to that a complex system of light perception wired to the eye circuitry to aid in orientation, flight stability, or to prime the brain for visual stimuli. Such perception is impossible to even imagine.
It's clear from my limited research that science has yet to fully explain the purpose of these beautiful adaptations, despite the prevalence of their existence. It just goes to show that we have not come close to deciphering all the mysteries of life - even mysteries that have stared us in the face for a century.
So this summer, as the cicadas raise their eyes and dorsal ocelli to the summer sun for the first and last time, take a second to give them a closer look. You may just find yourself in awe of these photosensitive jewels.
References
- Parry D.A. (1947) The Function of the Insect Ocellus. Journal of Experimental Biology. Vol. 24. Nos. 3 & 4. pp. 211-219 (pdf)
- Beament J.W. L. (1966) Treherne J.E. Advances in Insect Physiology. Academic Press. (book)
- Berry R.P., Stange G., Warrant E.J. Form vision in the insect dorsal ocelli: An anatomical and optical analysis of the dragonfly median ocellus. Vision Research. Volume 47, Issue 10, May 2007, pp. 1394-1409.
- Simple eyes in Arthropods. Wikipedia.org
Previous Adaptations of the Week:
Under the Sea 3D – A Stellar Review
Under the Sea 3D
This weekend my wonderful wife arranged a date night for us. And how awesome does it make her that it consisted of the single most breathtaking documentary I've ever seen - "Under the Sea 3D," a stroll through the evolution of life at the NC Museum of Natural Sciences, followed by a heaping plate of crab legs at the 42nd St. Oyster Bar in Raleigh? (no the irony of that last part is not lost on me - but hey - I loves me some crab legs!)
This post is both a review and a shout out to everyone who has not seen "Under the Sea 3D" at your nearest IMAX to immediately drop what you are doing and go watch it (check out its nifty flash site as well).
I'm not being overly hyperbolic here - this film (directed by Howard Hall) is utterly stunning.
There is basically no narrative in this film. But for what it wants to accomplish, I don't think any documentary I've watched has achieved its goal so succinctly.
The film begins with nothing more than sequence after sequence of mesmerizing coral reef habitats and creatures. It's narrated by Jim Carrey (who is great - I found myself forgetting that it was even him most of the time - there were no characteristic Carrey antics here).
But the key to this film is in the fact that the footage itself leaves you begging for more. Everyone in the theater watched in wonder - their mouths forced open by the alien creatures - usually only realizing later that they've been slack-jawed like goons for five minutes. The three dimensionality is pulled off to such a great extent that the creatures seem like they are moving and living mere inches from your face. I have never been scuba diving (and can't due to my marine unworthy inner ear), but I have been snorkeling - and I consider it one of the most amazing experiences of my life. That being said, the detail in this film far exceeded any real-life ocean experience I've had.
Each of the reef scenes is so filled with action - shrimp scuttling in the background, various fish doing their things, corals waxing and waning in the current - that you literally will want to watch it again just to focus on different aspects of each scene (not to mention the fact that the IMAX screen fills your entire field of view - it's impossible to see it all in one sitting).
Aside from the imagery which is hands down among the best I've seen, the conservation message is presented in the absolutely perfect way for its target audience (basically - everyone in the world and especially kids or the uneducated). Conservation or the ills facing the marine world are not even mentioned until your mind has been boggled by the crazy critters of the sea.
Only after bringing you into a state of constant awe does Jim Carrey begin hinting that things aren't alright. The message ramps up to the inevitable images of dead reefs, bleached by ocean acidification. However, I don't think it ever became overly preachy.
Under the Sea 3D
In fact the conservation message ended on an overly optimistic high note (overly from a scientific perspective) but one necessary if we ever want the general populace to care. Basically it paints the current state of the conservation movement as a hopeful paradigm shift in human society. It plainly states that humankind is beginning to realize its mistakes and that most people are coming around. Whether or not this is true is irrelevant because it leaves you thinking "hey, caring about CO2 and the oceans and biodiversity is the normal smart thing now. I want to be part of the informed and enlightened crowd. I want to care too."
In other words it doesn't just say "The oceans are screwed. It's all our fault. We should all be ashamed of what we've done." It says "the better angels of human nature are trying to turn it all around. And they are giving the world hope." And because of the tone, one cannot help but naturally want to be one of those better angels.
For you marine biologists, the very simple message will seem quaint. But I'm sure you will understand the necessity of this sort of film serving as an initiator for conservationist thinking.
I honestly believe that every person on the planet should watch this film. Especially the children.
Oh, and did I mention that there are TONS of cuttlefish in it?
Don't even think for half a second that the following trailer comes close to doing the 3D beauty justice!
Tentacular Orgies from The Oyster’s Garter
Squid Larva (from squidblog.net)
Here's a big congratulations to Miriam Goldstein of The Oyster's Garter fame, who managed to get a truly fascination article published on Slate.com.
Her article, entitled "Motion in the Ocean" is all about the Valentine woo-pitching (quote: "making the beast with two beaks") of squids off the California coast. I highly recommend the read, and be sure to check out the linked videos from the article as well!
And since I'm doling out the link love, I'd like to welcome the newest addition to the science blogging community, Anna of Anna's Bones, a blog dedicated to anthropology and evolution. Go check her out...