Well-Nigh Wordless Wednesday: Desert Firetails

I don’t know why exactly, but this has always been one of my favorite damselfly photos:

Desert Firetails

Desert firetails

I took it at the Arizona-Sonora Desert Museum several years ago now, with an older camera with relatively low resolution and depth of field, and it’s not even entirely in focus, but I still like it.  There’s something about the bright red male damselflies peeking out of the front of the photo against the muted greens in the background that just seems right to me.

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Unless otherwise stated, all text, images, and video are copyright © C. L. Goforth

Third Blogoversary!

It’s official! My blog is now exactly three years old. I’m excited! I still have a lot of ideas for things to write about and there are always new entomological discoveries and adventures to feature. I feel like the blog is going strong! So, today please indulge me as I take a moment to review where I’ve been and where I’d like to go with this whole blogging thing.

When I started this blog, I was excited when I got 30 views a day.  Getting 100 views made me ecstatic!  I get more than that now, but it still seems crazy to me that people actually want to read what I write.  I am around so many entomologists that I sometimes forget that many other people do in fact enjoy learning about insects, that we’re not always strange outsiders that no one understands.  I love that so many of you enjoy hearing about the things that get me excited.  It makes the blogging experience fun and I keep at it because it warms my heart to think that so many people are interested in learning about the insects I love.  Yay for the many bug lovers of the world!  You guys rock.  You rock hard.

I think the most exciting part of my blogging experience has been the success of my dragonfly swarm project.  I’ve said it before, but I had absolutely no idea that so many people would participate in this project and I am beyond thrilled at how well it has worked!  I’ve started presenting the results of the project to other scientists and the project has gained the attention of several writers and scientific organizations.  Thank you all, from the depths of my heart, for making my quest for knowledge such a huge success!

One of my goals last year was to have several contests.  I had 3 when I intended to have 4, so I’m feeling pretty good about that.  I haven’t had a contest for a while, and I sadly don’t have time to do one now, but I have a plan for the next one! I’m getting close to 400 posts, so I’ll do another contest when I reach that milestone in about a month.  Don’t know what it will entail just yet, but there’s definitely another contest coming soon.  You’ve all rewarded me with your comments and support, so I want to give something back.

The one goal that I didn’t accomplish at all from last year was moving my blog onto my own website.  I had wanted to do it largely because collecting my dragonfly swarm data was taking so long as I manually moved the data from blog comments or e mailed forms to my database.  Happily, WordPress offered Google Docs support last summer right when I needed it. Problem solved!  Now all the data is magically dumped into a database for me.  That means I’m spending more time doing data analysis and developing new blog posts/educational materials than I spend copying and pasting data.  Woo!  That’s exactly what I needed and it didn’t even involve moving my blog to a new site.  Gotta love it when things just work like that.

My goals for next year are simple.  I’d like to get back to a regular four days a week posting schedule.  It’s not going to happen right away as it’s about all I can do to keep up with my three post per week schedule recently, but I think I can manage four a week after all the craziness dies down.  I also want to review more papers because it gives me an excuse to read them, but it (more importantly) fulfills my goal of spreading the joy of science with non-scientists.  It seems like I get a lot of good feedback when I review papers, so it’s definitely on my to-do list for the coming year because you all seem to like it.  I might also add another semi-regular feature, but I’m going to keep that to myself for now and reveal it if and when it happens.

All in all, I feel like it’s been a good year and I can’t thank you all enough for the support you’ve all shown me.  Hopefully I can keep you entertained for another year – and beyond!

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Unless otherwise stated, all text, images, and video are copyright © C. L. Goforth

Friday 5: Five Reasons There Are Few Marine Insects

Point Reyes

That water out there… Quite inhospitable to insects! (Point Reyes, California)

Last week I mentioned some of the few truly marine insects, the water striders in the genus Halobates. I realized that I haven’t ever talked about marine insects and I think it’s time to rectify that situation! Aquatic insects make up only about 3% of the insects on the planet, but there are only a few hundred species that can be considered at all marine. The vast majority of those are found in estuaries, salt marshes, and other locations where freshwater and marine habitats come together rather than living out in the open ocean. There have been several ideas proposed for why insects have not successfully colonized the ocean, so for Friday 5 this week I give you 5 of those reasons. But first, let me talk about aquatic insects in general.

I know I’ve mentioned it in other posts, but I think it bears repeating: insects evolved on land. There are certainly other arthropods that have lived in marine habitats all along such as the crustaceans, but several million years ago some marine animals (probably crustaceans) crawled onto land and their offspring eventually evolved into insects. Only after they’d established themselves on land did insects begin to colonize water. Insects are thus built for life on land and living in water has presented several challenges that today’s aquatic insects have overcome. But very, very few insects ever colonized the ocean. There’s still a lot of debate about why, but there have been several great ideas put forth, including the following five.

1. Insects can’t survive their whole lives in water

Some insects spend their whole lives in water, including several beetles and true bugs. However, those that do are almost always insects that rely on surface oxygen to breathe and they can’t remain underwater indefinitely. That’s a problem.  It’s hard to be an insect living in the open ocean when you have to stay near the surface. There are lots of things that like to eat tasty little floating protein nuggets, so any insects that tried to colonize the open ocean were likely eaten or faced other problems (lack of places to lay eggs, finding mates in a gigantic ocean, etc) that prevented them from surviving in the ocean. The vast majority of marine insects live in shallow areas along shores, in mangrove swamps, in estuaries, etc, because the habitat is a lot better for them there.

pelican

This pelican would likely be happy to eat an insect hanging out near the surface!

2. The sea is too salty

This idea has been largely rejected at this point, but it’s been around so long I feel I have to mention it. The idea here is that insects can’t survive in salty water because they have problems regulating salt and water in their bodies in salty waters. However, there are several aquatic insects (especially dragonflies and damselflies) that live in brackish habitats that are far saltier than the ocean. Early insects may have had problems adjusting to the salt levels, but considering current insects have figured out ways to deal with it, it’s likely that the salt didn’t form a barrier for colonization of ocean habitats for insects.

hawaii

The salty Pacific Ocean at Lanakai on Oahu, Hawaii

3. The respiratory system will collapse at depths where insects can avoid Predation

As I mentioned above, fish and other predators are a problem for insects living out in the open water. In fact, there are hardly any insects that live in open water even in ponds and lakes, just one family of flies call the phantom midges (Family: Chaoboridae). Being out in the open near the light is dangerous – you might as well have a big, blinking “Eat Me!” sign attached! So, diving deep is important if you want to survive. Unfortunately, diving deep enough to put a marine insect out of reach of fish also means that the pressure is likely high enough to collapse the air-filled respiratory tract and the insect will suffocate. This is one of the issues all aquatic insects face: getting enough oxygen in aquatic habitats with a respiratory system that evolved on land. But, if getting enough air means you’re 99% certain to be eaten by a fish… Well, you might need to find somewhere else to live.

San Carlos

Not many places for an insect to hide if it’s floating near the surface in the ocean at San Carlos, Mexico.

4. Insects are more buoyant in salt water than in fresh

Have you ever noticed that you float more easily in the ocean or salt lakes than in freshwater? Well, the same thing happens to air-filled insects. They float very well in marine environments, which means it’s hard for them to dive into deeper waters and, once again, are very vulnerable to predation if they float up near the surface. Better for them to stay along the shores where there are more things to hold on to at the bottom!

mangrove

Mangroves are nice, hospitable places for marine insects compared to the open ocean

5. crustaceans fill up all the niches

Even if the insects could make it to the bottom where they’re safe from predators, they might still have a hard time finding a place to hide. Crustaceans are close relatives of insects and have lived in the ocean since before insects evolved, so crustaceans may already live in the places the insects might attempt to colonize.  But, the crustaceans have been there longer and can out-compete their land-evolved brethren. This is my favorite of the ideas about why insects haven’t colonized the ocean, but it remains mostly speculation so far.

lobster

A crustacean filling a niche an insect might use?

Though there aren’t very many of them on our planet, marine insects are super cool organisms! If you want to learn more, I recently discovered that the book on marine insects (Marine Insects, edited by the great marine entomologist Lanna Cheng) is available online and as a PDF. I encourage you to check it out! And, the next time you’re by the ocean, looking out over the water, I hope you’ll take a moment to ponder the fact that there is a massive part of our planet where the insects, undeniably one the most successful groups of organisms living on Earth, just can’t survive.  Amazing.  Really amazing.

Point Reyes

The open ocean, as seen on a foggy day from Point Reyes, California

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Unless otherwise stated, all text, images, and video are copyright © C. L. Goforth

Well-Nigh Wordless Wednesday: Saguaros

When I’ve done my summer field work, it typically involves getting up early in the morning and driving out to a pond in the desert to collect giant water bug eggs.  It’s the monsoon season, so the weather is wildly unpredictable, but it does make for some very gorgeous views:

saguaros

Sun coming up on saguaros with monsoon clouds in the background

I’ve lived in Arizona the majority of my life, but I never get tired of looking at saguaros.  They’re just so darned stately!  Really going to miss them when I move on.

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Unless otherwise stated, all text, images, and video are copyright © C. L. Goforth

Insects and Plants Use the Same Strategy for Breathing Underwater

Exposing the air store

A giant water bug, Abedus heberti, breathing using a physical gill

You all know that I have a soft spot in my heart for all things related to aquatic  insect respiration.  I’ve written several blog posts about the topic in the past.  I was thus very excited to come across a new paper a month ago, a commentary on physical gills in aquatic invertebrates and plants by Ole Pedersen and Timothy Colmer.  It was the first time I’d ever considered the possibility that plants might have hit upon the same means of underwater respiration as insects.  Mind blown!  So, I’d like to share the paper with you all too, just in case any of you find it as fascinating as I do.  (One can dream, right?)

Freshwater insects, spiders, and plants all have one thing in common: they are adapted for life on land and depend on respiratory systems that were intended for use in air.  Oxygen is much less abundant in water than in air and moves very slowly through water, so any organism built for living on land that wants to move to an aquatic habitat has to adapt to the available oxygen of their new watery home.  Insects have evolved a variety of means of compensating for the relatively low oxygen levels in water, many of which I highlighted in another blog post.  These include snorkels (such as those on giant water bugs and water scorpions), scuba tank style air stores (also in the giant water bugs, among other true bugs and many aquatic beetles), physical gills (many true bugs and diving bell spiders), plastrons (in a very limited number of aquatic insects), and gills (damselflies, mayflies, hellgrammites, etc).  According to Pedersen and Colmer, nearly all of these animals must return to the surface at some time to refresh their air supply because the respiratory needs of the animal is greater than the ability of the respiratory surface to supply oxygen.

However, gas films such as physical gills and plastrons significantly increase the length of time an organism can remain submerged.  These air films are so important that Pedersen and Colmer suggest that many insects that live in riparian areas or around ponds have body surfaces capable of trapping air films too.  These may prevent drowning if a terrestrial riparian insect becomes submerged, either accidentally or by choice.  Air films are clearly important to a variety of aquatic and riparian insects and spiders.

cattails and algae

Cattails and algae help clean the water

But they’re also important to plants!  The authors discuss how many wetland plants have surfaces that repel water and create gas films around the surface of submerged leaves.  These gas films work the same way they do in insects – absorbing oxygen from the water and improving the respiration of the organism in water.  Plants don’t have the necessary structures to create permanent plastrons, but a plant that is submerged (during flooding, for example) can often survive two weeks or more completely submerged thanks to a little film of air that surrounds it.

The authors did a short study comparing the oxygen uptake by both an insect (a true bug in the genus Aphelocheirus, one of the plastron-bearing insects that only very rarely goes to the surface) and a plant (reed canary grass, Phalaris).  They found that gas films strongly improved the ability of both the insect and the plant to take up oxygen from the water and that the gas films worked in both high and low dissolved oxygen concentrations.  The authors also removed the gas films and discovered that the oxygen uptake strongly decreased.  In the end, they concluded that gas films increase the area through which organisms can absorb oxygen from the water, greatly enhancing their ability to survive underwater and the time they could remain submerged.

Sweetwater

Sweetwater Wetlands

The authors further suggest that gas films might aid in plant photosynthesis.  Plants require carbon dioxide to photosynthesize and normally it enters the plants through pores in the leaves called stomata.  In water, however, stomata are thought to close, so carbon dioxide must travel directly through the leaf’s surface, a long and slow process.  Plants with gas films have an advantage: they can both absorb carbon dioxide more readily through the gas film than without it and they likely keep their stomata open, allowing carbon dioxide to easily flow into the leaves and allow photosynthesis to take place.

shallow treatment

A giant water bug going to the surface to get more oxygen

Pedersen and Colmer concluded with a few comments about water quality and gas film respiration.  They posit that these sorts of systems only work in relatively clean water, that in polluted waters the oxygen levels are too low to support submerged plants and animals with simple gas films.  In dirty water, insects with snorkel or scuba tank like respiratory systems stand a better chance of getting the oxygen they need because they don’t depend on oxygen in the water and go to the surface for oxygen instead.

What I really like about this paper is the connection it draws between the plants and arthropods, how two very different groups of organisms have hit upon the same solution to functioning underwater.  Clearly this system wouldn’t work for all wetland organisms as animals with lungs don’t passively absorb oxygen the way plants and arthropods do, but gas films seem to work well for things that have more passive respiratory systems, regardless of the type of organism. I think that’s pretty darned cool!  Plants and arthropods are wildly different organisms and it’s simply amazing to consider that they’ve developed similar solutions to deal with living in and around water.  Yet one more example of how fantastic the natural world is!

Literature Cited:

Pedersen O, & Colmer TD (2012). Physical gills prevent drowning of many wetland insects, spiders and plants. The Journal of experimental biology, 215 (5), 705-9 PMID: 22323192

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Unless otherwise stated, all text, images, and video are copyright © C. L. Goforth

Friday 5: Papers I Haven’t Had Time to Read

Hello everyone!  You find me in a state of mild panic and I can safely say I’m one big ball of stress.  I have a whole lot going on right now, most of which is good (nay, excellent!) that I’ll share soon, but for now I’m just busy.  From about 7AM until midnight.  Every day.  So, some things I like to do have fallen by the wayside for a bit, including reading the random scientific papers I usually read and sometimes share with you all here.  But it’s Friday, so it’s time for Friday 5!  Today’s is a simple list of papers that I really want to read, largely so I can share some of the amazing, awesome, cool, or otherwise spectacular things insects do with you.  So, consider this a sneak preview of things (most likely) to come!

Halobates

A Halobates water strider specimen. Image by Michael F. Schönitzer, licensed under Creative Commons. Click image for image source.

1. Oceanic water striders love floating plastic junk.

There’s approximately one genus of aquatic insect you find out in the middle of the ocean, the water strider genus Halobates.  They’re super cool little bugs, floating around on the surface of the ocean way out in the middle of nowhere.  And apparently they LIKE all the plastic junk floating around out there!  It’s an interesting case where one species is actually benefiting from pollution, in this case by increasing their chances of finding a place to lay their eggs.  Dying to read this one…

Mo the frog

Not a tadpole, but this little bullfrog started out as a tadpole when I accidentally collected him. I didn’t get any good shots of the tadpole stage at all…

2. Roundup (the herbicide) in water causes responses in tadpoles similar to those observed when they are in the presence of predators such as dragonflies.

Amphibians are rather flexible animals, changing their body forms in response to a variety of environmental stressors.  That’s unfortunate as many chemicals end up in our water by one way or another and they can do some pretty awful things to thin-skinned frogs and tadpoles.  In an interesting recent study, researchers discovered that the widely used herbicide Roundup caused tadpoles to develop longer tails and different behaviors and that those tails/behaviors are nearly identical to those seen in tadpoles exposed to dragonfly predators.  In other words, a chemical is causing the same sort of responses in the tadpoles that a predator normally would!  Pretty interesting, and a little sad, so I really want to read the rest of the paper.

Rincon Creek

Believe it or not, this is actually a stream. That pipe you see in the lower left – that’s a stream gauge!

3. River drying decreases the diversity of terrestrial insects and other arthropods in the riparian area.

I’ll be honest: the results of this study seem rather obvious, but I’m still excited to read the paper.  The authors discovered that when the water in a section of a desert river disappears, so do a lot of the terrestrial insects and other arthropods in the surrounding area.  Apparently terrestrial insects are affected by river drying just like their aquatic relatives.  Perhaps not to the same extent, but what’s bad for the aquatics seems bad for a lot of other things in the area.

Backswimmer

A backswimmer. The shiny parts are the air films.

4. Physical gills protect insects, spiders, and plants from drowning.

I’ve talked about physical gills in insects, the thin films of air that many aquatic insects carry that act as gills while they’re submerged, several times in the past.  A recent paper suggests that both plants and arthropods have hit upon the same solution to the problem of drowning: physical gills.  It’s pretty darned cool when two completely different organisms, in this case organisms from two different biological kingdoms even, end up doing the same sorts of things.  Super interesting!  At least it’s interesting  if you’re me.  You’re all just like me, right?  Anyone?  :)

insect spiracle

A spiracle on a caterpillar. The blue arrow points to the opening.

5. Discontinuous gas exchange in insects might have developed to lessen oxygen free radical production.

Another respiration paper!  This one focuses on the discontinuous gas exchange cycle (DGC), a form of respiration in some insects that involves opening the spiracles (the holes through which air enters the respiratory tract) only periodically and effectively “holding their breath” the rest of the time.  There’s been several ideas put forth about what how this complex and interesting system benefits the insects that use it, but this article reports evidence that discontinuous gas exchange helps reduce the production of harmful oxygen free radicals by using free radical production as a trigger to open the spiracles and release carbon dioxide.  This might not sound exciting to any of you, but I can’t wait to read this paper!

Someday soon I’ll have time to start reading some of these papers and reporting about them here.  But that will have to wait.  For now, back to work!

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Unless otherwise stated, all text, images, and video are copyright © C. L. Goforth

Well-Nigh Wordless Wednesday: Bee on Catkin

I know the world has a ton of bee-on-flower photos, but I really love the flowers of mesquite trees, and bees on the flowers make them extra nice:

Honey Bee on Mesquite Catkin

Honey bee on mesquite catkin

Ah, spring/summer in the desert!  What a glorious experience!  (Well, right up until it gets above 105 degrees outside.  Then it can become decidedly less glorious if you’re working out in the sun.)

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Unless otherwise stated, all text, images, and video are copyright © C. L. Goforth