Friday 5: Non-insect Arthropods of the Sonoran Desert


Warning: The creepy factor of today’s post is going to be quite high.  Just want to give you a head’s up before you dive in.

The Sonoran Desert is an amazing place!  It’s greener than people expect, we’ve got awesome giant cacti like the saguaro, and the diversity of life is astounding.  Many entomologists think southern Arizona and northern Mexico are among the best places to study and/or collect insects in the world, and people come from all over specifically to check out our insects.  (People also come from all over to stay warm during the winter, but that’s a story for another time!)  Of course,  Arizona is also known for several other animals, some of which can actually be dangerous if you’re not careful, like the rattlesnake in the photo, or just plain scary for a lot of people.

Today I’m going to introduce you to several non-insect arthropods that live in my area.  These are things a lot of people are very scared of, but these are some amazing animals that deserve their own post!  Let’s begin with an arthropod I’ve already featured in a post about my field site and the undead animal I fished out of the pond there:

Giant Red-Headed Centipede, Scolopendra heros

Scolopendra heros
Scolopendra heros

I freely admit that these things scare the daylights out of me.  They’re fast, they’re enormous (up to 8 inches long!), and there’s something about those legs that I find incredibly disturbing.  (It’s not the number – millipedes don’t bother me at all – but the way they move…)  Still, you have to admire this animal.  They have stunning coloration that even I can appreciate.  They’re fierce predators, using their modified forelegs (called forcipules) to inject venom into their prey and paralyze them before they chew them up.  Watching one of these things eat is both horrifying and awe-inspiring!  Plus, you have to respect any arthropod that gets this big.  I’m always amazed when I see them running around the desert at night – and very, very thankful that my tent has a good zipper on it!

Desert Blond Tarantula, Aphonopelma chalcodes

Aphonopelma chalcodes tarantula

Aphonopelma chalcodes

I find that people who are scared of spiders are often able to appreciate tarantulas.  It probably helps that they move slowly and are generally harmless to people, plus they look fuzzy enough to be stuffed animals.  I think tarantulas are great!  Desert blond tarantulas tend to stay near their underground burrows to hunt, though males can venture further when searching for females, especially after monsoon storms.  I think the coolest thing about these spiders is how they defend themselves from predators.  When disturbed, they will brush their hind legs over the top of their abdomens, which releases a cloud of hairs.  These hairs have hooked barbs on them, which means they embed themselves into the eyes, mouths, and noses of things that think a tarantula might make a tasty treat.  The embedded hairs are known to be terribly irritating.   Although I have not experienced this defense first hand, I have a feeling it’s rather like getting the tiny spines from prickly pears stuck in your fingers, i.e. really, really annoying!

Sun Spider or Solifugid, Eremobates sp.

Eremobates solifugid

Slightly blurry photo of an Eremobates solifugid

Solifugids are rather creepy looking arachnids, but you just have to love them!  Also known as sun spiders or camel spiders, solifugids can get quite large in certain parts of the world.  In the Sonoran Desert, they can approach 2 inches in length, but I rarely see any that big.  Solifugids are predators and they can chase down their prey with those long, fast legs.  The blurry photo is the result of this solifugid stalking a cricket and refusing to sit still!  That pointy black bit up at the front is the business end of the solifugid, powerful mouthparts they use to rip apart their prey before they liquefy their food and eat the resulting soupy mess.  These animals are often erroneously said to be dangerous to humans, but they really can’t do much to you except bite.  Honestly though, who’s going to pick up an animal that looks like this and give it a chance to bite them?  I love to watch them, but I leave these guys alone.

Vinegaroon, Mastigoproctus giganteus

Mastigoproctus giganteus

Mastigoproctus giganteus

Vinegaroons, also known as whip scorpions, are gnarly looking beasts, but their scary looks belie their laid back demeanor!  They’re not venomous, they generally don’t bite people, and they can become quite docile.  Even I’m willing to handle these, and I’m a total wimp when it comes to picking up arachnids!  Vinegaroons are fascinating animals.  Those big, thick projections off the front end are mouthparts called pedipalps, powerful pincers used to capture prey (arthropods and some small vertebrates).  Notice that the vinegaroon in the photo is standing on only 6 legs instead of 8.  That’s because the front legs have been modified into sensory structures similar to insect antennae!  The tail in the back allows the vinegaroon to protect itself from predators, though it isn’t a stinger.   Instead, vinegaroons have glands near the end of the abdomen that store a mixture of acids, including acetic acid (the acid that gives vinegar its distinctive smell and taste – hence vinegaroon!).  When disturbed, the vinegaroon points its tail at the predator and ejects some acid from the glands.  The acid travels up the tail and sprays the predator in the face.  As you might imagine, getting a face full of acid spray will slow most animals down, giving the vinegaroon time to run away.  Now tell me that’s not the coolest thing you’ve ever heard!

Arizona Stripetail Scorpion, Vaejovis spinigerus

Vaejovis spinigerus stripetail  scorpion
Vaejovis spinigerus

Although many (maybe most) Arizonans are scared of all of the animals included in this post whether they’re harmful or not, I think the scorpion is probably the most feared of them all.  We’ve got three common species of scorpions where I live, and all of them have painful stings.  The bark scorpion can actually be life threatening under the right conditions, so it’s good to give these animals a lot of respect.  Still, what a magnificent animal!  Just looking at a scorpion should help you appreciate how very long these beasts have roamed the earth.  There’s something incredibly primitive about them, yet look at the scorpion in the photo.  Isn’t it stunning?  With the morning light shining through its tail it’s almost pretty!  My students found this little one half-frozen under a rock on a very cold morning after a frigid night of camping.  We were enthralled by it and I’m glad I captured it in a photo so I will always remember how glorious this one was.

Even though I am scared to death of the centipedes and you really do have to look out for the scorpions to avoid getting stung, I love living in a place that has so many interesting animals!  The fact that I’ve seen all of these live in the desert on several occasions makes me really happy and I think it’s a real treat to come across a vinegaroon or a solifugid while collecting insects or simply enjoying being outside.  Isn’t nature spectacular?!


Unless otherwise stated, all text, images, and video are copyright © 2011

Studying Invertebrate Behavior on YouTube

image from class

An experimental setup in my recent insect behavior class. The students were studying how water temperature impacted respiratory rate in the giant water bug Abedus herberti.

As a lab instructor for an insect behavior class, I use a lot of live insects in my class.  The students enjoy working with them and are generally happy they don’t have to watch videos the entire semester.  Trust me – watching hours and hours and hours of insect behavior video can get really dull really fast.  Live insects are definitely the way to go for a class where most of the students do not have the level of patience that I do.

Unfortunately, the class is held in the spring, so there’s just not many insects out until the end of the semester.  This means that my students work mostly with my favorite insects, the aquatic insects, which is good.  However, it also means that they have a fairly limited variety of things to work with, i.e. things that overwinter as nymphs or adults.  I am able to collect a decent variety of aquatic insects during the winter in Arizona.  Still, there is one lab that would be SO much better if we had a bigger variety of insects to work with: the predator lab.

I developed the predator lab four years ago when my students at the time were constantly begging to put two hungry predators together and watch what happened in the ensuing death match.  (Did I mention that my students are college seniors and grad students and NOT 5 year olds?)  In the interest of turning this morbid curiosity into a teachable experience, the predator lab was born.  In it, I have the students feed several different predators and compare and contrast their feeding behaviors.  They have to watch how the insects capture and devour their prey and describe how they do it in detail.  They also have to tell me whether the insect is a sit and wait predator (they stay in one place and wait for food to swim, walk, or fly by), an active predator (they purposefully hunt down and attack their prey), or something else.  This way, the students get to watch several predators capture prey and eat it, fulfilling their need to promote death and destruction, but they are doing it in some meaningful context.

The predator lab is my favorite.  It requires a lot of work on my part to collect the insects and prepare the containers and prey items for the bugs, but the students get so into the activity that I can’t help but love it.  Even my quietest class, the class I just finished last month, got into it and actually made some noise in class for once!  And things get even better toward the end of the class period when they have finished their work for the day and I let them feed the things that don’t survive well in the lab to my water bugs or to each other.  This is the treat at the end of the semester, their reward for making it through what I consider a very work-intensive course: the death match they’ve been eagerly hoping to set up all semester.  This year there was also a water bug eating a fish to watch (click on the link to see the video!).  That really got the students excited.

Unfortunately, this year was a terrible year for aquatic insects in my part of Arizona.  We got a ton of rain during the winter and there was extensive flooding in the mountain streams that washed out the insects.  The populations didn’t rebound very quickly and there was hardly anything in the streams even several months after the floods.  I was hard pressed to get enough insects for my class this year and we ended up with a measly three types of insects for the predator lab this year: some small predaceous diving beetles, some dragonfly nymphs, and some of the smaller giant water bugs.  It doesn’t take very long to feed a hungry insect, so I brainstormed ideas for activities to fill up half of the class period.  I eventually settled on something I knew the students would love: showing some of the spectacular videos of predatory insects on YouTube.

YouTube is a rather amazing repository of insect behavior data.  A lot of the video is collected by amateurs and many of them know very little about the insects they’ve filmed.  That doesn’t matter – there is some great stuff on there if you know where to look!  For my class, I chose some of the most showy videos I could find.  My students had spent the semester watching live insects.  A video has to be amazing to hold my students’ interest at the end of the semester and the 8 videos I settled on fit the bill well.  And because they are too good not to share, I am posting them here so that everyone who reads my blog can see them too!

Army ants:

Damselfly eating another damselfly – check out the mouthparts moving!:

Preying mantis vs. mouse – and the mantid wins!:

Centipede vs. mouse – and the centipede wins!:

Spider captures and kills a bat:

Antlions (are awesome!):

Orchid mantid captures fly:

I can safely say that this was an excellent way to kill some time in class.  The students loved the videos (there were several collective cries of “Whoa!” during lab that day!) and actually learned something in the process.  A few of them even referenced the videos in their lab write-ups!  It was so successful that I think I will do this again the next time I have an opportunity to teach a behavior class, even if I do have a lot of animals to use in class.  It was great for the students to get to see some things we couldn’t possibly duplicate in class and let them see some more insects in action after their regular lab activities.  It was a great way to finish the last lab of the semester.


Unless otherwise stated, all text, images, and video are copyright © 2010

Field Stories: The Stuff of Nightmares

I believe that almost all entomologists have at least one arthropod or other animal that they really don’t like and find disturbing on some primal level.  Several of my best entomologist friends, including one who thinks ticks are the best animals ever, think roaches are the most vile beasts on Earth.  A herpetologist friend of mine gleefully handles rattlesnakes but completely loses her nerve when faced with a scorpion.  I know several biologists who are terrified of grasshoppers and other jumping insects, and even a few who really hate moths.  I personally don’t have any problem with roaches, or most other insects for that matter.  But there is one arthropod that I find incredibly disturbing, and that animal is the centipede.

Something about a centipede screams “This is an unnatural spawn of the devil!” to me.  I really, really hate them.  REALLY hate them.  They terrify me beyond almost any other animal.  I am not a scream at the top of my lungs kind of gal, so there’s rarely girlie shrieking involved when I come across one, but serious chills do run down my spine and I always involuntarily shudder.  Just thinking about them makes me anxious!

Because I dislike them so much, it figures that I live in a place that has some of the biggest centipedes in the world.  Meet Scolopendra heros:

Scolopendra heros

Scolopendra heros

This beast is also known as the giant redheaded centipede, which is yet another example of biologists giving organisms highly descriptive (aka, uncreative) names.  As you can see, this is an arthropod with many legs, but only one pair per segment, which makes it a centipede.  This thing is about 6-8 inches long, so it’s giant.  And it has a red head, hence redheaded.  I feel like I should think this centipede is beautiful and I certainly don’t begrudge anyone who does.  The colors really are fantastic!  And the ones in Arizona have even more red on them than the individual pictured here (there are several different color variations in this species).  Still, these are things of nightmares for me.  I think the problems I have with these animals are based on the fact that they are venomous (they’re predators and use their venom to subdue their prey) and they are fast.  Very fast.

Now that you know a bit more about these centipedes, allow me to tell you a story about an encounter I had with one.  If you’ve been keeping up with my blog, you’ve probably read about my field site already.  One day a few years ago, my advisor and I were made our daily summer trip to the pond to collect water bug eggs.  I strapped my waders on and climbed out into the pond as usual.  However, the water was remarkably clear that day and I could actually see all the way down to the bottom for the first time ever.  What I saw there, however, was horrifying: a Scolopendra heros sitting on the bottom of the pond, right by one of the sticks I needed to check for eggs.  The conversation with my advisor went something like this:

Me: (Yells to advisor) Whoa!  There’s a Scolopendra on the bottom of the pond here!
Advisor: That’s great!  Pick it up and bring it over here!
Me: Oh hell no!  I’m not picking it up!
Advisor: Chris, don’t be a wimp.  Pick it up!
Me: No!  I don’t think it’s dead.  (Pokes it with a stick to see if it moves.)
Advisor: It’s not moving?
Me: No.  (Poke, poke)
Advisor: If it’s not moving and it’s on the bottom of the pond, it’s probably dead.  Just pick it up!
Me: (A bit of hysteria creeps into my voice) No!!!  I’m not picking it up, even if it IS dead!  I hate these things!  But I really don’t think it’s dead…  (Poke, poke)
Advisor: (Shakes head sadly, conveying his utter disappointment at my squeamishness.  I have clearly failed his test of entomological robustness.)

In a bout of sheer wussiness, I eventually consented to pick the thing up with a stick.  I draped it’s limp body over the very far end of the three or four foot long stick and held it as far away from my body as I could, just in case it suddenly came back to life.  I was terrified I would get stuck in the mud and fall over and I could just see the demon spawn I was carrying flying through the air and landing on my head.  But, I made it to the shore unscathed and made my advisor hold a bag open for me (which he did only after making fun of me again) so I didn’t have to get the centipede close to my unprotected hands.  I was in the process of making an insect collection for a K-12 outdoor education center and knew it would make a good addition to my collection.  My advisor handed the bag to me and I quickly tied it shut.  I carried it back to the car holding it out from my body and grabbing only the tiniest part of the corner furthest from the centipede so I could keep it as far away from me as I could.  I kept looking at it and expecting it to wake up.  I was absolutely convinced that it was still alive.  I happily tossed it in the plastic box with my waders and slammed the lid on, thankful the centipede would be riding home in the back of the truck while I was safely in the cab.

When I got home, I carefully carried my wader box inside and pulled the lid off slowly, carefully peering in and expecting to see a lifeless centipede inside.  What I saw instead was exactly what I had feared!  The centipede was indeed still alive and was now running frantically around the bag.  I imagined that it was now a very angry venomous creature trapped in a very thin film of plastic that I was sure it could find a way out of.  I had to do something and fast!  My worst nightmare was about to come true: a livid centipede bearing down upon me across my kitchen counter while I was paralyzed in fear and helpless to prevent its leaping onto my face.  (Okay, so I have a vivid imagination!)  I grabbed the corner of the bag, the one now holding a squirming, probably unhappy centipede, and tossed it into the freezer, slamming the door shut before slumping against the fridge door and sighing in utter relief.  I conquered the menace that was the evil centipede!  And I was preserving it for a good cause, thereby killing two birds with one stone.

Or I would have been killing two birds with one stone except I’ve never taken it back out of my freezer.  I’m too creeped out by it to retrieve it from it’s frigid habitat.  Knowing it’s in there still is bad enough (and I carefully avoid it when rooting around in there for food), but actually getting it out, facing it’s horribleness once again?  Well, that’s just not going to happen willingly.  The real question is, when I eventually move, will I have the courage to take the centipede out and finally add it to a collection, or will someone from the rental company be in for a very nasty surprise?  I can’t say for sure until that day comes…


Text copyright © 2010