Diario de littleant

Recently, when I finished a series of behavioral interactions with the Comanche harvester ant I study, this beautiful, small (about 5 mm), male jumping spider landed on my hand and distracted me from my work. I managed to shake him off my hand onto a plastic cup and got a few photos.

Jumping spiders are in the Family Salticidae, a name which derives from the Latin saltare, to jump or bounce, which suits these spiders perfectly. Unlike most spiders, the salticids (another name for jumping spiders) do not use webs to catch their prey; they pounce on them instead. In order to do this, also unlike most spiders, they have excellent, color vision. They have four color pigments (not three as we have). Their two large eyes (the AME or anterior median eyes) are the ones most important for their vision. These eyes look a bit like headlights.

One of the difficulties for spiders is that because they have an exoskeleton, the lens is hard and cannot be reshaped to focus their vision — the lens is part of the exoskeleton. However, the jumping spiders have overcome this problem by having moveable retinae. They have muscles which move the retinae up and down and all around — so they can focus and look around without moving their heads or rather their carapace. Quite amazing.

These spiders also use their vision in courtship. The males perform dances that show off their coloration to court the females. The females look for the right moves that show off the right color pattern — one way to identify species. To make this a bit difficult, the particular jumping spider which landed on me, Maevia inclemens, has males with two entirely different color patterns: a grey form and a dark form. Each color form has its own version of the courtship dance. The one I saw is the grey form. The males of the dark form are all black without other colors or patterns. The females look like the grey form in coloration. Now if you were a female salticid which would you choose?

I observed a large female golden silk orb weaver spider (Nephila clavipes) on her orb web in the shade at Emerald Isle, North Carolina (August 7 and 8, 2013). Initially there was one small male several centimeters away from her. Several hours later, I came back to the web and there was a second small male much farther away in the web. A bit later, there was only one male in the web (where the first one was). I had thought the male was there to mate but never saw the mating. I considered that this male might be guarding though I am not aware of such behavior for this spider. The next morning I could not find the female but the male was in the center of the orb about where the female had been.

There were also several funnel web spiders (Agelenidae) with webs touching and near the Nephila clavipes web.

In my prairie sites at the Fort Worth Nature Center in Fort Worth, Texas, where I study the Comanche harvester ant, I have found two species of Trachymyrmex ants: T. septentrionalis and T. turrifex. I have 14 prairie sites and of these 8 have both species, 5 have only T. turrifex and one has only T. septentrionalis. Finding both species is quite exciting for two reasons: first, these are funky looking ants with all kinds of spiny projections on their bodies. So, they were one of the first ant genera I learned to identify correctly. And they are very cute. But the more exciting thing has been the discovery of the nests of T. turrifex, which are turrets. They have a bit of a crater area in the middle of which is this turret, about 2 and ½ inches long. I was quite astonished when I happened upon some of these structures and more so when I saw ants coming in and out of them. I got some photos and some video as well (http://youtu.be/1x6Z2kXe-5Y).

The nest of T. septentrionalis is very different. The entrance is a few centimeters from a characteristic crescent shaped pile of soil which they make as they excavate their nest. Earlier this summer, I found some Solenopsis xyloni easily coming and going in and out of a T. septentrionalis nest. The S. xyloni, a native fire ant species, and T. septentrionalis met each other at the entrance to the Trachymyrmex nest without out any sign of aggression and the S. xyloni preceded to enter the nest. Trachymyrmex expert Dr. Jon Seal (University of Texas-Tyler) has observed the same but does not know what is going on.

Trachymyrmex ants are related to the leaf cutter ants in the genera Atta and Acromyrmex. Though technically, not leaf cutter ants, Trachymyrmex ants may collect leaves to grow fungus like the true leaf cutter ants. But my understanding from Jon Seal is that Trachymyrmex ants are not obligate fungus eaters. They forage on other foods as well.

This Field Trip was part of the 2013 America's Grasslands Conference, held recently in Manhattan, Kansas. You can read my whole account with photos in my open notebook called Ant Ecology and Other Adventures, as well as an account of the meeting, at http://tinyurl.com/lsesc7q

I give the link rather than writing a different account because on my open notebook I include panoramic photos of the prairie and of local buildings that would not be appropriate to upload here. Many of the flower and insect photos are on the iNaturalist site.

(I wrote this to try to share the excitement of discovering new ants and identifying them. I thought I would share this as a journal post here as well. Unfortunately the mini trap draw ants, Strumigenys are so tiny that I am unable to get a photo but you can see this and some other species at Alex Wild's site: http://www.alexanderwild.com/)

When I was a kid, Christmas morning was a great time. My brothers and I would rise early and dive into our Christmas stockings crammed full with toys and candies. There were things we always expected like the maple sugar Santa Claus, a tangerine, and a toothbrush but there were also surprises – toys and puzzles we hadn’t imagined. We spent most of the day playing with these toys, sharing them, and making up new games.

Today, I have a similar experience with ants—Yes, those six-legged creatures that you don’t want at your picnic. For the past few years I have been catching ants with pitfall traps in the Fort Worth Nature Center of Fort Worth, Texas. Ants wander into the traps. Then, I collect them.

Setting out the traps is hard work but because ants come in all kinds of shapes and sizes, waiting to see the ants is exciting. I sometimes dream about the ants: What might I find? Ones I expect or something new? Looking over the catch is like dumping out my Christmas stocking: I have some idea what might be there but there could be surprises.
Having collected ants in the Fort Worth Nature Center over three years now, I am used to particular ants – like the maple sugar Santa Claus, they have become old friends. While I am glad to see them, they are not quite so exciting as the first time I saw them. This summer, the last ant of the last pitfall trap was a new ant – that is, new to me. This ant was a queen ant, so she could have started a new colony. She was not only a new species, she was a new genus and a new tribe.

This ant was a trap-jaw ant called Strumigenys louisinae. This particular ant is quite small and so is difficult to find. These ants eat tiny insects called springtails (Collembola) which have springs in their abdomens that allow them to quickly escape from predators. The ants have jaws that are long and narrow with special teeth at the end. Their heart-shaped heads contain strong muscles necessary to operate the jaws. Holding the jaws open, the ant makes a trap which closes with lightning speed: snap! and the springtail is lunch.

I have found lots of springtails in the pitfall traps. Now I know what is eating them: this trap-jaw ant. I am wondering more about this trap-jaw ant but also what other ants are in the Fort Worth Nature Center and what interesting ways of life do they have. Lucky for me I still have more collections to make, so, I continue to dream of the interesting ants I have yet to discover, not only in Texas but in other places too. What ants are in your area and what do they do?

Acknowledgements: I am able to discover such cool ants thanks to the staff of the Fort Worth Nature Center and Wildlife Refuge and the Parks and Community Service Department of the city of Fort Worth, Texas.