eyes

A(i)nt and gast(e)ropost

While at the Los Tuxtlas field station I had the opportunity to be attacked by numerous arthropods, including trombiculid mites (chiggers), numerous species of ants, and an urticating caterpillar. Don’t laugh about the caterpillar!  They can kill you. But the one that got me only left a caterpillar-shaped welt on my shoulder. I’ll describe two ant attacks of note. One involved an invasion of sleeping quarters by male and female ants after a hot day and heavy rainstorm induced a flight of reproductives. The bedroom walls and ceiling were covered in winged ants, which proceeded to fall down on the bed at night. One added both injury and insult by biting my bottom.

winged ant queen like the one that bit me in bed Los Tuxtlas 18 July 2014 sml

One of many reproductive female ants that swarmed the bedroom in Los Tuxtlas. Unfortunately, I don’t know the genus.

The next morning I took some photos of the remaining reproductives, which revealed that the males have grotesquely enlarged and protuberant ocelli.  A cursory Googling revealed that ocelli tend to be larger in reproductives of night-flying ant species, but I couldn’t find a good explanation for the sexual difference. This paper suggests that males of Myrmecia (a genus different from the that of the ants that fell on me) may have to engage in more intense visual tracking to find the females for mating.

ocelli of female vs male reproductive ants Los Tuxtlas 18 July 2014 sml

Heads of female (left) and male (right) reproductive ants showing the difference between the sexes in relative size and sphericality of the three ocelli.

The second ant attack occurred when I was peaceably watching a lecture on salticid taxonomy in the lab. Suddenly I felt a burning pain on my throat. Remnants of the crushed body of the perpetrator revealed that it was a Pseudomyrmex, probably P. salvini.  This ant was many times larger than the other species of Pseudomyrmex that had attacked my hand near Chamela, and it produced a goiter-like swelling commensurate with its size. I don’t know what induced it to stab me in the neck – sheer viciousness, perhaps. But on the bright side, the nasty nature of the Pseudomyrmex is probably why a particularly striking species of jumping spider mimics it. The a(i)nt pictured below with its model is a species of Synemosyna. They were common on the station walls and foliage.

Pseudomyrmex most likely salvini and Synemosyna mimic Los Tuxtlas 14 July 2014

Pseudomyrmex ant on left and a mimicking Synemosyna salticid on the right.

 So there is the gasteropost – on to the gastropost.  In Morelia we had much enjoyable food and drink, including a surprisingly good Mexican IPA, but there was also some awful stuff. One meal resulted in a three day trial of having my Edmontonian gut flora violently replaced with a Morelian community. After that had settled down, I decided I was digestively robust enough to sample a mysterious drink called a ‘Michelada’, which was advertised everywhere, but I had no idea what it might be. When the beverage arrived, this is what it turned out to be:

Michelada trimmed

Creating the Michelada – beer plus Clamato juice. Urgh. (photo by Wayne Maddison)

I managed to drink about a fifth of the concoction before the guts said ‘no’! Tastebuds concurred. But as odd as this beer+Clamato sounds, there is an equivalent in Alberta: the Red Eye. Why someone decided to replace the vodka in a Caesar with beer is unclear to me.

A more pleasant food experience took place in Mexico City after I had given my talk at UNAM. My host, Dr. Tila Pérez, took me and some other arachnologists to a traditional restaurant for lunch. There in addition to delicious moles (poblano, negro, verde and rojo), we sampled some unusual appetizers. My favourite was escamoles – fried ant juveniles (maybe a mixture of larvae and pupae) served with guacamole and eaten with tortillas. They tasted like buttery fried things, and I enjoyed them maliciously.

escamoles - fried ant pupae raised on agave roots Mexico City 28 July 2014

Fried baby ants – delicious revenge! (photo by Grislda Montiel)

Advertisements

Size and eyes

Yesterday we collected 17 live opilioacarids from under stones near the Chamela station greenhouses.  Their light purple colour makes them stand out relatively well against the reddish soil encrusted on the bottoms of the rocks. But they are pretty small and getting one off a rock can involve quite a chase with a paintbrush as they dash in and out of crevices. In case you want to know how big they are, here is a photo of one in a vial with my left index fingerprint for scale. The closeup shows how the camera’s flash is reflected by a tapetum in the eye of the mite – a feature unique to opilioacarids among both parasitiform and acariform mites. In spiders, presence of a tapetum seems be an adaptation for night vision (but not all nocturnal spiders with good vision have a tapetum according to this  Australian Museum post). Does the tapetum in opilioacarids mean that they come out from under rocks at night? Or that they use these fancy eyes to better navigate their dark sublithic world?

opilioacarid with fingers for scale and tapetum compilation16 Feb 2014