Marisano James

Brief Bio

Image of UC Davis Population Biology graduate student Marisano James.
Figure 0: Picture of me taken at a beach cleaning event.
I’m a Ph.D. candidate in the Population Biology Graduate Group at UCD. Before joining the Eisen Lab I attended undergrad at Franklin and Marshall College, then worked as a software developer in the computer industry for awhile, before graduating from Jacobs University, Bremen, in Bremen, Germany, where I studied Computational Biology and Bioinformatics. I joined the Eisen Lab in 2008, whereupon I expected to study microbial phylogeny or virus evolution but I was lured away to the macro side by a class on the evolution of senses. [So I’d say the Eisen Lab moniker should be something more like, “Mainly microbes, all the time.”]
Marisano beach cleaning closeup
Figure 0: Picture of me taken at a beach cleaning event.


I study the visual system of an enigmatic order of insects called Strepsiptera, which consists wholly of tiny (1–6 mm) parasites of other insects. Unlike the compound eyes of all other extant arthropods, those of adult male Strepsiptera consist of a series of simple eyes that together form the animal’s compound eye. Being simple eyes, each has its own extended retina—of about 60 to 100 photoreceptors, depending on the size of the species—upon which a tiny image is formed. Due to lens dynamics, these images are inverted, and must also be merged to form a useful continuous whole—not unlike what is done to unite the separate pictures of a panoramic shot in a smartphone. But neither of those actions are taken in the case of a typical compound eye, because therein each facet resolves no more than a single point.

Fly eye facet sizesStrepsiptera eye facet sizes
Figure 1: Comparison of the externally typical compound eye of a Drosophila fly with that of a Halictophagus Strep­sip­tera. A) Small abutting facets constitute the compound eyes of this drosopholid, each of which resolves a single pixel. B) The ‘facets’ of this Strepsiptera are much larger because each one projects onto an extended retina, thereby producing multi-pixel images. They are also clearly separated. Because of such differences, the facets of an adult male strepsip­te­ran’s eyes are often referred to as eyelets. Note that the ventral eyelets are much larger than the dorsal ones. This may represent a so-called acute zone of superior vision. (A) was taken from [1]. (B) from [2].

All this peculiarity and ‘extra’ visual work invites one to ask why. What does an adult male Strepsiptera get out of his eyes? (BTW—adult females are blind, wingless, legless, and lack antennae1; but then, adult males starve to death in a few hours…) How well can they see? How did their eyes evolve and why has this eye morphology been retained? To address these questions I’ve been investigating Xenos peckii, a diurnal species, and Elenchus koebelei, a crepuscular species. Among many fascinating attributes, ostensibly Strepsiptera are the only order of insects in which the same eye design is used exclusively in all three major light regimes: broad daylight, dawn and dusk, and late night—so I have designs to work with a nocturnal species too. Stay tuned!

Large image of Elenchus koebeli Strepsiptera

Figure 2: Enlarged image of a dead adult male Elenchus koebelei. Taken for me by ©David Liittschwager, 2013.
Mouse-over the menu buttons above, or pause over parts of the insect’s body.

1. ^This is true of all but a single ancient lineage in which strepsipteran females retain eyes and legs. In that one clade, adult females can leave the body of their host, but they are still very lacking in mobility. This general inability to oviposit freely has led all strepsipteran females to give birth to live young that seek out their own hosts!

Other Info

I am co-advised by Dr. Elke Buschbeck of the University of Cincinnati.


[1] ^Pohl H, Beutel RG. The phylogeny of Strepsiptera (Hexapoda). Cladistics [Internet]. Blackwell Science Ltd; 2005;21:328–374. Available from:
[2] ^Madden V. The head of a fruit fly (Drosophila) — as prepared by Madden [Internet]. Courtright P, editor. University of North Carolina at Chapel Hill; 2009. Available from:

preload abdomen image
preload hilited image of antennae
preload hilited eye image
preload hilited haltere image
preload hilited image of legs
preload hilited mesothorax image
preload hilited metathorax image
preload hilited mouth image
preload hilited prothorax image
preload hilited image of wings

4 Responses to Marisano James

  1. John B. says:

    “adult males starve to death in a few hours…”
    I’m making the assumption that they do not eat. If so, why do they have a mouth? Do they also have a digestive tract? Anus? Maybe these are remnants of a larval stage?


  2. mjajames says:

    Hi John B.: Excellent questions! To be more precise, adult male Strepsiptera either starve to death, or dehydrate, it’s not clear which. In either case, however, they do not feed as adults. This is not uncommon in insects – particularly among males – and also occurs in mayflies, in some species of moths, etc. Adult male Strepsiptera have an incomplete digestive tract, but they do have mouths, in part because they use their specialized mandibles or mouthfield sclerite to remove the cap (cephalotheca) from their pupal case just prior to escape. Why they have other, rather poorly developed mouth parts, is a bit more involved. They are not really holdovers from larval stages – Strepsiptera undergo a complete metamorphosis, consisting of most structures being thoroughly broken down and reconstructed. Instead, it appears to be because there hasn’t been sufficient evolutionary pressure to remove them. That is, the structures aren’t known to be serving any particularly useful purpose, but then, they aren’t causing much harm either. It would probably be more problematic to remove them altogether without causing unwanted changes in other adjacent or related body parts than to leave them to slowly wither away. (“Wither,” because when mutations that degrade them but aren’t otherwise harmful do arise, they’re free to accumulate because the structures are not being used; but “slowly” because those mutations don’t provide much advantage – that is, many specimens that don’t have them are still able to survive and reproduce in very similar quantities.) So I’d say, those mouth parts aren’t leftover larval parts, but instead are evolutionary holdovers.


    • George P. Hansen says:

      Hi Marisano, You reached out to me several years ago about vision in Phacopids, and my website on the Lochkovian (Devonian) trilobites of south central Oklahoma. I remember this now because I ran across some notes I kept, and want to know how you are doing. Also, my son has applied to the graduate school there, and is already living in Davis, auditing some classes, and hoping to be accepted. Have you found any potential links between Phacopid compound eyes and the evolution of these in the Strepsiptera? By that I mean, have you found any trends in the development of these eyes in the parasitic flies that might reasonably apply back to the trilobites by analogy?
      Best of luck to you!
      George Hansen

      Liked by 1 person

      • mjajames says:

        Hello Dr. Hansen: Oh yes, “The Trilobites of Black Cat Mountain.” It has been awhile. Very nice to hear from you! Your son is here in Davis? Excellent. Which department has he applied to? I am doing well, thank you. I should update this page soon… I have recently had a publication in JEB:, so (at least) two photoreceptor classes for (diurnal) Strepsiptera. This condition they share with several beetles, their sister clade. In response to your question: Yes, I have found potential links, with interesting differences. (I wonder what you think of Schoenemann and Clarkson, 2013.) Also, I made it out to Norman, in the summer of 2014. I was seeking out a nocturnal species of Strepsiptera, Triozocera mexicana. It took awhile, but I did learn how to catch males live there. Thank you, and good luck to your son too! Cheers, Marisano


Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s