30 June 2007

What, me drunk?

drunken goat cheese + raki

I found this cheese at Whole Foods Market last weekend. I had never had or heard of drunken goat cheese before. I like it. It's soft, feels creamy in one's mouth and has a nice aroma, although I don't know how to describe it. My wife thought it was a cross between feta and kasseri. It went well with a glass of rakı, the national alcoholic beverage of Turkey, known as ouzo to the Greeks.

But to set the record straight, it was the goat who was drunk. I was only tipsy.

29 June 2007

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28 June 2007

Dawkins and the wishy-washy god

Snippets from Richard Dawkins' recent interview with the Guardian's Alok Jha:

When you talk to people like bishops...they look to me as though they don't really believe in a supernatural being... The sort of god that they believe in seems to be so wishy-washy, so sort of undefinable, so hard to get your hands on, sort of slips out of your face like a slippery bar of soap.

You do your science separately, but when it comes to faith, you suddenly switch off all your questioning faculties.

I think they
[the bishops] are wrong...but I don't think they are insane.

If you disagree with something, then what you do is you come back and argue. You don't say "Oh, I feel insulted"; you argue...Religion has carved out for itself a special protected niche where instead of arguing it says "I am insulted or I am offended". I think that offense is what people take when they can't take an argument. It's a kind of last resort.

My interest in religion is actually a scientific interest...The fundamental question of religion, which is does god exist?, is a scientific question.

In America science is under attack from the right, which pretty much means the religious right.

Download the podcast of the interview here.

Disclaimer: The text presented here is my transcription from the podcast and may contain errors.

27 June 2007

We are with the stupid

So, what are we going to do with the stupid? is the question Michael Hanlon, the science editor of the Daily Mail in London, asks in a thought-provoking essay in the 23 June issue of the New Scientist. It hadn't occurred to me that those who are not-so-gifted may be subject to some sort of discrimination for being so.

In this case, the discrimination in question is neither government-sanctioned, nor is it culturally based. Most of us, including those who may be subject to it, may not even be aware that it exists, partly because it has arisen relatively recently as an inevitable product of our culture and society that are being guided increasingly by information and technology. While the smart move on with the times, those who are low on intelligence may be left behind, without proper education and decent jobs or unemployed, or worse yet, unemployable. Nevertheless, they are still part of the society and they get to vote. We cannot reverse our direction, but may be able to help them out before they are too far behind.

According to Hanlon, in the UK there may be 2 to 6 million people with IQ scores between about 70 and 85. In the U.S., the number would be higher, because the population is larger. The Census Bureau reports the total number of Americans in 2000 aged 15 to 74 as roughly 200 million. How do we decide how many of them are "stupid"? The IQ tests are controversial and problematic; one's IQ score, although it may have a strong genetic component, could improve with practice and education-if one gets it. Nevertheless, they are a convenient rough guide for intelligence, while keeping in mind that the threshold below which one could be considered stupid is arbitrary.

Assuming that in the general population the distribution of the IQ scores is normal, Hanlon's IQ range of 70 to 85 falls conveniently within 2 to 1 standard deviation units below the mean score of 100, implying that about 13.6% of the U.S. population aged 15 to 74 is expected to have an IQ in the range 70 to 85. That is approximately 27 million fellow Americans.

Shall we ship them all to Oodaaq Island? In a democratic society, it would be unthinkable to attempt to grade and treat the citizens according to their intelligence unless they required special care. In any case, who would do the grading (never trust any government or "authority" when it comes to such matters) and what would be the arbitrary cut-off points anyway?

Hanlon offers a more sensible solution, undoubtedly one of many one can think of: Education systems that properly value vocational skills such as caring, craft or manual work would be a good start. That might require an overhaul of the current education policies as well as the establishment of government-sponsored employment agencies specifically tailored for the needs of the less-skilled workers without attaching any stigma to being so. With proper training, the not-so-gifted could be employed even in service to technology and information, for example as data-entry or library personnel. And who knows, they could even get to serve as politicians.

26 June 2007

Today's long sentence

From The Dispersal of Shells by Harry Wallis Kew (1893).

It has 109 words.

25 June 2007

Don't go beyond the pink door!


Here I go again, getting myself into another Ölüm Tehlikesi situation for the sake of a photo-op. Like the previous one, this sign was also warning fools like me of imminent danger to life from high-voltage electrical machinery, in this case hidden behind a pink door.

The picture was taken at a university in Turkey last May. I won't post the photographer's name, who is affiliated with the school, in case what we did violated some rules and regulations, although the door wasn't even locked. Besides, it was painted pink! How can one take a pink door seriously regardless of how grave a danger may be lurking behind it?

And yes, that is the hat that makes me look like a scientist.

23 June 2007

Dissection in progress

For the last 3 days I have been dissecting a small land snail, an enid species (family Enidae) from Turkey. The picture below shows the entire body of the snail with nothing removed except its shell, most of which I dissolved away with acetic acid (I forgot to take pictures during that process). The twisted mass of white tubes on top of the body is the snail's genitalia.

The examinations of the genitalia help us distinguish between species. Evolution usually creates anatomical differences between the genitalia of different species. Such differences may decrease or completely prevent the mating of closely related species, thus, contributing to their evolutionary divergence.

The removal of the genitalia from small snails is not easy, requiring a lot of patient, careful cutting and teasing apart of tissues by a pair of steady hands manipulating tweezers with very fine tips. I do most of my dissections late at nite when I am relaxed and slightly sleepy after a bottle of beer.

The scale is in millimeters.

In the picture below the main mass of the reproductive organs of the snail is on the left, while the rest of the body is on the right. Obviously, the reproductive organs make up a significant portion of the overall body mass. That being the case, their energy requirement-during reproduction-must also be a significant fraction of the total energy budget of the snail.

The diversion of resources from one organ system with a high energy requirement to another organ system also with a high energy requirement must be one process that creates trade-offs during evolution. For example, when the members of a population of a snail species starts making thicker shells, they may become less vulnerable to predators. But at the same time, their reproduction may slow down and the number of offspring may go down. This compensatory trade-off arises, because energy and resources may have to be channelled from reproduction to shell-making. Ultimately, it is up to natural selection to pick between thicker shells or more offspring.


I still have to untangle the penis, epiphallus, appendix, vagina, etc., from each other without breaking anything apart and then spread them out and pin them down for examination and further photography.

22 June 2007

A primitive wingless insect from the bedroom

Among the many arthropods we willingly share our home with are the so-called silverfish of the order Thysanura. We leave them alone and in return, they provide me with occasional opportunities to photograph them.

This individual was about 10 mm long.

"They are odorless and harmless, and serve to remind us of how ephemeral we are-and how ephemeral our books and records are, for silverfish live on the sizing of paper and the bindings of books. I keep my American Scientist in the attic for the silverfish to eat, although I have heard that they do equally well on Playboy or The Watchtower."
Howard Ensign Evans, Life on a Little-known Planet, 1968

21 June 2007

How to tell Eobania vermiculata from Helix aspersa

In the comments to an earlier post about the snail Helix aspersa, a reader (Nemo Ramjet), who had photographed a live Eobania vermiculata, inquired about the differences between that species and H. aspersa (with apologies to non-Turkish speaking readers, I should point out that the subject comments and my answer were in Turkish). Both E. vermiculata and H. aspersa are edible species that have been introduced to places away from their original homelands. They are common in Turkey, where they are not native, in fields, gardens and ruins.

With a little practice, it is quite easy to tell the two species apart. There are many differences between their shells, but the most significant and the easily noticeable is the width of the body whorl, which is much larger relative to the width of the preceding whorl in H. aspersa than it is in E. vermiculata. As a result, the aperture of H. aspersa is also relatively wider than that of E. vermiculata.


The pattern on the shells of E. vermiculata almost always consists of brown bands with little variability, while the pattern and the colors on the shells of H. aspersa are more variable. Adult H. aspersa shells also tend to be larger than adult E. vermiculata shells, but size, in this case, is not always a reliable criterion to distinguish the 2 species from each other.

The variability of the patterns and colors of H. aspersa shells.

20 June 2007

Spreadsheet spread out


I have been working on a distribution list of the endemic land snails of Turkey. The list, a 45-page Excel file, will eventually form the basis of a talk I will be presenting at the upcoming World Congress of Malacology in Belgium as well as a manuscript, I hope.

Yesterday, I decided to go over the data to make sure everything had been entered correctly and accounted for. But it was difficult to go back and forth between the pages on the computer screen, so I decided to print the file out.

It turned out that a 45-page hardcopy of a spreadsheet was a real pain in the butt to manipulate. First, I had to align and loosely tape all the pages together. Then, I needed a wide enough space to lay the entire collection of pages out. I considered taping it on a wall, but, at the end, settled for the dining table.

I think it would have been easier to go back and forth between the pages on the computer screen.

19 June 2007

Some places haven't changed much

In Jak Deleon's bilingual (Turkish, English) book about Büyükada, the largest of the islands off Istanbul in the Sea of Marmara, there are photographs of several old post cards of the island. One of them, unfortunately an undated one, shows a portion of the east side of the island with the old Greek orphanage (arrow) visible on top of a hill in the back.


During my trip to the island with my friend Teri early in May, I had Deleon's book with me. I wanted to try to locate some of the scenery in the old post cards. So, as we were climbing up towards the hill on top of which is the Aya Yorgi Monastery with sticky rocks, we kept stopping and looking behind us to find a vintage point from where we could observe a scenery as close as possible to that in the above picture. But the pines kept blocking our view and this was the best we could do.


The old picture had been taken from a higher point. Otherwise, the scenery hasn't changed much; the orphanage is still there (more about that in a future post), although there appear to be a few more buildings and a larger clearance at the shore of the small bay in the foreground. Fortunately, the island has resisted development so far and the pine forests, despite occasional fires, still cover most of it. I wish I could say the same about Istanbul, the obscenely large city that is visible on the slopes of the hills in the background.

Railroad bridge graffiti


More miscellaneous graffiti:

Naughty mushroom graffiti

Cat graffiti

17 June 2007

Frog legs for lunch

My uncle loved fishing. Although we, his 2 sons and I, never developed much of an enthusiasm for angling, we would occasionally tag along with him. During one such trip many, many years ago in the countryside outside of Ankara, Turkey, my cousin Metin and I got some fishing gear and gave it a try. But instead of fish, Metin and I kept pulling large frogs out of the creek. Then, one of us had a bright idea: why not eat the frogs for lunch? My uncle had no objections (he was a cool guy).

Metin with one of the luckless frogs that became our lunch.

I don't want to try to remember how we killed the poor frogs before we chopped off their legs. We skinned the legs, skewered them on sticks and then roasted them over an open fire, while my uncle was cooking the stew he had prepared with the fish he had caught.


The roasted frog legs did taste good (like chicken?). Since then, I've had frog legs once, in a restaurant in New York several years ago. Those were a disappointment.

Would I eat them again? If I were starving in the wilderness somewhere I would, if I could catch them. But I wouldn't eat them in a restaurant, especially if they were wild-caught frogs. Do they have frog farms?

Yours truly in his underwear recovering one of the fish that had gotten tangled in the reeds. I think it was a trout.

16 June 2007

Saturday nite's beer review: Samuel Adams Cherry Wheat


This is an unfiltered wheat ale with a deep golden color and a pretty strong cherry aroma. The overall flavor is nice and smooth.

It is definitely a good beverage for a nice, warm summer evening.


Are we having fun yet?

Over the Hedge

15 June 2007

16 dead in Ohio

A small scraper or putty knife was an indispensable tool to loosen and remove squashed specimens from the highway surface.
Seibert & Conover, 1991

Untold numbers of animals perish while crossing highways. We notice mostly the larger vertebrates, but the majority of the casualties are probably invertebrates. During my childhood in Turkey many, many years ago, after every night drive thru the country side, the grille in front of our car would be filled with all sorts of dead insects. Alas, I never thought of removing those casualties to start a collection. Many of those species have probably become rare since then.

A study reported in the Ohio Journal of Science1 in 1991 claimed to be the first to tally invertebrate casualties attributable to collisions with vehicles. The authors, Seibert & Conover, collected all the dead invertebrates they found along a 1-mile stretch of a highway in Ohio during an approximately 14-month period.

They ended up with 1162 invertebrate specimens, of which 1069 were insects. Hymenopterans (bees, etc.), lepidopterans (butterflies and moths) and dipterans (flies) constituted the majority of the victims. Some of the collected specimens had been absent in the Ohio University insect collections. The authors, therefore, suggested that collections of roadkills should be included in faunal surveys.

Among the relatively small number of non-insect casualties were 16 polygyrid snails (family Polygyridae). I am sure many more snails as well as insects had been killed but not accounted for, because they either remained on the tires or windshields of the vehicles or were squashed beyond recognition.

In the half a billion-year old history of life, death by motorized vehicles came into play less than 200 years ago with the introduction of steam locomotives. Have any animal groups evolved defensive mechanisms to lessen their chances of getting hit by motorized vehicles since then? Collisions with vehicles may be a strong enough selective force to have affected the behaviors and agilities of animals, for example, squirrels, that live alongside busy roads.

1Seibert, Henri C. & Conover, James H. 1991. Mortality of Vertebrates and Invertebrates on an Athens County, Ohio, Highway. Ohio Journal of Science. 91:163-166. pdf

13 June 2007

Pollen of the eastern white pine

Among the items eaten by a slug from my backyard that was the subject of this post were some pollen that I had not bothered to identify when I was writing that post. A reader indicated that the pollen were the type made by pine and fir trees. There are indeed 3 large eastern white pine (Pinus strobus) trees in our backyard. Until about 2 weeks ago there were layers of their yellow pollen accumulating at various spots in the backyard.

But I wanted to confirm that the pollen from the pine trees did look like those from the slug's feces. So, yesterday I got some pollen from one of the trees and examined them under the microscope. Morphologically and dimensionally, they matched the pollen that I had observed in the slug's feces. Since there was so much pollen around that it is not surprising that the slug had eaten some. Whether or not they can digest the pollen is another question.

The pollen of the eastern white pine. They are actually yellow. The pollen on the right was 56 µm across. The pictures were taken with a light microscope.

12 June 2007

An ugly lady on the sidewalk

When I came across this creature, it was crossing a sidewalk hurriedly. Luckily, as I started fumbling with the controls of my camera, it found something edible and stopped. That gave me a chance to photograph it without having to chase after it. It didn't even mind the ruler I placed next to it.

The scale is in millimeters.

If I am not mistaken, this was a convergent lady beetle (Hippodamia convergens) larva. Compare my photos with this one.


11 June 2007

What the slug had eaten for dinner

Several days ago one night, following an afternoon rain, I went out into the backyard to check out the creatures. While the isopods were loitering in the bird bath, this small Arion subfuscus was crawling on a rock covered with green algae (cyanobacteria). Was the slug eating the algae? There was only one way to find out.


I brought the slug in and placed it in an empty plastic container with plenty of water to make sure it wasn't going to dry up, but, without anything to eat. About 24 hours later, there was plenty of slug poop in the box. I removed the poop and returned the slug to the backyard.

So what had the slug eaten for dinner? Its feces teased apart in a little drop of glycerol provided a partial answer. One needs to be a botanist and turn this into a major research project before every bit of matter in a slug's feces can be identified. I will do my best.


The above picture is an overall view of a part of the sample. As is typical with these slugs, this one had eaten a lot of different things, including both live (green) and dead (brown) matter. The long, brown twisted string-like material (arrow) is probably what is referred to as the liver string in the literature1. They are present in almost every fecal sample from slugs. When teased apart, liver strings do not yield anything identifiable, because, unlike the rest of the material, they are more or less amorphous and homogenous.


The four "large" objects in this picture are pollen (they are actually about 66 µm long). I can't tell which plant they came from. The much smaller and abundant brown things (red arrows) are probably fungal spores.


Here are 2 close-up shots of what were live plants before they were eaten. The fragment on the left appears to be a piece from a leaf.

If the slug had eaten algae from the rock it was on, what would they look like in its feces? To help me answer that question, I scraped some algae off the rock and examined them under the microscope. Fortunately, the cells of cyanobacteria are easily distinguishable from plant remains, because the former are spherical. The picture below shows one such cell (diameter: ~16 µm) from the rock sample.


There were many similar looking cells in the feces of the slug. Compare them with the plant material in the picture above where the fragments have more irregular shapes. Also visible in these photos what appeared to be fungal hyphae. These slugs indeed feed on whatever comes their way, even dead earthworms.


1Runham & Hunter. 1970. Terrestrial Slugs. See p. 57.

09 June 2007

The thing on the bathroom mirror

I was busy barbequing chicken kebabs late this afternoon when my wife came over and announced a minor crisis: "I think there is a tick on the bathroom mirror". I took a look at the creature and confirmed her tentative identification. The patterns on the tick's back looked unusual, so I left to get my camera and a vial of alcohol.


A quick search on the Internet identified it as a female American dog tick, (Deracentor variabilis). It definitely looks different than the deer ticks that I am more used to seeing around and on me.

I haven't the slightest idea where it came from and how it ended up on the side of the bathroom mirror. It is now resting in alcohol.

Photographs of and information about American dog ticks are available here. here and here. They apparently transmit Rickettsia rickettsii, the bacterium that causes Rocky Mountain spotted fever in humans. Just what we needed.

08 June 2007

He ain't got no body


These are the wings of a male cabbage white (Pieris rapae) that I found in the woods today. The butterfly's body was probably in a bird's stomach.

07 June 2007

Fly away birds, here come the isopods

The main function of the bird bath in our backyard is to provide water for the neighborhood birds. But birds are not the only animals that utilize the bath. I have already written about the very abundant bdelloid rotifers that live in the water. The other nite I witnessed another group of animals apparently partaking of the water that was being offered. They were isopods.

In this and the next photo the red dotted lines mark the approximate position of the top of the water.

What were the isopods doing in the bird bath? It had rained earlier and at that time (this was around 2130 hours) the ground, the grass and all the other plants were wet. If the isopods needed water, they certainly didn't need to climb all the way up to the bath, which is 60-70 cm above the ground. Moreover, how did they know that there was water up there?


Terrestrial isopods evolved from marine ancestors (more on isopod evolution here). So I thought maybe they were reenacting the emerging of their aquatic ancestors out of the sea onto the dry land millions of years ago. But later when I saw the next picture, I changed my mind. I think they just like to look at their own reflections in the water.


06 June 2007

A mummy on the sidewalk


I saw this thing on the sidewalk yesterday. I was about to step over it thinking it was just another piece of lifeless debris when I realized it was not an ordinary piece of lifeless debris, but an ex-frog, a tiny dried-up lifeless frog. It was being ignored even by the ants. I couldn't have ignored it. So I photographed it. My finger provides a scale.

The closest pond was across the street about 50 m away. It presumably came from there. But how?

Surprisingly, today, about a day later, it was still at the same spot. It was obviously not yet ready to return to life.


05 June 2007

Cluster analysis - part 2

A cluster analysis uses various algorithms to form groups of data points. It does not, however, assign much of any significance or meaning to the resulting clusters. Nor does it explain the processes behind the formation of those clusters, even if they had a lot of significance. The explaining is up to the scientist.

In yesterday's post I presented the results I had obtained with artificial data. I also implied that a cluster analysis would be most successful if the scientist already suspected some sort of clustering in the data. Yes, it seems like a bit of a circular process.

One (other) problem with any type cluster analysis is that even when no meaningful clustering is expected in a data set, a cluster analysis is likely to come up with clusters. Today I will demonstrate this by applying clustering analysis to real data.


This is a histogram of the distribution of shell lengths of 54 live Vertigo pygmaea from my backyard. These types of measurements are usually distributed normally or near-normally. There is really no requirement that they be normal, but because many independent or almost independent factors contribute in an additive fashion to the development of the measured values, the resulting distributions usually approach normality.

The histogram for the heights of Vertigo shells also appears normal, although its tails seem to be extended a bit too far out in either direction. The 2 shortest shells were 2.75 and 2.25 standard deviation (SD) units away from the sample mean, while the 2 longest shells were 2 and 2.5 SD units away from the sample mean. In a theoretical normal distribution, only about 5% of the data points are expected to be more than 2 SD units away from the mean. So in a sample of 54 specimens, the presence of almost 4 measurements outside the 2-SD limit seems unusual. But, as I explained above, snails don't have to stay within the boundaries of any theory and may behave any way they wish. Besides, there may also have been measurement errors.

These measurements belonged to one species and were obtained from a sample of shells collected at the same time from a very small plot. So there really was no reason to expect any clustering in the data. But here is the clustering dendrogram PAST created with this data set.


You see the analysis comes up with all sorts of clusters. What it seems to be doing is that it is grouping every 2 data points that are closest to each other as a cluster and then clustering those with other clusters or points. As a matter of fact, that is exactly how clustering algorithms work.

Interestingly, the 2 clusters that stand out most from the others, and which I colored red and green, correspond to the tails of the histogram. The red one includes the 2 shortest shells and the green one the 2 longest shells. These are, however, artifactual clusters without any biological significance. The lesson from this exercise is that one needs to be careful about how one interprets a dendrogram. Once again, it is almost as if one needs to have some idea of whether or not clusters are expected before the analysis is performed.

04 June 2007

Cluster analysis - part 1

I don't know much about cluster analysis. In fact, I know so little about it that I shouldn't even be writing about it. But I am learning about it and one way to learn about something is by writing about it on one's blog. That helps because, unless you want the entire world to think what an idiot you are, before you write about something new, you study the subject matter and then put in your blog post only those things that you think you have understood and hope for the best.

Another way of learning about something like doing cluster analyses is by doing simulations. So, to carry on a cluster analysis simulation, I created a data set of 25 numbers intentionally grouped in 2 groups. What could such a group of numbers represent in real life? Well, they could be the measurements of a body part of a sample of organisms, for example, the lengths of snail shells.

10.1, 10, 10.2, 10.1, 6.4, 10.0, 6.2, 5.9, 10.4, 6.0, 6.0, 6.1, 10.3, 10.2, 6.3, 6.2, 10.0, 10.3, 6.1, 6.0, 10.4, 10.3, 6.0, 6.1, 10.0

I just made these numbers up so as to have 2 sufficiently distant sets of numbers. Even a casual glance at these numbers will make one suspect that there are indeed 2 clusters.

6.4, 6.2, 5.9, 6.0, 6.0, 6.1, 6.3, 6.2, 6.1, 6.0, 6.0, 6.1

10.1, 10, 10.2, 10.1, 10.0, 10.4, 10.3, 10.2, 10.0, 10.3, 10.4, 10.3, 10.0

Obviously, in this case one doesn't need any sophisticated statistical tests to confirm one's suspicions. Nevertheless, a quick and easy test is to compare the confidence intervals (CI) of the means of the 2 groups. The 95% CI of a sample mean is calculated using its standard error and it is the interval in which the population mean is expected to be 95% of the time. In this case, the CI of the mean (6.11) of the 1st group is 6.02 to 6.20, while the CI of the mean (10.18) of the 2nd group is 10.09 to 10.27. The higher limit of the CI of the 1st group doesn't even come close to the lower limit of the CI of the 2nd group. So, yes, we can be quite confident that we have 2 non-overlapping clusters.

Now, let's do a cluster analysis with this set of numbers. Luckily, there is available a free and fairly user-friendly statistical software called PAST (Palaeontological Statistics) that does cluster analysis. Here is the dendrogram I got back from PAST for my data set.


The vertical axis gives the similarity values that PAST calculated using an algorithm called "unweighted pair-group average" the details of which need not concern us here. Note that the similarities have negative values; the larger the negative number at the branching point of 2 clusters, the less similar they are.

In this dendrogram there are 2 well-separated clusters of numbers corresponding to the 2 groups. But what about all those other clusters within each main cluster? They have relatively small similarity values at their branch points and appear to be are artifacts of the analysis; we are going to ignore them.

The next post in this series will apply cluster analysis to real data.

03 June 2007

Gastropod's gastronomy


Salmon turbans with papaya salsa; basmati rice with spinach, green onions and lime juice; green olives stuffed with red peppers and garlic.

02 June 2007

Turtle and its hitchhiker

When we are on an expedition in Turkey we need one of those warning signs behind our car: "This vehicle makes frequent stops". We stop not just to collect snails but to take pictures, to drink tea at coffee houses, to listen to roadside musicians and to do a million other things. Almost everything alive that crosses our path, not just animals but also interesting trees, is an excuse to apply the brakes, followed by a bunch of us rushing out of the car with cameras. No wonder it usually takes us forever to get to where we are going.

The turtle was ~27 cm long. Photo by Ümit Kebapçı.

This turtle (Testudo graeca) that we encountered last May in southwestern Turkey in the middle of a high mountain road was no exception. After we photographed it, I decided that it was best for its safety-even though we were not on a busy road-to move it to a more natural spot. While carrying it, I saw a tick attached to the rear end of the turtle's shell.


According to this article, ixodid ticks (Ixodidae) are common on these turtles. The normal feeding location of the ticks is the legs of the turtles. But this one was, for some reason, on the outside of the shell. Perhaps it had just landed on its host not yet moved to the underside of the shell. Not wishing to interfere with the course of a natural event, I left the tick where it was.

The tick was ~5 mm long.