dijous, 24 d’octubre del 2013

Why does Clemmys guttata have spots?

When I look for the Clemmys in the pond, I look for yellow spots.  When they swam under the ice, it was the spots that took my attention. The spots make finding the Clemmys easier. Yellow is the color that constrasts more on black, to the extent that other animals, such as wasps or fire salamanders,  use this combination as an aposematic coloration, a warning to potential predators.
Other turtles also have spotted carapaces, such as Emys orbicularis or Emydoidea blandingii. Are the spots  just a nature caprice or there is another reason for it?


When they are wet the colors are more stunning

Yellow spots help me to find them when they are inside the filamentous algae




Good camouflage, but do the spots help in it or just  do the opposite?

When they are dry the color is duller. Good comouflage on this substrate


The predominant color in Clemmys guttata is black, and it is probably related with thermoregulation. They use to live in cold places and it is one of the first turtles to emerge in spring. Then the black color is an advantage.

Regarding the yellow spots, in the book Turtles of the United States and Canada it says they could imitate duckweed  (Lemna sp) and other acquatic plants common in the wetlands that this species inhabits, making detection by predators more difficult. I found a paper on the subject





Looking for information about camouflage, it says that in very vegetated habitats, such as jungles or forests, the combination of filtered light with the ground, plants, stones, trunks...makes a spotted or stripped animal  less defined, its shape fades with the environment (young deer, felines...)

Is it possible then that the spots are useful for camouflage? In the pond where I have them they have the opposite effect, they make the turtle more visible. Do they make them more unnoticed in their natural habitat? I don't have the answer, but to assess camouflage you have to see the animal in the habitat. I saw it very clearly with   Testudo hermanni. This tortoise in a garden stands out, but in the habitat it is different




















In the middle, it is difficult to see its shape






They are not always so well hidden, but they still ressemble the tones of the environment.






So, it would be interesting to see the Clemmys in their habitat, underwater and in land, to check if the spots help to make them unnoticed.

I have seen some pictures of the different type of wetlands in internet: vernal pools, marshes, swamps, bogs, fens... Some links with descriptions and pictures  of the different types.


It would also be interesting to see things from the perspective of their predators (racoons, skunks, otters...). We are a very visual species, we see in detail and many colors. Other species see differently. In a conference done  by the Societat Catalana d'Herpetologia (SCH), one talk was about sight in wall lizards. These lizards, like chelonians, see down to the UV spectrum. Females see tones in males that we don't perceive. The speaker talked about antropomorphism by omission: the one that takes place when by deffault we assume that the sensory abilities of the species that we study are similar to ours.
This is a link to the study, but I only found it written in Catalan.

http://roderic.uv.es/bitstream/handle/10550/23877/tesi_GuillemP%C3%A9rez_deLanuza.pdf?sequence=1

I remember a conversation with a  biologist that studies T. hermanni in the wild. Once they used trained dogs to count the number of tortoises in a territory.  He realized how differently do humans and dogs use vision. The dog was searching by scent and although it often passed near tortoises that the human eye catched easily,  the dog didn't see them. He found them by scent.
Something similar happens with cats.  Sometimes a cat sees a dog at some distance and stays completely quite, frozen. Very often the dog passes by without seing it. We, humans, use to see it.

dimarts, 15 d’octubre del 2013

Clemmys guttata (Schneider 1792): Etymology

In this website I found the etymology of the name Clemmys guttata. It says that Clemmys comes from the greek Klemmys (tortoise) and guttata from the latin gutta (gout)


Regarding Klemmys I coudn't find anything else, but regarding gutta, I found this interesting site


Interesting the botanic use of the word guttate for a leave with spots that look like water drops 

And looking for the origin of words, I wondered who was the Schneider that described Clemmys guttata for the first time in 1792. It was   Johann Gottlob Theaenus Schneider


But Schneider classified Clemmys guttata as Testudo gutatta. According to wikipedia the genus  Clemmys appeared in 1828 thanks to  Ferdinand August Maria Franz von Ritgen


It is also interesting the etymology of the word tortoise. Tortoise comes from latin tartaruchus that comes from the greek tartaroukös. Tartaroukös comes from Tartaros (hell) and Ekhein (inhabitant). People saw tortoises coming from underground or the mud of a pond and decided to call them creatures from hell, maybe not exactly a devil but anything good.

dimecres, 2 d’octubre del 2013

Growth

The male born in August 2011 is growing nicely. It looks as though new spots are appearing in the growth lines of the carapace, only on the marginal areas. 






Its tail is still very thin and the chin and face are not dark yet.








Although this is a Clemmys blog, today I will post some Testudo hermanni hermanni pictures.
Catalonia has a native population of the western subspecies. It is very protected and it is forbidden to keep Testudo hermanni,  never mind if they have been captive bred and have their CITES or they belong to the other subspecies, Testudo hermanni boettgeri.

The Catalan Environmental Department allows privates to collaborate in a captive breeding program of this species if some requirements (space, climate, security measures...) are achieved.  The CRARC are the ones that inspect the facilities and organize and control the captive breeding program. The animals that privates obtain are used in a reintroduction program in areas from Catalonia where this species lived before. They are not used to reinforce the places where the native species still survive. The CRARC are the ones that run this program, and the ones that organize and control the privates collaboration.
They borrowed me two males and three females, but the idea is to have 2 males and 8 females. They are kept in two separate groups.


Female with balearic fenotype


The key hole spot in V5, characteristic of this subspecies



This female has some pyramiding from previous owner (it could be a decomised animal)
This summer they have layed 2-3 times and the nests had between 4-6 eggs. I didn't notice some nests, but I knew they had layed for palpation. Most nests were in full sun but near the roots of plants and small bushes.

A nest on the top.middle of the picture, the ground with a different color
A picture nearer. The ground in the laying area is "sauló"
Another nest, under my shadow
Picking up the eggs of a nest

To increase the chances of success I incubated the eggs of more or less the half of the nests in a Jaeguer incubator.
For some reason, the eggs incubated naturally failed. The place where I have them falls in the potential natural range for the species, so I thought it was strange.
For comparison all the eggs in the incubator hatched. I know what to do next summer.




You can see the yellow spot on the face, characteristic of this subspecies
They are fed only weeds. This picture if from September the 30th, a very warm September (28ºC at noon)


I bath them so they can hydrate, but in hot days, I sometimes water the area with the goose. And they do the same that they do in a summer thunderstorm in the wild, they quickly drink from the pudles before the water filtrates.


 I will keep them untill they are more than 10 cm., so they pass the most vulnerable years. Then they will be released and they will be exposed to forest fire, predators (specially wild boars), humans... A few of them will reach adulthood, maybe none. 

I know there is a contradicion here. For one side  I keep chelonians for hobby, and this hobby is one of the causes of wild chelonian population depletion. On the other side  I collaborate in a breeding program to help the tortoises in the wild. Contradictory, like human nature. 

dimarts, 6 d’agost del 2013

Another surprise

There was finally a second clutch of three eggs on July the 10th. I didn't see the turtle nesting, it was next morning when I felt on palpation that she didn't carry the eggs. I looked for the nest and I found it in the place she usually chooses. There were three eggs.
 
And yesterday, on August the 4th, the first clutch eggs  hatched after 50 days at 30ºC.
 
First hatchling with tiny spots

Second hatchling
 

The third hatchling picture was very bad.

 
But this was not the surprise of the day. The susprise was that the same day the female started digging a nest for a third clutch. A clutch in August!
 





 
 
 
 



I don't know why she nested so late. The main difference with previous years it that this July has been cooler and much more rainy than usual, but I don't know if this explains a third clutch.
Could it be that I didn't notice this in previous years?
What I know for sure is that it is fantastic when they do unexpected things. Certainly this is not a boring thing to observe this species behavior.
 

dilluns, 17 de juny del 2013

Eggs 2013

This Saturday at  19:39 the female was nesting. I couldn't watch her because I had to leave, but I have some pictures. The temperature was nice, 24ºC, maybe this explains why she was nesting so early (she usually nests at night). Two years ago she also nested in the afternoon.
 The hole was nearly finished, so I guess she started between  18:00 and 19:00.





Next morning you could only see this



At 3 cm the eggs appear. Some years ago I mixed some small size sand with the earth, this helps in the nest excavation.





Two of them were in a nearly vertical position




The hole once emptied. The ground was at 4 cm.

In vermiculite, ready for the incubator. I put them in the same position, but I don't think it happened anything bad if I had put them horizontal.
 
This time there were three eggs. In previous years she had done 4 eggs in the first clutch and 3 eggs in a second clutch. I was expecting this clutch because I palpated the eggs some days ago, but I wonder if it could be a second clutch. I could have missed the first one. In previous years she had nested in May and we are in the second half of June.  I have not palpated her regularly because I didn't want to disturb her too much. So, it could be that there is a first clutch somewhere.
 
The new couple is very shy. The pond is in a very quiet place and instead of becoming tame, they are becoming wild. When I get close to the pond I just see them throwing into the water, just like frogs do.
There is plenty of duckweed in the pond now. It occupies all the surface excepte the moving water created by the aerator.
I have put some fish to avoid mosquitoes. It is not the native mosquitoes that worry me, but a relativelly new mosquito, the "tiger mosquito" from Asia (Aedes albopictus) that came in 2004. This one stings during the day, an important difference with the common mosquito when you want to watch  the turtles . The sting is also more painful and lasts for longer. In other countries it acts as a vector of dangerous human diseases, something that does not happen here fortunately, at least until now. 
 
A green carpet
 
 
 
 
 
 
The few pictures I could take before it hide
 
 
 
The duckweed tells the stone they use for sunbathing