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Shelled Wonders – Turtles and Crayfish

June 5, 2007

box-turtle-2Chers Amis,

Much to my children’s delight, we enjoyed visits from two well-armored guests Monday, Natalie, an Eastern Box turtle and One Claw, a common crayfish.  Before breakfast even made it to the table, Caddie and Scarlett were out in the back yard scouting for visitors and came running back cradling Natalie. This lead to immediate nature study
and cold, hard waffles. C’est la vie au moulin.crayfish

Turtles are wonderful subjects for nature study and sketching, the embodiment of patience and fortitude – and they don’t move around too much. Crayfish, however, are a bit more active and offer interesting opportunities to practice observation skills.  One resource that we use with almost every nature encounter is Anna Comstock’s Handbook of Nature Study. It had some particularly good ideas for crayfish.  Here are some ideas and links that you might find useful in getting to know the shelled wonders in your area  and identifying them as individuals. Eastern_box_turtle

  • Take pictures: We have seen a total of four Eastern Box turtles (EBT) –Terrapene carolina carolina on our property this year and have taken numerous photos of each turtle’s carapace (top shell) and plastron
    (bottom) in order to correctly determine the turtle’s age and sex and
    to aid in future identification.  By comparing the yellow and black
    patterns on Natalie’s scutes or
    scales with the pictures in our “Box Turtle” file, we were able to
    confirm this was the same female turtle we found in late May fresh from
    a spash in a puddle.

As we were reviewing our photos, Natalie sat
motionless on my mouse pad until her curiosity urged her to unhinge her
shell and poke her yellow spotted neck out of her armor.  Seeing no
threat and a wild mulberry to one side, her legs emerged and she turned
to face the monitor.  We wondered what she though of our turtle slide
show passing before her brown eyes.  Crayfish are less open to being handled so a quick series of photos can help enormously while avoiding nipped fingers.

  • Make a sketch and take measurements: I have included a page from my nature notebook from 2004.  You can see that I did not have a chance to finish the drawing (I wonder why :-), so I concentrated on capturing the ‘turtle specific’ patterns on several scutes for future tracking. Recording measurements will allow you to compare males to females (nice graphing opportunity), track growth over time and compare size to age.
  • Take Notes: One idea I have seen, but not implemented yet, is to have an index card for each ‘known’ creature on which you paste a photo and make notes on each sighting, where was Natalie found?  Beneath the back path footbridge?  In the front garden? What time of day and date?  Does she show any new markings – ie.e. cracks, scars, etc. Has she grown? These are all things we record on nature pages, but we don’t have time to make a new drawing each time.  I like this idea and think I will set the girls on making cards for our current turtles:  Natalie, Granpa, Ridgeback and Three Leg  and the crayfish, One 100_1245Claw and the Gladiator.
  • Look closely for gender identification and age indicators. What color are the turtle’s eyes? Male EBTs have red eyes while females’ eyes are brown. This is a photo of Granpa.  What red eyes you have! Turn the turtle over gently.  100_1235Is the plastron flat or slightly ‘dented’/concave. Male plastrons are concave to facilitate reproduction. Note the number or rings on each scute. Like trees, EBT add approximately one growth ring each year.  As turtles age, however, they wear the rings smooth.

Here is a p100_1241icture  Granpa. Compare it to that of Natalie at the top of the page.  Notice differences in rings and smoothness.

Carefully look at the underside of the crayfish Do you see a small opening between the last pair of legs? Female Or do you see a small additional pair of legs folded up on the abdomen?  Male.  Visit Bev at the Burning Silo for a fantastic primer on crayfish that included annotated photos of male and female crayfish.  She also has the nicest nature blog I have seen and the funniest description of why she chose her blog name.

Hope you all have fun getting to know these creatures. We sure have!


9 Comments leave one →
  1. hélène permalink
    June 5, 2007 5:29 pm

    un autre site intéressant !

  2. June 6, 2007 8:57 am

    Wow! Your drawings… your finds… your school… Just wow! 🙂

  3. June 11, 2007 9:52 pm

    Wow! I wish I’d thought to turn our turtle over and get a picture, not to mention make a sketch and measure him/her. I will next time! Great site.

  4. betty permalink
    June 12, 2007 9:07 am

    What a great, fun lesson! Now that’s the way to learn!

  5. June 15, 2007 7:25 pm

    Oh Marjorie,

    We all had a good time reading about your annual visitors!! We have a few that come into our backyard every year and we welcome their visits. We didn’t know about the markings on the scutes being individual *finger prints*. We’ll have to pay more attention next year.

    Last year Dave almost ran over a new baby with the lawn mower. We really enjoyed observing and drawing it in our nature journals. The shells of the new little ones is so ornate and beautiful!

    Thanks for sharing.

  6. June 16, 2007 4:29 pm

    Great post on gathering some good scientific data on common animals. Just to let you know, that the throat markings on frogs often can be used to distinguish individual animals. With digital pictures being so cheap and easy to work with, if you can get several pictures of the animal you may be able to distinguish it later.

    Of course, sketching is also a great skill to have and, as a biologist, I wish I could sketch better.

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