Tuesday, May 1, 2012

The Prehistoric Turtles of White Rock Lake, Dallas

If there is an exposed log in White Rock Lake, it will soon become littered with a seemingly endless number of basking turtles, both big and small. Turtles are ectothermic (cold blooded) which means that they rely on the temperature around them to regulate their body temperature. Although turtles are mainly aquatic, basking on a log or rock is a way for them to warm their bodies.

Turtles basking on a log at White Rock Lake, Dallas, TX
Turtles basking on a log at White Rock Lake, Dallas, TX

White Rock Lake has a number of different species of turtles: Red Eared Slider, Yellow Mud Turtle, Missouri River Cooter, the Common Snapping Turtle, and the Mississippi Mud Turtle.

The turtle in the image below is a Missouri River Cooter (Pseudemys concinna metteri). It's a strong swimmer with webbed hind feet. Their shells are dark, and some Cooters have the most exquisite, intricate yellow patterns as you can see from the image below.

This turtle was swimming in a creek that feeds Dixon Branch Creek. Luckily, the water was clear so the pattern is visible.

A Missouri River Cooter turtle at White Rock Lake, Dallas, TX 
A Missouri River Cooter turtle at White Rock Lake, Dallas

Did you know that turtles are some of the oldest reptilian species on the earth?

Turtles have remained virtually unchanged for 200 million years or more, so show these critters some respect! They date back to the dinosaurs, and still retain many traits that they used to survive back then. 

Fishing is popular at White Rock Lake and quite often turtles will bite on a baited fishing hook. The poor turtle below has a fishing hook stuck in its mouth! This image was captured from a bridge in the park that spans Dixon Branch Creek.

This poor turtle in Dixon Branch Creek has a fishing hook stuck in its mouth
This poor turtle in Dixon Branch Creek has a fishing
hook stuck in its mouth

Turtles may spend most of their lives in water, but they are air breathing animals and need to come to the surface to breathe from time to time, as the Red Eared Slider below is doing. This image was captured from a bridge in the park that crosses Dixon Branch Creek.

Red Eared Slider turtle coming up for air at White Rock Lake, Dallas, Texas
Red Eared Slider turtle coming up for air at White Rock Lake

All turtles lay eggs. It is interesting to note that with several species of turtles, temperature in the nest will determine the dominant gender of the young: warm nests producing primarily female turtles, and cooler nests producing mainly males.

Several smaller turtles sharing a tree limb in Sunset Bay White Rock Lake, Dallas, T
Several smaller turtles sharing a tree limb in Sunset Bay
White Rock Lake

The Red Eared Slider (Trachemys scripta elegans) seen below is a medium sized turtle that loves to bask in the sun, but is very difficult to approach. When they see you coming, they quickly disappear into the water. They have a prominent patch of red on both sides of the head. They are sometimes referred to as a “pond slider.”

Red Eared Slider turtle basking on a log at White Rock Lake, Dallas, TX
Red Eared Slider turtle basking on a log at White Rock Lake

Turtles live for a long time, and some of them live for longer than 100 years.

A turtle at Sunset Bay, White Rock Lake, Dallas, Texas
A turtle emerges from the murky depths of Sunset Bay, intently
watched by a curious goose



2 comments:

  1. "Turtles have remained virtually unchanged for 200 million years or more,..."

    u sure about that figure? (lol)

    i know it's been about 4 thousand years 6 thousand tops. before that, they didn't even exist, but then your "sure" it was more than a million. We seem to disagree. We're going to find out who's right one day.

    ReplyDelete
  2. You can find out more about prehistoric turtles here: http://dinosaurs.about.com/od/otherprehistoriclife/a/Prehistoric-Turtles-The-Story-Of-Turtle-Evolution.htm

    " ...turtle evolution is an easy story to follow: the basic turtle body plan arose very early in the history of life (during the late Triassic period), and has persisted pretty much unchanged down to the present day .."

    "Odontochelys prowled the shallow waters of eastern Asia about 220 million years ago ..."

    "By the early Jurassic period, about 200 million years ago, prehistoric turtles and tortoises were pretty much locked into their modern body plans ..."

    The article has many links that will enable you to do some meaningful research.

    ReplyDelete