Cold stunned hybrid sea turtles

MH-08-151-Hy: Our sole hybrid turtle this stranding season.
It is likely a cross between a loggerhead and Kemp's ridley sea turtle.

In Dr. Innis' 2008 cold stun season summary report he mentioned we had one hybrid sea turtle. For those of you not aware of hybrids they are the offspring of two separate species. Probably the most famous hybrid is the mule, an offspring of a female horse and male donkey. Typically hybrids are sterile however there have been some cases of hybrid sea turtles producing fertile eggs.

This year's hybrid sea turtle we guess is a cross between a Loggerhead turtle and a Kemp's ridley turtle. We will not now the exact species until we get genetic results back from this turtle. With that information we will be able to tell which species was the mom and which species was the dad.

So ... how can we tell that a turtle is a hybrid? After seeing so many turtles that come in extremely debilitated we will occasionally see an animal whose appearance does not look quite right. It may have a body that looks like a loggerhead but th e face has a bit of ridley to it. Or possibly a turtle that looks like a green sea turtle but has overlapping scutes like a hawksbill. After some debate amongst staff and volunteers on whether or not we think a sea turtle might be a hybrid we then set off to determine hybridization by counting different sets of scutes. Scutes are the bony "scales" on the sea turtle. Each species has varying numbers and qualities of scutes.
The turtle on the right is a hybrid Hawksbill/Green sea turtle. One of the giveaways is that the scutes are overlapping. We use an identification key to help us determine which turtle has which set of scutes. Do they overlap, what coloration, how many scutes should the turtle have? Seaturtle.org has a great identification key and it can be found at here (pdf) . You can see from the turtle, 02-833-Hy, there are only 4 costal scutes (the larger scutes that run on either side of w here the "backbone" would be) this is indicative of a green or hawksbill sea turtle but when you look at the prefrontal scutes on the head this is not what a green sea turtle or hawksbill would have. The head looks very much like a loggerhead. After getting genetics back on this turtle we found out the mother was a loggerhead and the father was a green sea turtle.
MH-02-833-Hy is a hybrid of a Loggerhead and a Green sea turtle.

The one hybrid from 2008 is still recuperating at the University of New England's Marine Animal Rehabilitation Center in Biddeford, Maine. From reports it is doint well and getting ready to be released this summer


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