Friday, August 12, 2011

Fond Memories Of A Very Old Shark

Tennessee Aquarium staffers were saddened by the loss of one of our bonnethead sharks today. For the past couple of weeks, we have been celebrating this “grand-daddy” of bonnetheads. You should have seen senior aquarist Rob Mottice while he talked about bringing this bonnethead to the Tennessee Aquarium from Florida in 1991. His eyes would light up and he would get a big smile on his face as he recalled putting this particular fish on exhibit.

As far as we know, this male was the world’s oldest of this species on public display. He was estimated to be 20 to 22 years old. (Scroll down for the complete story.) At least one shark researcher was interested to learn that our shark lived such a long life. Even though sharks on exhibit live longer than their wild counterparts, this new “record” adds to our understanding of bonnetheads. Will another one live longer on exhibit or an even older tagged shark be caught?

Up until his death, this shark seemed as active as the day he arrived at the Aquarium. So it appears that his advanced years finally caught up with him.

A technique called vertebrae ring analysis can be used to determine the exact age of sharks in the wild. Like tree rings, shark vertebrae exhibit growth rings that can be counted to tell how old the animal was. However, it’s believed that these growth rings are influenced by seasonality, so a shark on exhibit may not lay down such rings. We are going to attempt to have an expert examine this shark’s vertebrae. If growth rings appear in this case, our bonnethead may add a little more to our knowledge about this species.

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