On October 28, 2006, fisherman that were capturing individuals of a group of 118 bottlenose dolphin (Tursiops truncatus) near Taiji, Japan for exploitation in aquaria noticed something peculiar about one of the captured individuals. While the vast majority of dolphins have only two front flippers one particular female had a set of small pelvic flippers. Many whales (particularly baleen whales) have the vestiges of hips and leg bones inside their bodies but a whale with external pelvic fins is an even rarer find. A new paper released online in the journal Marine Mammal Science provides an update on this individual, dubbed AO-4 and now residing with another captured pod member (AO-1) at the Taiji Whale Museum.
Unfortunately that’s about all the new article says. The short communication ends with a call to organize a team to undertake a detailed study of AO-4;
In order to conduct wider interdisciplinary research, we wish to organize a project team to study the comparative morphology, genetics, physiology, and life history of these two dolphins involving interested scientists from various research fields. We believe that keeping AO-1 and AO-4 together will be useful for comparative studies and to maintain the long-term mental health of this unusual dolphin.
I definitely want to find out more about AO-4 and why she has pelvic fins (their internal anatomy, the changes during development that could have led to their expression, etc.) but I have to admit that I am a bit saddened by the story. After my last trip to Sea World in 2006 I’ve become especially concerned with how cetaceans are kept in captivity and I can only conclude, particularly in the case of marine amusement parks, that cetaceans are often kept in an ethically unacceptable manner. (See the particularly egregious case described in Lolita: Slave to Entertainment as an example.)
Many people say that they are amused by the beauty, power, and intelligence of cetaceans, but these fantastic animals are kept in cramped, plexi-glass lined pools that do not in any way even approach their natural habitat. I know I would go out of my mind if I was stuck in a concrete room every day of my life, and I do not understand why we see fit to confine some of the most intelligent animals on the planet in such unacceptable conditions for our amusement. Cetaceans in captivity often suffer from physical and mental illness, becoming bored and even aggressive towards trainers, their tank mates, and even themselves. Being that “Shamu” is Sea World’s cash cow, though, I don’t see them changing their ways anytime soon.
A bottlenose dolphin (Tursiops truncatus) with fin-shaped hind appendages