May
18
2009

Dolphins Shed Innocent Guise and Maim Again!!

Baby Tucuxi, unaware of impending attack...
Baby Tucuxi, unaware of impending attack...Courtesy Matt Walker

Reading about mutinous mammals is waaaay better than writing the final paper of my undergrad career! Agreed? Yes, well to the point. Now I've heard that dolphins will bite ya if provoked, but that even that is extremely rare.

It is not uncommon for mammals to practice infanticide. It is practiced for a variety of reasons. Males may attack young of their own species so the mother is more receptive to further reproduction from that male. It is also practiced when resources are low and a groups well-being is in danger from lack of food. Both males and females of a species will practice infanticide.

Among their scientific class Cetaceans, a class including dolphins, whales, and porpoises violent behavior including infanticide is very rare and largely undocumented...until now!

Tucuxi Dolphins, native to the Amazon basin were observed practicing infanticide in Brazil by Mariana Nery, of the Southern University of Chile in Valdivia, and Sheila Simao, of the Federal Rural University of Rio de Janeiro, Brazil. Adult male Tucuxi are known to be aggressive but they rarely exhibit this behavior towards younger individuals. Nery and Simao observed six adult Tucuxi separate a newborn Tucuxi calf from its mother. They proceeded to ram into it, hold it under water, and toss it into the air. When the mother attempted to intervene four of the males herded her away. While the adult males attacked the calf the mother floated on her back. This behavior indicates either passiveness, or more likely a signal that she is receptive to sexual behavior. I believe she did this to distract the adult males from injuring or killing the calf, and to let them know she could reproduce again. To no avail. Sadly, the mother was seen days later without her calf.

Your Comments, Thoughts, Questions, Ideas

Diane W's picture
Diane W says:

This was very interesting! I do have a new sight that I will check ou often.

posted on Mon, 05/18/2009 - 9:48pm

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