Dear MARMAMers: As some here may know, SeaWorld has launched a new Twitter campaign, "#Ask SeaWorld." The link below takes you to a March 28 question and response from the related website. http://ask.seaworldcares.com/?p=276
From my knowledge of the literature and my time in the field, I know that killer whale teeth generally do not suffer severe apical wear (and only very rarely exhibit breakage) and when they do, this wear occurs at the population level and is associated with prey type (e.g., in the Pacific offshore ecotype, severe tooth wear is associated with feeding on sharks; Ford et al. 2011) or feeding method (e.g., in Type 1 North Atlantics, severe tooth wear is associated with suction-feeding; Foote et al. 2009). Pacific transient ecotype teeth suffer moderate lateral and apical wear, associated with feeding on other marine mammals (Ford et al. 2011). Generally mammal eaters show lateral wear more than apical wear (Caldwell & Brown 1964). Pacific resident ecotype and Type 2 North Atlantic teeth suffer no apical and little lateral wear (Ford et al. 2011; Foote et al. 2009). In all these papers, tooth wear is hypothesized to be due to prey type or feeding method, not to general manipulation of objects in the environment, since some populations generally suffer little to no wear and must also manipulate objects in the environment.
Almost all captive killer whales suffer moderate to severe apical wear and occasional breakage. If you follow this link, you will see several photos of captive orcas showing various levels of tooth wear and breakage: https://theorcaproject.wordpress.com/2010/09/25/the-hidden-cost-of-captivity... You can see drilled out teeth, teeth worn to the gums, and broken teeth in these photos (I have other higher resolution photos, if anyone wishes to see them). While less than a handful of juvenile to adult captive killer whales suffer no wear or breakage (such as Lolita), this is the exception rather than the rule. These photos are representative of most captive killer whale teeth. Given that captive killer whale teeth rarely or never touch the fish they are fed (thawed frozen fish are dropped directly into the open mouths of the animals and are rarely handled by the animals' teeth in any way), this begs the question of how their teeth wear or break like this. The response on SeaWorld's web page consists of two major points: 1) that moderate wear occurs when the whales' teeth "brush against" abrasive surfaces such as the walls (the suggestion is that this happens only occasionally and even inadvertently and is more than a slight touch but far less than a concentrated grinding); and 2) that "a lot" of stranded killer whales have poor dentition, which is the result of simple "manipulation" of objects in their environment. This claim does not distinguish the populations from which such stranded whales come; it simply implies that many whales from all populations have teeth similar to those of captive killer whales and for similar reasons. In short, SeaWorld's reply is saying that captive killer whale dentition is "normal." This is incorrect and I personally believe that it is incumbent upon our community to clarify for SeaWorld that this is incorrect, so the company will stop misleading the public, including the media, about this issue. Captive killer whales, as far as I understand it from what I have read and heard, break and wear their teeth because they persistently grind their teeth on the concrete walls and metal gates of their enclosures as a stereotypy. I would prefer to have a peer-reviewed reference to offer here for this claim, but unfortunately the public display facilities holding killer whales have published very little of substance on captive killer whale dentition. The only relevant paper I was able to find was in Zoo Biology (Graham & Dow 1990), describing one whale's damaged dentition and the treatment for it. This paper clarified that the teeth of this one animal were worn by "biting a cement structure in the pool." Indeed, they note that for whales in net pens, "there are no hard surfaces to chew on, so tooth wear is not evident after several years in captivity." For whatever reason, SeaWorld is misleading the public about the facts related to captive (and wild) killer whale dentition. As the leading marine mammal scientific society, I believe the Society for Marine Mammalogy should pen a letter to SeaWorld's executives, asking them to correct this misinformation, especially since it is being disseminated in an active public relations campaign purporting to "set the record straight." References: Caldwell, D.K. and Brown, D.H. 1964. Tooth wear as a correlate of described feeding behavior by the killer whale, with notes on a captive specimen. Bulletin So. Calif. Academy Science 63: 128-140 Ford, J.K.B., Ellis, G.M., Matkin, C.O., Wetklo, M.H., Barrett-Lennard, L.G., and Withler, R.E. 2011. Shark predation and tooth wear in a population of northeastern Pacific killer whales. Aquatic Biology 11: 213-224 Foote, A., Newton, J., Piertney, S.B., Willerslev, E. and Gilbert, M.T.P. 2009. Ecological, morphological and genetic divergence of sympatric North Atlantic killer whale populations. Molecular Ecology 18: 5207-5217 Graham, M.S. and Dow, P.R. 1990. Dental care for a captive killer whale (Orcinus orca). Zoo Biology 9: 325-330 ____________________________ [13_AWILogo_ONLY] NAOMI A. ROSE, PH.D. Marine Mammal Scientist ANIMAL WELFARE INSTITUTE 900 Pennsylvania Ave., SE Washington, DC 20003 naomi@awionline.org<mailto:naomi@awionline.org> T: +1 202 446 2120 ~ F: +1 202 446 2131 ~ C: +1 240 401 4269 www.awionline.org<http://www.awionline.org/> P Please consider the animals and their habitat before printing.
