There is a lot of controversy tied to this topic. The defenders of the animals affirm that the folding of the dorsal fin is due to the unsanitary conditions of captivity and confinement itself. Meanwhile, aquarium workers affirm that it is not incompatible with life or a sign of poor he alth in killer whales.
In this article on our site we will talk about why captive killer whales have bent dorsal fins and if this occurs in wild state.
Physical characteristics of killer whales
With their black and white coloration, orcas or killer whales are one of the most easily recognizable aquatic mammals. Killer whales are a species of dolphin with a maximum body length of 9 meters in males and 7.7 meters in females. In addition, by increasing sexual dimorphism, males develop much larger fins than females, including pectoral fins, tail, anddorsal fin , which can reach 1, 8 meters in males Newborn orcas weigh approximately 200 kilograms and can measure between 2 and 2.5 meters in length. As a curious fact, a study of captive killer whales revealed that females are larger than males up to 6 years of age.
As we said, one of the most recognizable traits of killer whales is their coloration. They are normally black on the back, and white on the bellyBehind the eyes, they have white elliptical spots. At the posterior base of the dorsal fin they have a gray spot called “saddle spot”. Newborns have the areas that are usually white in adulthood orange and do not have the gray spot behind the dorsal fin during their first year of life. There are different colors between the different populations of killer whales, especially with regard to the spots on the eyes and the gray area on the back.
The dentition of killer whales is somewhat different from that of other odontocetes (suborder of cetaceans to which killer whales belong). Their teeth can reach up to 10 centimeters in length. When their mouths are closed, their upper and lower teeth overlap, resulting in a jaw that is wider than other odontocetes.
The differences that exist between the different populations, not only at the morphological level but also ecologically and ethologically, are so diverse that experts believe that the taxonomy of this group should be revised.
The fins of killer whales in the wild
According to various studies[1][2], the fins of killer whales can have several functions First of all, they help them swim better, be more hydrodynamic and faster while swimming, since they are predatory animals and they hunt for their food.
Likewise, it is speculated that they can also serve as refrigerators, as in the case of elephant ears. In moments of hunting and fleeing, the orca's body heats up, so its fins serve to move water around the body and cool it.
On the other hand, it is part of the sexual dimorphism within the species. Males have larger dorsal fins than females, they also have it straight. The females, on the other hand, have a small dorsal fin that is twisted backwards.
Why does the dorsal fin of killer whales bend?
It is not known for sure why the fins of captive killer whales fold. What is a fact is that hardly any specimens are seen in the wild with this characteristic, except for sporadic cases or what happened in New Zealand waters, where 23% of the males of one population had a collapsed dorsal fin. In this study, the condition of the fins was attributed to fighting for dominance, as it occurred together with deep scars on the back of the males.
The fact that captive killer whales have their fins folded in this way is thought to be due to a lack of deep water swimming(as they normally would in the wild). Swimming at great depth causes the pressure exerted by the mass of water to keep the internal tissues of the fin in good condition, keeping it upright.
Other potential causes may include dehydration and overheating caused by not being able to swim freely and having to be exposed to air continuously during training and exhibitions. All this coupled with a poor diet based on defrosted fish.
