Truth about Orcas?

Question

Is it true that Orcas that live in the wild have straight dorsal fins, and when they live in captivity they have curled ones?

If so, why is this true?!

Answer 1

i dont think thats true...

maybe its just that film 'free willy' .. he had a curled one just to make him special i think...

Answer 2

In general, yes it is. There is a number of theories on this phenomena.

The most commonly quoted is that the muscles around the fin slacken due to lack of exercise and the fin subsequently collapses.

There is also the idea that due to being forced to swim in circles (most animals swim primarily in one direction, mainlu counter clockwise due to physiology of the nasal sac system), an uneven amount of pressure is exerted on the fin and it collapses.

Another theory is that the collagen in the fin is affected by a number of factors in captivity; the animals spend an increased amount of time at the surface, exposed to the sun, softening the collagen and during the growth spurt in the early teenage years, when the fin becomes large and heavy, unlike wild orcas, the animals do not regularly dive to great depths where the fin would be kept straight by the water pressure exerted on it, allowing the collagen to harden with time.

it could also be external influences, exposure to chemicals not experienced in the wild that could have an effect on the rigidity of the collagen, after the Exxon oil spill in 1989, two animals that were known to have come in contact with the oil had completely collapsed fins within 2 years although both of these animals were also thought to be ill, so whether it was the oil that did it or their weakening condition, is not clear.

Finally to some point it is thought to be genetic, there is a population in New Zealand here something like 20% of orcas have collapsed dorsal fins but although this is commonly the explanation quoted by Seaworld to uphold the image that the animals are healthy and happy as can be, it does not hold as most of the orcas in Seaworld are descended from the British Columbian Resident population where the rate of dorsal collapses is only about 1%.

It should also be noted that complete collapses are rather less common in the wild although they do bend and partially collapse, especially in the population mentioned previously.

There have been cases where the fin drooped and later become upright again but only in short term captives, like an adult male who was held for rehabilitation in 2002, his dorsal fin showed signs of starting to collapse, though i believe it did not collapse completely, however after his release it became rigid once again.

Answer 3

Male orcas have very tall dorsal fins, while females have more curved dorsal fins.  

The dorsal fins of captive orcas tend to flop over as if they aren't stiff enough to support themselves.  It's not clear if this is a result of injury, dietary deficiency, or some other, unknown, cause.  These floppy dorsal fins are, very rarely, observed in the wild as well.

Answer 4

yes thats true, though the reason is a mystery, no one knows why it is that their dorsal fin curls in captivity, but be assured that it does, a more interesting question would be, could an orca raised in captivity and then released have its dorsal fin resume a vertical shape?

Answer 5

It is true, that the majority of orca whales held in captivity have flopped dorsal fins. This mostly means the males though, as their dorsal fin can grow up to six feet. HOWEVER, it should not be believed as a stereotype to captivity, because there have been documented cases of flopped dorsal fins in the wild too.

The most reasonable explanation? Gravity.

Dorsal fins on whales have no bone (look at the skeleton); they are made of cartilage, like our nose and ears. Feel how much more flexible your nose and ears are than say, your fingers when stiff.

So, this means that the dorsal fin needs to be supported, in order for it to be straight. As wild orcas are in the deep ocean water, submerged often, the fins are held up by the water. But in captivity, the orcas spend more time at the surface, whether it be recieving their food, or performing their behaviours for the crowd. Tanks at aquariums aren't deep enough anyways, for an orca to be completely submerged for a comfortable amount of time.

Of course, that is only a theory, but one that most scientists point toward.

Another possibility is that as the whale reaches maturity (much like our human puberty) their dorsal fin cartilage is at its most flexible state, for it'll be experiencing a big growth. So, because in captivity the whale is performing in quick movements nearly 5x the amount of a wild orca, they're dorsal fin will be shaken, wobbled, and banged. It's not that much more differant than the first theory.

A handful of orcas in captivity have straight dorsal fins, but all of them are female. No male over the age of seven in captivity has a straight dorsal fin.

Answer 6

this is very true!

Orca's kept in captivity have a much smaller living space than those free to roam the open sea.  They can't dive to the depths required, and cant exercise as much as they should.

The curled dorsal fin could be a result of them not having the space to grow properly, or it could be a result of depression felt from living in inadequate pools.

It's a known fact goldfish will only grow to a size that suits the bowl they are placed in...maybe this is natures way of showing the Orca's shouldn't be kept in tanks in aquarium parks!