Why does an orca have a curved fin

Despite its size, the dorsal fin is not supported by bone but consists of a fibrous connective tissue made of collagen, a structural protein. Swimming at speed, in straight lines, and in deep water provides pressure to the fin, encouraging the fin to remain healthy and straight.

In wild orcas, multiple factors such as emaciation, stress, old age, dehydration, exposure to oil spills, and injury caused by altercations with conspecifics or entanglement can lead to a loss of structural integrity in the fin, which can cause it to partially or completely collapse. Although dorsal fin collapse is not unique to captivity, it is far more common in confinement.

In the wild, the condition varies from population to population. Barrett-Lennard has speculated that this total collapse is due to an injury Barrett-Lennard In the SeaWorld video where Dr.

Instead, females and a four-year-old male are shown, who only have partially collapsing dorsal fins see Figure 2. However, Figure 3 shows a captive adult male orca with a typical totally collapsed fin , held at SeaWorld, compared to the straight dorsal fin of a free-ranging adult male orca.

Figure 2. Bottom left - Kayla, female , 26 years old ; middle left — Katina female , approximately 39 years old ; top right — presumed to be Makaio male , 4 years old — dorsal fin not visible and bottom right — presumed to be Nalani female , 8 years old.

Note partially collapsing dorsal fins, all leaning in the same direction, on all three females in this picture no adult males are shown, but please see Figure 3. Figure 3. Such collapse has been clearly associated with ill-health in wild orcas. This is Tilikum, held at SeaWorld Orlando, who has killed three humans. This adult male was photographed in New Zealand waters.

In the southern resident population of orcas there are three documented cases of drooping or complete dorsal fin collapse in adult males catalogue numbers: L42, K17, J3 and soon after this LSI was recorded, all three orcas died. Of note is that those fins are still predominantly upright and have remained so for years see Figure 4. Of those seven, only one adult male known as Slater, catalogue NZ had a totally collapsed fin. He was only ever observed the one time with the collapsed fin and was not observed again, so is considered to have died.

Animal-rights activists say that these fins collapse because the conditions under which killer whales — or orcas — are held in captivity are not healthy. Others, such as water parks that keep killer whales in captivity and use them in theme-park shows, argue that there are no health threats to killer whales held in captivity and that dorsal fin collapse is natural.

All killer whales have a dorsal fin on their back, but the male's dorsal fin is much taller than a female's and can grow up to 6 feet tall. According to research published by the U.

Scientists are not certain why orcas have dorsal fins or what purpose the appendages serve. But, there is some speculation. Whales Online says that the large dorsal fin enhances the hydrodynamics of killer whales:.

Orca Live agrees that the fins help regulate a killer whale's body temperature:. Though there are different theories about their specific purpose, it's a fact that dorsal fin collapse is far more prevalent in whales that are held in captivity. A wild orca often travels hundreds of miles in a straight line in one day. One theory as to why dorsal fins collapse in captivity is because the orca spends much of its time at the water surface and doesn't swim very far.

This means that the fin tissue gets less support than it would if the orca were in the wild, and it starts to fall over. The whales also often swim in a repetitive circular pattern.

Other potential causes for fin collapse may be dehydration and overheating of fin tissue due to warmer water and air temperatures, stress due to captivity or changes in diet, reduced activity that causes low blood pressure, or age.

He is one of the most easily identified northern residents due to his flopped over fin, which rests along his back to the left. See a video of this matriline shot near Ketchikan, Alaska this year here. As a juvenile, his fin, like all juvenile males and females, would have been small and curved. As killer whales mature, however, males and females show sexual dimorphism males and females look different. It takes until their late teens to reach the full height, sometimes reaching 1.

Females always retain and smaller, more curved fin. There is no bone inside.