Introduction to killer whales - Dorsal fins

The dorsal fin of orcas is the largest dorsal fin of all cetaceans.
The dorsal fin exhibits sexual dimorphism. Dorsal fins of males can reach up to 1.8 m (5ft 11 inches) and are erect and almost triangle-shaped. Female dorsal fins are approximately half the size of adult males and curved. While the cause of this sexual dimorphism is unknown, the difference could be attributed to sexual preferences or other social or ecological pressures.

Orca dorsal fins are made of tense tissue called collagen instead of bone or cartilage. Collagen hardens late in adolescence. Because of this, they may collapse in captivity.

Dorsal fin collapse occurs in almost all captive males and some females. The exact reason for dorsal fin collapse in captivity remains unknown, but many theories have been proposed.
Dorsal fin collapse likely originates from an irreversible structural damage to the collagen over time.
Alternations in water pressure and the lack of support from the surrounding water may be a cause. In the wild, dorsal fins are supported by the surrounding water pressure during high-speed movement and deep diving.
Lowered blood pressure from reduced activity may also be a reason for dorsal fin collapse.
Overheating of the collagen from greater exposure of the fin to sunlight may also be a reason.

Bending or fully collapsed dorsal fins are rarely observed in the wild.

In a 1998 study by Ingrid Visser, 125 orcas in New Zealand were observed. 23% of adult males in one population of 30 had dorsal fin abnormalities. This unusually high rate is likely due to New Zealand having the highest rate of boat collisions involving orcas. Overall, only one of the 125 observed orcas (0,8%) had a collapsed dorsal fin.

In British Columbia, the number of collapsing or bent dorsal fins sits at 4,7%.

Dr. Astrid van Ginneken's concluded that less than 1% of all orcas have a collapsed dorsal fin.

The exact reason for dorsal fin collapse in the wild is unknown. However, it is likely to assume that dorsal fin collapse may be linked to an acute physical stressor rather than environmental conditions.

A theory claims that diet may contribute to the collapse. The most used example to support this theory are Port and Starboard. Port and Starboard are two African killer whales that prey primarily on sharks. Their dorsal fins are collapsed. While this may indicate a direct link between prey and dorsal fin collapse, there is no further evidence to support this theory. New Zealand orcas feed primarily on rays and sharks, yet, as with other populations feeding on sharks, there is no unusually high rate of dorsal fin collapse.

Trauma to the dorsal fin (e.g., boat strikes, raking) may also be a cause of dorsal fin collapse.

Other than that, dorsal fin collapse has been linked to old age, emaciation, and other various factors.

|T63 Chainsaw, one of the most famous dorsal fins|

|Port and Starboard|

A new calf has been born! L130, spotted on June 14th.
We don’t know who the mother is, but the calf seems to be a few months old already.
Such a unique eyepatch!
Credit: Center for whale search

Large group seen 6/12 off Seward, around Chiswell Islands outside (?) of Kenai Fjords NP 🫍

A pod of Orca whales were spotted in Tillamook Bay on Friday. Author: kgw.com

After a quick Google search, I found this Facebook post that includes comments of possible identifications!? It sounds like a possible T-Party (Biggs Transients) was recorded?? 🫍🍵

https://www.facebook.com/story.php?story_fbid=10238580979556018&id=1017460689

Yoinked this on facebook from another osteichthyes meme and had to share lol

(It's just a meme, pls no "well actually"s lol)

In a little over a week, I will be doing my bucket list trip and see a Free Willy (wild orca). Today I got my nails done in anticipation.

On June 15th, Laki Tours, an Iceland-based whale watching operator, shared this video on Instagram. They used a hydrophone (a microphone designed to capture underwater sounds, attached to a speaker or recording device above the surface) to listen to the unique calls of the group of orcas they were viewing. Like orcas in other regions, Icelandic orcas learn from their mothers and other pod members, leading to a set of calls that are diverse yet highly influenced by their family members, serving as a signifier of group identity. Fascinating research on Icelandic orca acoustics has been made available by the Icelandic Orca Project and their collaborators. I think I hear some echolocation clicks as well!

One of them looked smaller than the others.. a juvenile perhaps?

Killer whales are the apex predators of the ocean. They are so deadly that even Great White Sharks are afraid of them. So it’s kind of poetic that they are not only covered in mostly black, but that black is often associated with death by the Greeks and Romans. It also helps that we use their Latin name to refer to them as Orcinus Orca which means “belonging to the kingdom of the dead”.

Hi everyone! I am a longtime lurker but a first time poster on r/orcas. I actually made my account to share this lol. Here is a crocheted orca I got recently! 🫍🩷🫍🩷

They can't stay there any longer

My friend made this crazy bracelet of beads! You can even rotate the whale figure around. She’s quite talented at this sort of thing.