Photograph of orcas taken by Jérémy Gonçalves.
This blog is going to be a little bit different. We are going to start a little series of blogs about orcas! So welcome to our first one. This will be a more general introduction to this fascinating species. In the future ones, we will explore topics such as their ecotypes or hunting techniques and of course, focus on our local ones here in Iceland!
Orcinus Orca is scientific name for Orca in Latin, meaning “of the kingdom of the dead”. They have nicknames, such as killer whale or wolf of the sea. The name killer whale was given to them by ancient sailors who witnessed them hunting and feeding on other whale species. However, what many people don’t know, is that the actual name was whale killer. Over time the name just got twisted into killer whale.
Physical Appearance
Orcas are famously black and white. These colours serve a special purpose. It is camouflage! When they´re swimming above prey, all the prey will see is the sun shining through the water, not seeing the white bellies of the orca. If the orca is swimming underneath the prey, all the prey will see is the darkness of the abyss instead of the black back of the killer whale. The white eyepatch, which a lot of people mistake for their eye, serves also exactly this purpose. Not only do humans mistake the eyepatches for the eyes, but also the orca's prey. So instead of attacking the actual eye when defending themselves, they only attack the eyepatch. It also serves another purpose, which is similar to why lions have this very light fur coloration underneath their eyes. It reflects light to their eyes, so they can see even better than they already do.
Male killer whales can live to around 50-60 years old and females 80-90 years old, if they are living in the wild, where they belong. Females can give birth every 3-6 years and their gestation period is 18 months. The calf will stay with the mother at least 3 years, with the first year of that being the nursing period.
The males can grow up to 10 m in length and their dorsal fins can reach a height of 2 m; whilst the females can grow up to 8.5 m with smaller dorsal fins. The males can weigh up to 11 tons and the females up to 7.5 tons. In order to lift this massive weight out of the water to breach, they need at least a speed of up to 37 km/h, which is not a problem, since they can reach speeds of up to 55-60 km/h.
A southern resident orca breaching. Photograph taken by Dave Ellifrit at Centre for Whale Research.
Behaviour
As just mentioned, orcas can breach! They will breach for similar reasons to humpbacks as investigated in this blog. We never know for certain why they are doing it, but theories include communication, happiness or feeding. Breaching has even been witnessed after successful hunts, perhaps they are celebrating the good meal. When related pods meet, breaching is also more likely. This could be due to aggression or males showing off their strength and size or be part of courting.
Other behaviours orcas display are porpoising and spyhopping. Porpoising is a leap out of the water as part of a high-speed swim. Porpoising is a great method to cover lots of sea quickly. Orcas have been recorded to travel over 160km in one day! Spyhopping, on the other hand, is when they vertically lift their head out of the water. Orcas have really good eyesight, both under and above water. So, it could be observing its surroundings, looking for other members of the pod or seeing if there’s food around.
Orcas spyhopping in Norway. Photograph taken by Julie Guiderdoni.
Of course, “the wolves of the sea” still must sleep. When sleeping, they will display a behaviour known as logging. They stay close together at the surface and take short, shallow dives. They´re cognitive breathers, which means they must think about when to breathe, otherwise they would drown. Also, they must stay alert and look out for danger. The solution to this problem is called “unihemispheric sleep”. That means that one part of their brain is asleep, while the other half is awake. Let’s say the right side of the brain is asleep, then the left eye is usually closed and vice versa. Orcas sleep for about 2-6 hours per day (it doesn´t matter if it´s day or night). At most, they will hold their breath for 17 minutes, so when sleeping this massively reduces.
Interestingly, the deepest ever recorded dive for an orca, was performed by a female, 1087m! This is significantly deeper than they would ordinarily dive.
Echolocation
The wolves of the sea also have different hunting techniques, depending on the ecotype, the population and the source of food but we will go into detail in a separate blog about that topic. But what they all have in common is the echolocation, with which they find their prey.
They produce echolocation signals by forcing pressurized air through the phonic lips. A set of two tissue complexes in the nasal passage just below the blowhole. It is possible to operate each set of lips independently, allowing the animal to produce two different signals at the same time. The sound signal is then aimed forward through the forehead, which is full of connective tissues and the bulbous, lipid filled melon. Air-filled sacs behind the phonic lips direct the sound and the melon focuses the beam as it is transferred into the surrounding water. Once the echo/sound vibration comes back, they hear it through their jaws. The lower jaw is hollow and filled with fat. Sound waves are transferred through this fat-filled cavity and pass directly into the fluid of the inner ear. Depending on the speed and intensity with which these signals are coming back, they know the distance, speed, shape, texture and composition of the objects and their surroundings.
Graphic displaying the process of echolocation taken by Southern Resident Orca Recovery.
Matrilines
Orcas live in so called “matrilines”. A matriline is an immediate family (the mother and her offspring). Multiple matrilines together (for example, you and your siblings, plus all your kids) build a larger “pod”. They have a strong family bond which can´t be broken! Their limbic system, the part of the brain that processes emotions, is more developed and advanced than that of humans. They all stay together. Since they have this strong emotional bond, sometimes when the mother passes away, the sons die as well because of grief. Usually in the animal kingdom, the sons are the ones that eventually leave the groups, once they´re old enough, so it is very interesting they stay with the mothers.
The head of the matriline is always the oldest female. She is the keeper of knowledge about hunting techniques, hunting grounds, their highly complex language, social behaviour in the pod, traditions and so many more things. This knowledge is passed on through generations.
Picture of a 3 orcas seen on an Elding tour in April 2019! Photograph taken by Sabrina Voswinkel.
This brings our first orca blog to an end. Hopefully it was a great introduction to this fascinating toothed whale. We can't wait to share the rest of the series with you!
Kylie Veal
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