What do Orcas (Killer Whales) eat? Are Orcas at top of the Ocean Food Chain?

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What do Orcas (Killer Whales) eat?

Orcas (also called Killer Whales) are the largest species of dolphins on planet earth. They are social animals and so they stay and hunt in groups of family members called pods.

They have somewhere around 48 to 52 teeth on their upper and lower jaws with each teeth being 4 inches long or so.

So, Orcas (Killer Whales) are able to feed on large mammals like seals, dolphins, moose, porpoises, sea lions; fishes like salmon, chinook, stingrays; birds like penguins, cormorants, shags, gulls; molluscs like squids, ooctopus, cuttlefish, nautilus, etc.

They are also known to feed on sea turtles; on other killer whales in rare case scenerios; and also on other whale species like grey whales, minke whales, sperm whales, etc.

They prefer hunting and feeding on small, weak, and young preys more often. It’s because hunting a huge prey like the killer whale, sperm whale, etc. demands the requirement of more hunting pod members, energy, and several hours of hunting time.

Orcas show diverse diet in regions where there’s a good availability of food. Whereas, those orcas that live in tropical areas show more generalized diets due to the lower food availability.

They use their one set of peg like teeth having cone-shaped look to firmly tear the flesh off the body of its prey.

It is also to be noted here that their teeth once lost cannot be replaced by another set.

It is also to be noted that Orcas don’t use their teeth to chew and feed on. They just use it to cut the flesh, thick skin, and break the bones and hard shells if the prey is a large animal.

However, if the prey is small as compared to the size of Orca’s mouth then they will simply swallow the prey. This can be well seen when they feed on small seals and sea lions as a whole.

They stay, roam, dive, and hunt in groups of their family members. So, it is that’s why they are also called “wolves of the sea”, because they hunt in groups like wolf packs.

Photo: Killer Whale in Shanghai, China

Why are Orcas called Killer Whales?

Due to the Orcas’ feeding habits by successfully planning, grouping, and hunting in groups by surrounding their prey like the larger whale species from all sides gave them their name as the Killer Whales.

Orcas are called Killer Whales becasue in groups they kill larger species of whales and even other orcas of the same or different species with ease.

This name was given by ancient mariners and sea sailors who watched them live in the midst of the sea while they are chasing and hunting other whales.

While hunting in groups by coming to the suface water they lead to causing massive splashes and waves emerging out of the sea water.

Some people also call them killer dolphins because of the fact that they are the largest species of dolphins on planet earth, and that they can hunt and eat other species of dolphins.

They are highly intelligent and social animals that can live and hunt in family groups of up to 40 individuals. Their group is called pod.

And, it is to be noted here that a pod with atleast 40 strong adult killer whale members are enough to plan and surround a blue whale and kill it. But, it may take time of upto 3 to 4 hours or more to succesfully kill such a big prey.

They follow a very powerful, strategically planned, and aggressive hunting pattern with proper group co-operation.

So, they prefer preying on young whales when in groups by chasing the mother to fatigueness, and then strategically separating the prey whale’s group and the mother away from the young whale to kill and prey upon it.

EXPLAINED: Orcas (Killer Whales) are at top of the Ocean Food Chain

Orcas (Killer Whales) are the apex predators and so they have no natural predators. And also due to their diverse diet they are considered at the top position of the ocean food chain.

If we see their feeding relationships within an ocean ecosystem we will find that Orcas are quaternary consumers on a five level food chain.

And so, as per the ecological trophic dynamics, they occupy the highest trophic level in their food chain.

Let’s understand this better through an example: Orcas being the apex predators feed on almost anything fleshy. That is for example, Orcas can feed on Sea Lions. Those Sea Lions do feed on various fishes like salmon, sardines, and on other marine creatures like squid and octopus. The creatures that sea lions feed on eats the small marine creatures like krills, crabs, lobsters, and crayfish. Creatures like krills, crabs, lobsters, and crayfish feed on marine plants and get the energy.

So, here in this example, we can consider marine plants as the primary producers. Krills, crabs, lobsters, and crayfish as the primary consumers. Salmon, sardines, squid, and octopus as the secondary consumers. Sea Lions as the tertiary consumers. And, the Orcas (Killer Whales) as the quaternary consumers respectively.

Orcas can feed on sea otters, other whales, sharks, various big fishes, sea birds, molluscs, amphibians, etc. that also make them appear at top of the food chain.

As they have a diverse diet, it was just an example amongst so many to show how Orcas are at the top of food chain when they feed on sea lions.

So, there’s a beneficial site for the Orcas being at the top of the food chain as apex predators.

They being at the top of the food chain keeps a natural check and maintains the species below them in the food chain. By doing this, they do also serve as an indicator for ocean health.

By being the quaternary consumers they help control the population of the various other species in the ocean ecosystem by keeping it in a balance for the proper flow of energy and nutrients from the producers to the consumers.

In doing so, Orcas also help remove the weak and the sick marine creatures, as well as keeping the balance with competitors helping to ensure species diversity.

Some of the most popular questions answered

1. Do orcas eat dolphins?

Yes, orcas do eat dolphins. Most of the Transient Orcas are known to feed on dolphins more often in the seas and oceans.

They in groups are known to chase after dolphins at an average speed of 27 mph and surround them from all sides so that the fast swimming dolphins can’t escape from the predation of killer whales.

It is to be noted that most of the orcas are the only predators of white-sided dolphins in the northern Pacific oceans off the British Columbia and Washington coasts.

2. Do orcas eat humans?

In the ocean, it is rare that Orcas will attack humans and such cases of orcas attacking humans have been rarely reported in the wild.

It’s because it’s rare for humans to encounter orcas more often as they live and hunt deep in the midst of the oceans while sometimes coming up to the surface water for a long time.

Human and orca conflict can only occur when Orcas come very close to the shore i.e. when females orcas are close to the shore with their young ones.

However, when in captivity Orcas have been known to attack humans and divers that swim close to them.

3. Do orcas eat penguins?

Yes, orcas can eat penguins if they encounter one on their way. It is when penguins occasionally go a lot deeper into the seawater chances are very high that they may be predated by Orcas.

Gerlache Killer whales with a size between 6.9 m or 22.6 feet that are found at the Gerlache Strait or de Gerlache Strait of the Antarctic Peninsula are known to prey upon Penguins very often.

However, it is also to be noted that Penguins only constitute a small portion of the wide range of living species that makes up orca diets.

4. Do orcas eat blue whales?

Blue whales are the biggest animal on planet earth, and that they have no natural predator except for the Orcas who dare to attack and hunt blue whales in large pods of at least 40 members.

Killing a blue whale is not so common for the orcas as it can demand a huge requirement of energy, many adult pod members, and several hours of battle to kill one.

So, orcas mostly choose to feed upon easy and quick diets like birds, sharks, sea lions, etc. than chasing after a huge blue whale.

And, if they choose to kill one then they may opt to attack baby or juvenile blue whales ignoring the adult ones.

So, maybe that’s why there is just a handful of times that orcas have ever been recorded killing a blue whale.

5. Do orcas eat sharks?

Yes, it is not very rare for orcas to eat sharks. Orcas have been known to attack in pods and successfully kill various shark species like the Great White Shark, Tiger Shark, Hammer Head Shark, etc.

Orcas have been observed preying on Great White Sharks all over the world. This is also one of the reasons that caused the Vulnerable (VU) status to the Great White Sharks by IUCN.

And that many of the shark species that Orcas feed on are now considered Endangered or Critically Endangered. Many of these sharks species are native to South Africa.

6. Do orcas eat seals and sea otters?

Yes, orcas also eat seals. Seals are one of the most well-known foods of the Orcas. Orcas are known to swallow small seals and sea lions whole with ease.

Yes, orcas being the apex predators are also known to feed upon sea otters as a whole. Both sharks and killer whales are the top predators of the sea otters when they come in contact with their prey.

Why do some Killer Whales only eat fish?

Orcas that live in tropical areas show more generalized diets due to lower food availability, and that they have well-adapted themselves to do so.

Those that live in regions like in the inland waters of Washington and British Columbia don’t show a diverse diet and are mostly seen to feed on fishes like salmons, sardines, herrings, mackerel, etc.

Killer Whales that eat only fishes are called Resident (fish-eating) Orcas, and they lack most of the characteristics of the wild Transient (mammal-eating) Orcas.

Resident (fish-eating) Orcas are also known to travel, socialize, and hunt in large pods of closely related individuals just like the aggressively hunting Transient (mammal-eating) Orcas.

Resident (fish-eating) Orcas can be easily seen in the Northeastern Pacific Ocean ranging from Vancouver Island’s north to Southeastern Alaska zone.

Many fish-eating killer whales can also be seen in the greater Puget Sound region of the Pacific Northwest, an inlet of the Pacific Ocean, and part of the Salish Sea.

Many fish-eating orcas can also be seen off the coasts of Russia and Japan. They highly prefer feeding on fishes like salmon and mackerel.

At present it has been reported that many of the Resident (fish-eating) Orcas are starving to death with a declined Orca population due to the decreasing population of their food species like Chinook Salmons.

This declination of the population of the food species like Chinook Salmons is due to negative impacts caused due to overfishing, hydroelectric projects, and the increasing population of the harbor seals that feed on Salmons.

So, those fish-eating orcas that inhabit the greater Puget Sound region of the Pacific Northwest are also known as the Southern Resident killer whales. They are now considered Critically Endangered (CR) and so are at an extremely high risk of extinction.

This extremely high risk of extinction of those fish-eating orcas is because they highly feed on Salmons that account for nearly 96% of their diet, including 65% of the large fatty Chinook Salmons species.

And, that the population of the species like Chinook Salmons are also highly decreasing thus leading to the decrease of the Southern Resident Killer Whales.

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