Plastic debris is now a bigger risk to filter feeding whales than OIL as it clogs up their hair-like baleen

  • The hair-like tissue in their jaws is better at trapping microplastics than oil
  • Which means it is more likely to get clogged by excess plastics in the ocean 
  • This could severely disrupt their feeding systems and damage their health 
  • And suggest plastic pollution is potentially more dangerous than oil spills  

Baleen whales feed by trapping food in their hair-like mouth filters and microplastic pollution now poses a greater threat to them than oil spill, researchers have found.  

The large mouths of baleen whales filter water and extract small creatures such as krill and plankton.

The mammals have evolved ways of getting rid of the oil but the recent plastic epidemic poses a new problem, and one that they are ill-adapted for. 

Microplastics are more likely to clog up the baleen filter than grease, they found. 

This means that, despite the horrific implications on marine wildlife of oil, plastic pollution may be more damaging to the long-term health of the marine giants. 

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Researchers found the mouths of baleen whales were much more efficient at capturing tiny plastic than oil due to a hair like material (pictured) in their mouths (stock)

Baleen whales, also known as mysticetes, feed by filtering food using the hair-like material inside their mouth which exists instead of teeth.  

The presence of this unique oral tissue ensures they only feed on small creatures of a certain size, like plankton and crustaceans. 

But damage to the baleen, made of keratin, is a concern to conservationists as it decrease filtering efficiency and could have a potentially harmful impact on the animal’s health. 

Whether microplastics can damage this unique filtering system has been the subject of intense speculation by scientists but opportunities to test it have been limited. 

Researchers from Hampden-Sydney College in the US led the study and wrote in the report on the topic: ‘Ingestion of microplastics may pose a greater risk to whales than ingestion of oil.  

‘We found that the baleen filter is highly effective in trapping and accumulating small plastic particles, such that plastic is both more likely to clog the baleen filter and also perhaps more likely to be ingested by whales than oil.’ 

Baleen whales, also known as mysticetes, feed by filtering food using a hair-like material inside their mouth called ‘baleen’ (show above) which exists instead of teeth


Baleen whales mostly eat small creatures such as zooplankton and small fishes, which they come across in large swarms in the ocean. 

All baleen whales have baleen instead of teeth which they use to collect shrimp-like krill, plankton and small fish from the sea. 

These bristly baleen plates filter, sift, sieve or trap the whales’ favourite prey from seawater inside their mouths. 

Baleen is made out of keratin, the same protein that makes up our fingernails and hair. 

The baleen of the bowhead whale can be be 13 inches (four metres) long. 

Baleen whales including the humpback, minke, fin and blue whales

They have clearly visible throat grooves which allow their mouths and throats to expand and balloon out as they gulp mouthfuls of seawater and food.

The research team studied baleen samples from four large whale species that feed in this way and were investigating the impact of oil and compared this to microplastic damage.  

They tested oils of different weights and thicknesses, including six petroleum-based oils and two fish or plankton oils from common prey of the whales.

On contact, excess oil can also irritate their skin, eyes and mucous membranes of whales, making them more prone to infection. 

When ingested, large quantities can inflames or damages their gastrointestinal tract, respiratory system and internal organs. 

They found that rather than sticking to oil, like human skin, baleen repelled the oily matter just as it repelled water. 

In the report of the study, the researchers wrote: ‘Baleen did not adsorb oil; oil was readily rinsed from baleen by flowing water,’ wrote the authors. 

‘Oil does not change the strength or flexibility of baleen or affects its ability to capture tiny particles. 

Although oil ingestion is a risk for whales, it does not clog their mouth filter. 

However, the researchers note that while the oil was not efficient at damaging baleen tissue, ingestion too much oil as a result of higher levels in the ocean still poses a major threat to the mammals. 

The full report is published in the journal Royal Society Open Science.

Damage to the baleen, made of keratin which is also found in hair and nails, is a concern to conservationists.The main image shows a whales swim through an oil slick and the contents of the whale’s stomach from ingesting oil (inset)

But researchers found that plastic pollution in the ocean are potentially much more damaging to the mammals’ health than oil spills. The image shows a baleen whale and the baleen filter in its mouth (stock)

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