Copepods: the Right whale’s favorite tiny snack

Did you know that animals about the size of a granule of salt sustain one of the largest mammals on Earth? Copepods are a species of crustacean zooplankton, distantly related to crabs and shrimp. They are a favorite food of countless marine species including, perhaps most shockingly, North Atlantic Right whales – one of the largest animals in Earth’s oceans. 

At birth, Right whale calves are already 14 feet in length and by adulthood, they grow up to the size of a school bus. While you may think it is impossible that these gentle giants can grow so large eating such tiny creatures, copepods actually make up a huge part of their diet. In this article, get to know these little guys and their significance to the Right whale.

So what are Copepods anyways?

Copepods are a type of aquatic crustacean zooplankton that are just 1-2 mm in length. They feed on phytoplankton, making them a key link in the marine food chain: phytoplankton convert energy from the sun into food, are eaten by copepods, who then in turn feed countless marine species. 

Copepods can be found all around the world – their habitats range widely and vary by salinity, temperature, and altitude. This could include a freshwater stream on a mountain peak, a deep ocean trench, a hydrothermal vent, or even a wet leaf in your backyard. In short, if there’s water, there could be copepods. 

How do Right whales survive off of Copepods?

Right whales consume copepods by filter feeding. To filter feed, Right whales swim with their mouths open, straining water through their angled baleen plates and filtering out food sources for them to consume.

It might seem hard to understand how Right whales survive off of such tiny creatures, but these little zooplanktons are actually quite nutritious and, most importantly, abundant. Copepods tend to be high in protein, making them a mighty snack for the Right whales. Additionally, they often form large blooms that are visible in the water. 

Copepod blooms form when populations of phytoplankton boom, creating an abundance of food for the tiny crustaceans. The resulting dense aggregation of copepods turns the ocean water cloudy.

The masses of copepods make it easier for the Right whales to filter-feed off of these little guys – which is helpful since Right whales usually consume up to 2000 pounds of these crustaceans every day to sustain themselves! 

Copepods are important to more than just Right whales

But Right whales aren’t the only animal chowing down on these tiny crustaceans: they are eaten by a wide variety of marine life, from fish to snails. This is what makes them so critical to the marine food web: the animals that eat copepods are often themselves critical prey for other sea life. For example, anchovies that consume Copepods may be eaten by tuna which may be eaten by sharks. In this way, Copepods have a heavy influence on marine life. 

Besides serving as the base of many marine food webs, copepods are also important to scientific research on marine ecosystems and human health. For example, tracking Copepod species richness over time can help us evaluate the effects of climate change on biodiversity. Additionally, copepods could impact human health by potentially controlling malaria through their consumption of mosquito larvae both on land and at sea. 

Climate change can affect Copepods and the animals that feed on them

As global temperatures rise due to climate change, marine ecosystems could be heavily disrupted. Scientists are still trying to understand the ecological factors that lead to blooms of Copepods so they can better predict how these ecosystems will be impacted by warming oceans. It’s not clear if warmer temperatures will hurt copepod populations – but scientists suspect that even a regional decline of copepods along the Atlantic coast could have a big impact on the 360 remaining Right whales. 

While we don’t know what climate change means for copepods, we do know that climate change is shifting the distribution and population structure of phytoplankton. We can expect that this means that copepod populations, and consequently the migration patterns and feeding habitats of animals like Right whales, will also shift, likely in some unpredictable ways. 

For Right whales, these shifting migrations patterns has meant that policies put in place to protect them no longer work as they should. The current slow speed zones for boats, critical to keeping these endangered whales from dying from boat strikes, are now out of date. That’s why we’re calling on the Biden administration to update their boat speed rules to cover more of the habitat Right whales migrate through, to better reflect the whales’ changing migration patterns. 

As ocean waters warm, we will need to adjust our rules and plans designed to protect ocean life to accommodate our new understanding of copepods and the rest of the marine food web, so we can stand up for the animals we can see–and the ones we can’t.