MARINE MAMMALS MATTER
Whales.. They’ve got quite the rep. They’re gigantic, they sing, and who doesn’t love Free Willy?! They get a lot of love, and for very good reason.
Whales are one of very few marine mammals. Like land mammals, they give birth to live young, they nurse with milk, they’re endothermic (warm blooded) and they have hair!
All life on Earth is believed to have started in the ocean. We started as tiny creatures, grew eyeballs, tales, fins, a backbone and ventured our way onto land as a crawling, mud-dwelling ichthyostega (don’t even try to pronounce that), around 350 million years ago.
But right after developing lungs, the descendants of whales decided life on land wasn’t all it was cracked up to be. They turned around and headed back into the ocean. I assume this was due to Sebastian’s iconic ‘Under the Sea’ anthem but that is yet to be confirmed.
These indecisive creatures stayed in the ocean where they would evolve over thousands of years back into fish but with the added goodies of mammalian life.
Because they evolved from land animals with limbs under their bodies, their spine doesn’t naturally move side to side, it moves up and down. Their noses crept all the way up their faces and are now blowholes, their whopping big lungs have a capacity of 5,000 Litres and can hold breath for up to 90 minutes.
Many years ago the ocean was filled with the long, slow melody of whales but over time we have seen whale numbers gradually drop. Despite being illegal, Japan, Norway and Iceland kill around 1,500 whales every year combined.
Whales eat fish and thousands of krill in a single mouthful and it is on this basis that whalers argue that killing whales is good for humans because it boosts the food available for us to eat.
Despite these arguments, as whale numbers have decreased so have the number of krill.
How is this possible? Surely if you remove a predator, the population of its prey booms, right?
Not in the case of whales and krill.
Whales don’t just eat krill, they also help krill breed and grow, along with much of the life in the ocean.
The electric beaters of the ocean Sourced from Pixabay
Whales eat at depths of total darkness. When they need air, they rise to the surface and bring the phytoplankton with them. The surface water receives sunlight and is called the photic zone. After this free ride the phytoplankton finally have the opportunity to soak up the sunlight and photosynthesise along the ocean’s surface.
As plankton photosynthesizes, it grows and begins to sink out of the photic zone and heads back to the bottom of the ocean. But not with whales on the job. By plunging back up to the surface, whales keep phytoplankton in the photic zone, giving it more time to photosynthesize and reproduce before it sinks back into darkness.
Then, as if they hadn’t already done enough, whales release fecal plumes (poo) throughout the ocean’s surface. These are extremely rich in iron and nitrogen and fertilize the phytoplankton, fast-tracking their growth.
Plankton soaking up some rays, and fecal plume. Source: Chris Moody- Flickr
More plant plankton means more animal plankton. Animal plankton is krill and fish food, so more whales therefore mean more fish food. More fish food means larger populations of happier, fatter krill and fish!
Plant plankton also absorbs carbon dioxide from the atmosphere. Then, having absorbed the carbon, it carries it down to the bottom of the ocean, where it stays for thousands of years.
The more whales there are, the more plankton there is, and the more plankton there is, the more carbon is drawn out of the air. It is estimated that sperm whales poo helps sequester over 200,000 tons of carbon every year by fertilizing plankton.
If whale numbers continue to fall, we will lose far more than their beautiful song and graceful leaps, there would be a huge loss of life in the ocean. We should all be extremely grateful these beauties decided to head back into the ocean.