I remember watching a documentary once and learned that whales need to eat tonnes (literally) of krill per day to survive. I don’t understand why this is better than eating small amounts of large fishes instead.
In: 298
A) not all whales. Toothed whales eat things like squid.
B) because swimming forward through a cloud of krill with your mouth open is way easier than chasing down and killing something bigger.
Different animals eat different things.
Orcas hunt large fish, including some sharks, and various other animals. To do that you need to find your prey, you need to be fast, intelligent, and hunt in groups.
Blue whales eat krill. They just need to open their mouth and keep swimming. Much easier.
Its the way Nature works. Krill are small and plentiful, and scoooping them up on the move is a benefit to a long distance travelling Whale. I read an article recently where the Author reckoned that the Whale population was once in the Millions, and vast amounts of Krill kept global CO2 emissions down by their life pattern eating algae and small organisms. Sharks clean up and scavenge, so everything is a part of the Food Chain somewhere.
Nature is a pyramid scheme. There is much more mass of small fish then large fish, so finding and eating many small fish is easier to accomplish than finding and eating an equivalent of large fish. Sperm whales are a type that hunt large prey in deep waters, so they cornered that market and other whales would have to directly compete with them for a limited food source. So it makes sense only a few go for large things.
Some whales do eat larger prey. You are thinking of baleen whales like the blue whale which eats krill, but sperm whales eat big things like squid and fish. They evolved to fill different ecological niches and so their physiology is adapted differently depending on what they eat.
The reason is simply to consume a lot of krill the whale just has to open his mouth. No energy on pursue etc, at least not that much.
The biggest whales are that large BECAUSE they eat krill or other smaller food sources.
The abundant nutrients krill provides allowed the evolutionary ancestors of large species like the blue whale to grow larger.
It is such a good source of food that whales are now the largest animals that have ever lived on the Earth (or at least that we know about!).
Filter feeding whales are the largest animals that have ever lived on this planet. The blue whale is THE largest animal that has ever lived, it dwarfs something like a brontosaurus by weight. Your question answers itself in a way. The reason that filter feeders eat tons of krill is that this is the most efficient method of feeding. Krill exist in a big cloud and they can’t get away from a lunging whale fast enough.
The quantity and sustainability of the food source matters of course. There is another reason however, the size of a whale’s throat is quite small relative to its size. A whale cannot swallow a human believe it or not. So they would need a very large number of “stream sized” fish. These quantities are simply not available where whales live.
Same reason your car doesn’t run on rocket fuel.
I think you’re trying to imply that because something sounds easier, evolutionarily it should be chosen? Or why God created whales that way? Either way, it’s leading the question and borderline against ELI5 rules.
They eat small fish because that’s what their body can do. Why doesn’t a lion just bite into a tree? Less energy chasing it!
Latest Answers