Yeah I’m not sure why they picked these animals specifically. Seems like there would be some interesting data for big creatures (hippos, rhinos, elephants, whales), or unusually slow ones (tortoises, sloths).
Nothing on this chart surprises me, with the exception of salmon but that’s purely because I don’t really have any preconceptions about how efficient swimming is, beyond it feeling harder than walking in a human form.
Salmon is also a weird one to pick given their breeding method, you’d expect them to perhaps have some unusual adaptations as result of needing to swim hard upstream from time to time.
I was a bit surprised about the efficiency of swimming as well. Obviously, water has much higher viscosity than air. But, on the other side, pretty much 100% of the muscle movement can be translated into forward movement and no need to expend energy moving up and down against gravity. Also, a fish can glide a bit, unlike a walking animal (less than a bird, obviously).
Also the fastest fish (sailfish) is similar to the fastest land animal (cheetah) at somewhere around 110kmh.
Why have they animated the chart? It adds nothing, as far as I can tell.
Why all the tiny points? Is each one a data point (seems unlikely)?
Why is there only one swimmer?
Why is there a walker/runner area to the left and below swimmers? What is in that area?
Is this article just shilling for Big Velomobile? ;0)