Report: Are jellyfish so dumb that their evolution needed help?
Posts labeled “Report:” will discuss material posted on other sites, particularly ones that contain silly arguments
An interesting report in this paper:
Gemmell, Brad J., Kevin T. Du Clos, Sean P. Colin, Kelly R. Sutherland and John H. Costello. 2021. The most efficient metazoan swimmer creates a ‘virtual wall’ to enhance performance. Proceedings of the Royal Society B (Biological Sciences)
argues that jellyfish use a subtle fluid dynamic effect, the ‘ground effect’, to swim efficiently. The suthors used sophisticated monitoring techniques to measure the movement of water, as well as computationally intensive calculation methods of fluid dynamics. They found that when the body of the common Moon Jelly Aurelia aurita contracts, it creates two vortices, each like a smoke ring, but rotating in opposite directions. Together they function as a ‘virtual wall’ against which water is pushed. The result is extraordinarily efficient swimming. The paper is open access and may be read at the link above.
The ground effect has been known in fluid dynamics since the 1920s, when pilots reported that their planes flew more efficiently when close to the ground, an effect due to the air beneath the wings being compressed by being squeezed between the wings and the ground. A number of countries have tested vehicles used the ground effect to “fly” just above the surface of the ocean. The most active development program was the models of “ekranoplans” produced in Soviet-era Russia in the 1970s and 1980s, one of which you will see above. The model shown there was also capable of a limited amount of actual flight.
But as astonishing as jellyfish are, and as surprising as ground-effect vehicles are, they have inspired an actual flight of fancy. This was by the ever-astonishing Denyse O’Leary, who writes for the ID advocacy blog Uncommon Descent. Her argument needs to be quoted – you would not believe me if I summarized it …
O’Leary, who writes for Uncommon Descent as “News”, is an expert at invective. A common trope of her reports is that science is wrong, a position that she backs up with frequent reports on fudged data, failures of peer review, and failure of further work to confirm initial reports. This time, for a change, she is merely implying that scientists have failed to notice a dramatic implication of some work – that the feature could not be explained by ordinary evolutionary mechanisms but must imply that there was Intelligent Design. After citing a report on jellyfish and ground effect and indicating that the original paper is open access, she simply says (here):
Either jellyfish are smarter than we think or there is design in nature.
This is astonishing – I am glad I am not a coffee drinker because I would have had to replace my computer after reading it.
There are only two comments on that post. True to the form of UD commenters, who are the ultimate ID cheering section, one from commenter Mahuna says
.... OK, clearly some INDIVIDUAL jellyfish did NOT invent this technique on a slow afternoon and then TEACH it to his bros. It is MUCH more likely, since ALL jellyfish know how to do this, that the skill was INSTALLED way back when the Designer was messing around with the pre-production prototypes. ....
while commenter Querius says “Yes, indeed!”.
Apparently ID advocates, or at least these ones, cannot understand how natural selection could favor an adaptation that makes use of a sophisticated concept of physics or engineering unless the organism understands the physics. I suppose that the fact that trees use capillary action to bring water from the roots up to the leaves must also be evidence for ID, since trees scarcely understand the relevant physics. Years ago, I saw an ID advocate argue that it was hard to explain how the colors of some birds could come from diffraction of light since birds do not understand the concept of diffraction. (I wish I had kept a link to that quote). Likewise all the adaptations of single-celled protists must be the result of Design, since protists understand so little chemistry and physics.
It’s facepalm time.
A slightly off-topic aside: The ‘flight’ of ground-effect vehicles is related to the way hovercraft move across water. I’ve experienced that myself. In 1983 I crossed the English Channel on the hovercraft ferry from Boulogne, France to Dover, England. The craft rested on pillars rising from a concrete pad which was at the top end of a smooth, sloping beach. After we boarded it on a gangway and seated ourselves in rows of airline-style seats, the engines started up. The fans that blew air down inside the skirt of the craft made it rise up a few feet, and it started to slide down the beach, just barely touching the sand. It came to the water and started out across it, driven by the propellers mounted above the craft. That was the fun part. Unfortunately the motion of the hovercraft consisted of riding up the front of a wave, and then slamming down once past it. This kicked up a lot of spray, which rose in a cloud around the craft, coating the windows so that one could not see much. It also leaked in at one place in the plexiglas canopy. The result was an uncomfortable ride, though it did get to Dover in only about an hour. At the Dover end it drove up onto the beach, riding above it as it did on the water, until it settled onto its supports there. There is still one hovercraft ferry service in England, between Southsea in Portsmouth and the Isle of Wight.