Surprises from the Ocean
News from marine biology and geology are unexpected from a long-age, evolutionary perspective.
A deep sea fish has been found to be warm-blooded, researchers from NOAA reported in Science Magazine. The opah, a large, round fish with global distribution, has systems that give its whole body—heart, muscles and brain—a higher temperature than its surroundings. Some fish, like tuna and certain sharks, are able to produce heat locally, but the opah warms itself all over, enabling its systems to work at higher performance in its frigid habitat. How does it do it?
To reduce convective heat loss, these fishes have retia mirabilia or “wonderful nets” of blood vessels that form counter-current heat exchangers composed of densely packed arterioles and venules running in opposing directions, in which warm venous blood returning from the heat-production site transfers its heat to the cold arterial blood arriving from the gills. To date, these retia in fish have only been observed in connection with specific muscle groups or organs, leaving the heart and many other tissues at ambient water temperature.
Counter-current heat exchangers (CCHE) using a rete mirabile (Latin, “miraculous web”) of blood vessels are known in whales, dolphins, seals and other marine mammals. In the fish’s case, these retia are packed in the gills, allowing the fish to transfer heat from the muscles to the cold vessels exposed to sea water. How did this evolve? The researchers had no clue:
This study presents morphological, temperature, and behavioral data that demonstrate an independent evolution of a more whole-body form of endothermy present in the opah, Lampris gutattus—a poorly studied, large, mesopelagic fish with a circumglobal distribution. We show that unlike other fishes, the opah has putative heat-conserving retia located inside the gills, thus isolating the primary site of heat loss from the rest of the body. In situ temperature measurements acquired for freshly sacrificed opah landed during fisheries surveys reveal that the entire body core (pectoral swimming musculature, viscera, and heart) and cranial region (Table 1) are all significantly warmer than the environment.
The last paragraph adds nothing to the “how” of evolution. It just says that this fish “converged” on this “innovation” independently:
In many respects, the opah has converged with regionally endothermic fishes such as tunas and lamnid sharks for increased aerobic capacity. However, unlike these active, more surface-oriented predators that are thought to be derived from tropical ancestors and to use regional endothermy to expand their thermal tolerance or habitat utilization into deep and colder waters, the opah’s evolutionary history is likely tied to greater oceanic depths, with all but the most basal lineage of the Lampridiformes inhabiting the mesopelagic zone (200 to 1000 m depth). Therefore, rather than using regional endothermy to dive below the thermocline during temporary forages, the opah (with its more whole-body form of endothermy) is distinctively specialized to exploit cold, deeper waters while maintaining elevated levels of physiological performance. The discovery of this form of endothermy, coupled with the recent finding of several distinct opah species inhabiting different regions of the world’s oceans (including the subpolar southern opah, L. immaculatus), sets the stage for future comparative studies to further explore this key evolutionary innovation.
Live Science shows a picture of the opah, but offers no solution to how its warm-bloodedness evolved. One example of CCHE with rete mirabile will be illustrated in Illustra Media’s new film, Living Waters (available this summer), as a challenge to natural selection.
Fish need to avoid sunburn, too. “Scientists from Oregon State University have discovered that fish can produce their own sunscreen,” an article in Science Daily reveals. “They have copied the method used by fish for potential use in humans.” Watch for products containing the new safe biomimetic compound gadusol:
In the study published in the journal eLife, scientists found that zebrafish are able to produce a chemical called gadusol that protects against UV radiation. They successfully reproduced the method that zebrafish use by expressing the relevant genes in yeast. The findings open the door to large-scale production of gadusol for sunscreen and as an antioxidant in pharmaceuticals.
“The fact that the compound is produced by fish, as well as by other animals including birds, makes it a safe prospect to ingest in pill form,” says Professor Taifo Mahmud, lead author of the study.
Longest Mammal Migration
The prize for longest migration of any mammal is: (the envelope, please)—the gray whale. Live Science reports that a female gray whale was tracked migrating from Russia to Mexico and back again, a round trip of 14,000 miles in 172 days. This breaks the humpback whale’s record of 10,200 miles. “My respect for navigational skills in gray whales has changed tremendously,” commented Bruce Mate, director of the Marine Mammal Institute at Oregon State University. The BBC News coverage focuses on populations of the behemoths and their endangered status.
Rewrite the Textbooks on Extinction
Evolutionists have long thought that a secondary cause of the end-Cretaceous extinction that killed the dinosaurs was ocean acidification from the asteroid impact thought to have initiated the catastrophe. A paper in PNAS pulls the rug out from that assumption:
We investigated whether ocean acidification could have caused the disappearance of the calcifying organisms. In a first detailed modelling study we simulated several possible mechanisms from impact to seawater acidification. Our results suggest that acidification was most probably not the cause of the extinctions.
The event saw the loss of 100% of ammonites and 90% of calcareous nannoplankton and foraminifera. From studies of rocks and from models, they conclude, “We find that the acidification produced by most processes is too weak to explain calcifier extinctions.” This finding could affect thinking about other mass extinctions in the old-earth evolutionary scenario.
The more data, the more evolution collapses and intelligent design shines. Convergent evolution is a theory in crisis; so many examples now, it amounts to multiple miracles. And the “miraculous webs” that keep animals warm or cool as needed contain so many interrelated systems, they cannot have evolved by slow, gradual mutational changes.
Watch for the arrival of the new Illustra film Living Waters. It’s going to be superb! Join Illustra’s Facebook page and YouTube channel to keep in touch (Twitter ID is: @illustramedia). Producing documentaries of this quality is not cheap. Consider being a supporter of Illustra with contributions and prayer. The team will be working non-stop till the end of May to pull all the elements together for the final cut, then sending it out for duplication on DVD and Blu-ray. This is a good time to hold them up in prayer. The new film, including interviews with some new experts, glorious animations, spectacular cinematography and a new musical score will easily match or surpass the excellence of the two prior entries in the “Design of Life” series, Metamorphosis and Flight. This NOVA-quality trilogy—a much needed alternative to the Darwin-saturated documentary market—will challenge Darwinian evolution and show the power of intelligent design science to the world. Here’s a link to get on their mailing list and/or make a donation.