Fish

• Salem Media Group, Inc. (OTCQX: SALM) announced today that Beth Bacall has joined the Salem Music Network (“SMN”) based in Nashville, TN.
• The Beth Bacall Show content is available for stations to air in any daypart by ftp download.
• She has won the Christian Music Broadcaster’s (“CMB”) Industry Achievement Award for outstanding and long-term contributions to the growth of Christian music radio.
• Salem Music Network’s FTP talent includes: The Kevin and Taylor Show, Keep the Faith with Penny, The Scott and Sam Show, and The Beth Bacall Show.

• We showed that something similar may be happening in groups of fish that sense their environment using electrical pulses.
• Scientists have long known that electric fish sense changes in the electric fields they project into their waterscapes, much like the acoustic signals that bats and dolphins deploy.
• The fish rely on specialized organs in their skin that emit and sense electric fields to communicate.
• They analyzed whether individual electric fish were better at detecting objects by tapping into signals emitted by nearby fish.

• We know many species can live at much colder or warmer temperatures than humans.
• This means biological processes increase in line with temperature, reach a maximum, and then rapidly decline when it gets too hot.
• When the number of species was plotted against the average annual temperature, there was a decline above 20°C.
• Read more:
  Remote Pacific coral reef shows at least some ability to cope with ocean warming – new study

Biological processes and biodiversity

• Research in Tasmania modelled the growth rates of microbes and multi-cellular organisms and found the most stable temperature for their biological processes was also 20°C.
• This “Corkrey model” built on other studies showing 20°C was the most stable temperature for biological molecules.

marine and freshwater species’ tolerance of low oxygen
marine pelagic (open water living) and benthic (seabed living) algal productivity and fish predation rates on bait
global species richness in pelagic fishes, plankton, benthic invertebrates and fossil molluscs
and genetic diversity.
There were also increased extinctions in the fossil record when temperatures exceeded 20°C.

Increased species richness

• While many species have evolved to live at warmer and colder temperatures, most species live at 20°C.
• As species evolve to live at temperatures above and below 20°C, their thermal niche gets wider.
• In turn, this should maximise species richness across all domains of life, from bacteria to the multi-cellular plants and animals.

Predicting the effects of climate change

• This means the many marine species that can adapt to global warming by shifting their geographic distribution are unlikely to go extinct due to climate change.
• Despite the complexity of multi-cellular species, it is remarkable that the cellular-level temperature efficiencies are reflected in those other aspects of biodiversity.
• Exactly why 20°C is pivotal and energy-efficient for cellular processes may be due to the molecular properties of water associated with cells.

Mark John Costello received funding from the Royal Society of New Zealand-Te Apārangi that contributed to this research.. Ross Corkrey does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.

• More than 380 million years ago, a sleek, air-breathing predatory fish patrolled the rivers of central Australia.
• Known from at least 17 fossil specimens, Harajicadectes is the first reasonably complete bony fish found from Devonian rocks in central Australia.

Meet the biter

• This group had strongly built paired fins and usually only a single pair of external nostrils.
• Tetrapodomorph fish from the Devonian period (359–419 million years ago) have long been of great interest to science.
• They include the forerunners of modern tetrapods – animals with backbones and limbs such as amphibians, reptiles, birds and mammals.

A long road to discovery

• Packed within red sandstone blocks on a remote hilltop were hundreds of fossil fishes.
• The vast majority of them were small Bothriolepis – a type of widespread prehistoric fish known as a placoderm, covered in box-like armour.
• These included a lungfish known as Harajicadipterus youngi, named in honour of Gavin Young and his years of work on material from Harajica.

• There were early attempts at figuring out the species, but this proved troublesome.
• Then, our Flinders University expedition to the site in 2016 yielded the first almost complete fossil of this animal.

A strange apex predator

• Likely the top predator of those ancient rivers, its big mouth was lined with closely-packed sharp teeth alongside larger, widely spaced triangular fangs.
• It seems to have combined anatomical traits from different tetrapodomorph lineages via convergent evolution (when different creatures evolve similar features independently).

• Similar giant spiracles also appear in Gogonasus, a marine tetrapodomorph from the famous Late Devonian Gogo Formation of Western Australia.
• They are also seen in the unrelated Pickeringius, an early ray-finned fish that was also at Gogo.

The earliest air-breathers?

Other Devonian animals that sported such spiracles were the famous elpistostegalians – freshwater tetrapodomorphs from the Northern Hemisphere such as Elpistostege and Tiktaalik. These animals were extremely close to the ancestry of limbed vertebrates. So, enlarged spiracles seem to have arisen independently in at least four separate lineages of Devonian fishes.

• The only living fishes with similar structures are bichirs, African ray-finned fishes that live in shallow floodplains and estuaries.
• It was recently confirmed they draw surface air through their spiracles to aid survival in oxygen-poor waters.

Brian Choo receives funding from the Australian Research Council and is employed by Flinders University. Alice Clement receives funding from the Australian Research Council and is employed by Flinders University. John Long receives funding from The Australian Research Council.