How giant prehistoric fish Titanichthys fed


This 30 December 2018 video says about itself:

Titanichthys is a genus of giant, aberrant marine placoderm from shallow seas of the Late Devonian of Morocco, Eastern North America, and possibly Europe. Many individuals of the species approached Dunkleosteus in size and build.

Unlike its relative, however, the various species of Titanichys had small, ineffective-looking mouth-plates that lacked a sharp cutting edge. It is assumed that Titanichthys was a filter feeder that used its capacious mouth to swallow or inhale schools of small, anchovy-like fish, or possibly krill-like zooplankton, and that the mouth-plates retained the prey while allowing the water to escape as it closed its mouth

From the University of Bristol in England:

Ancient giant armored fish fed in a similar way to basking sharks

May 19, 2020

Scientists from the University of Bristol and the University of Zurich have shown that the Titanichthys — a giant armoured fish that lived in the seas and oceans of the late Devonian period 380-million-years ago — fed in a similar manner to modern-day basking sharks.

Titanichthys has long been known as one of the largest animals of the Devonian — its exact size is difficult to determine, but it likely exceeded five metres in length; like in the basking shark, its lower jaw reached lengths exceeding one metre. However, unlike its similarly giant contemporary Dunkleosteus, there is no previous evidence of how Titanichthys fed.

Where the lower jaw of Dunkleosteus and many of its relatives had clear fangs and crushing plates, the lower jaw of Titanichthys is narrow and lacking any dentition or sharp edges suitable for cutting.

Consequently, Titanichthys has been presumed to have been a suspension-feeder, feeding on minute plankton by swimming slowly with the mouth opened widely through water to capture high concentrations of plankton — a technique called continuous ram feeding.

However, this has remained uncertain, as no fossilised evidence of suspension-feeding structures such as elongate projections that cover the gills in modern suspension-feeding fish has ever been found.

Instead, the team sought to investigate the question indirectly, using biomechanical analysis to compare the lower jaw of Titanichthys with those of other species. Their findings are reported today in the journal Royal Society Open Science.

Lead author Sam Coatham carried out the research while studying for his masters in palaeobiology at the University of Bristol’s School of Earth Sciences.

He said: “We have found that Titanichthys was very likely to have been a suspension-feeder, showing that its lower jaw was considerably less mechanically robust than those of other placoderm species that fed on large or hard-shelled prey.

“Consequently, those feeding strategies (common amongst its relatives) would probably have not been available for Titanichthys.”

The fossils of Titanichthys used in the study were found in the Moroccan part of the Sahara Desert by co-author Christian Klug, a researcher at the University of Zurich. He added: “When you do fieldwork in the Anti-Atlas, massive skull bones of placoderms can be found quite frequently.”

The team tested the resilience of the jaws by virtually applying forces to the jaws, using a technique called Finite Element Analysis (FEA) to assess how likely each jaw was to break or bend.

This revealed that the lower jaw of Titanichthys was much less resistant to stress and was more likely to break than those of the other placoderm species, such as the famous Dunkleosteus. Therefore, the jaw of Titanichthys probably would not have been able to withstand the higher stresses associated with their strategies of feeding on large prey, which thus exert more mechanical stress on the jaws.

This pattern was consistent in both sharks and whales, with the suspension-feeder proving less resistant to stress than the other species within the same lineage. Further analyses comparing the distribution of stress across the jaws showed similar patterns in Titanichthys and the basking shark, reinforcing this comparison.

It has been established that there were almost certainly giant suspension-feeding vertebrates living 380 million years ago, at least 150 million years before the suspension-feeding Pachycormidae (previously the earliest definitive example) and about 350 million years before the first baleen whales.

The research team believes that there are other extinct species that would have filled a similar ecological role, including other placoderms (armoured fish) and at least one species of plesiosaur.

Sam Coatham added: “Our methods could be extended to identify other such species in the fossil record and investigate whether there were common factors driving the evolution and extinction of these species.

“We suggest a link between oceanic productivity and the evolution of Titanichthys, but this should be investigated in detail in the future. An established link could have implications for our understanding of the conservation of modern suspension-feeders.”

Southern right whale migration, new research


This 2011 video says about itself:

National Geographic photographer Brian Skerry describes a magical but risky experience photographing an enormous right whale off the coast of New Zealand.

From the British Antarctic Survey:

Migratory secrets of recovering whale species

May 19, 2020

Scientists have discovered where a whale species that feeds around the sub-Antarctic island of South Georgia breeds during the winter months. This understanding of where the animals migrate from will enable conservation efforts for their recovery from years of whaling. The results are published this week (20 May 2020) in the Journal of Heredity.

Southern right whales were hunted to near extinction after centuries of whaling. In the most comprehensive study of its kind, 30 researchers from 11 countries studied 15 skin samples from whales feeding around the sub-Antarctic island of South Georgia and compared them to 149 samples collected from around Argentina and Brazil and South Africa where the whales breed and give birth to their calves. New samples were collected from South Georgia during an expedition led by the British Antarctic Survey in 2018 and were combined with samples held by a network of collaborators across the globe.

Using a new genetic tool, the team discovered that most of the animals visiting South Georgia were calved around South America and not South Africa. This had previously been suspected, but not confirmed.

Lead author Dr Emma Carroll, from University of Auckland says: “Genetic methods are important in linking whale breeding grounds, areas that are closely monitored for population recovery, with feeding areas that are being and will be impacted by climate change. It is only by understanding these links that we can understand how whale populations will fare in a changing world.”

Collaborating with Chilean colleagues, the team also analysed the first-ever DNA sample from the Critically Endangered Chile-Peru southern right whale population. They found genetically, the Chile-Peru whale is a mixture between Indo-Pacific and Atlantic calving grounds, suggesting Chile-Peru has acted as a ‘stepping stone’ between these two areas.

Whale ecologist and senior author Dr Jennifer Jackson, at British Antarctic Survey, who led the project, says: “This is an important part of the jigsaw in understanding the geographical range of southern right whales. Identifying the migratory links of recovering whale populations is crucial to build accurate assessments of how well whale populations are recovering, and to understand how vulnerable these populations are to anthropogenic threats through their life cycle.

“There have been unexplained high whale calf mortalities around Argentina in the Península Valdéz region over the last 17 years, so there is a lot of work to be done to protect this species throughout their migratory range.”

The team are also tracking the movements of two South Georgia right whales in real time using satellite tags. One whale is already migrating towards the South American coast, providing further evidence of the migratory connection. Follow these whales here.

Notes

  • Southern right whales were so named because they were the ‘right’ whale to hunt, and in the South Atlantic they have been heavily exploited for over 350 years, with catches peaking in the mid 1800s. Only in the past three decades, have southern right whales again become regular winter visitors to Argentina, Brazil and South Africa, where they use sheltered bays to calve. Another population to the west, in Chile and Peru, has not fared so well, and the lack of recovery from whaling has led this population to be declared ‘Critically Endangered’ by the IUCN.
  • In 2009, the global estimate of southern right whales was estimated as 13,611 and the calving grounds in Argentina and Brazil was 4,029.
  • The Wild Water Whales project has been running since December 2016, and focusses on studying the population recovery and health of southern right whales in South Georgia waters. The project involves sightings surveys, using acoustic methods to find whales, collecting photo-identifications and skin samples to identify individuals, tracking whales to find out where they feed, and studying the health condition of right whales using drone technology.
  • Historically, the seas around South Georgia are a key feeding ground for multiple whale species, including the southern right, humpback, blue and fin whales. The area is abundant with food in summer, namely krill, a shrimp-like crustacean, which provides a key part of their diet.
  • Led by British Antarctic Survey, the South Georgia Wild Water Whales project has been funded by an EU BEST Medium grant, the Darwin Initiative, South Georgia Heritage Trust, Friends of South Georgia Island and the World Wildlife Fund.
  • The project used a new genetic tool for population visualisation and assignment (GENEPLOT) which estimated how well for example samples from South Georgia could be assigned to wintering ground datasets from Brazil, Argentina and South Africa.

‘No Russian roulette with British footballers’ health’


This 18 May 2020 British TV video says about itself:

Troy Deeney Worries Footballers Will Be Blamed for Wasting Covid-19 Tests | Good Morning Britain

Today Premier League clubs are expected to vote on whether to return to non-contact training. Watford captain Troy Deeney says he is not even talking about football at the moment and won’t put his family at risk.

Dutch NOS radio says that at Watford Football Club, three people are infected with COVID-19. There are also cases at Burnley and an unnamed other club. They write (translated):

Watford captain Troy Deeney revealed yesterday that he will not resume training. He doesn’t want to risk infecting his son with the coronavirus. His five-month-old baby is struggling with breathing problems. “I have already lost my father, grandmother and grandfather. Almost everyone I care about. That is more important to me than a few pence,” said Deeney in the podcast Talk The Talk. “You only need one person to get infected. I don’t want to take that virus home.”

Cats better venomous snakebite survivors than dogs


This 2 April 2016 video from Australia says about itself:

Dog killed by brown snake

The neighbour’s dog went for a boredom trip around the block. Typically, when pet dogs get loose in rural areas, they harass various lizards, snakes and echidnas.

The Australian “Brown Snake” is the second most technically toxic land snake; being twice as toxic as a Taipan. This is why you should not try to grab it in your mouth, and let it bite your face 20 times.

Australians have the lowest level of snake deaths, per capita, compared to other snake infested countries. This appears mainly due to the Commonwealth Serum Labs, producing antivenoms. Experience has shown that Australians lack the motor skills to back away from a snake, and suffer a syndrome which compels them to move towards a snake, and hit it with objects. They usually risk their lives in this manner, because the snake may bite their dog.

From the University of Queensland in Australia:

Why cats have more lives than dogs when it comes to snakebite

May 18, 2020

Cats are twice as likely to survive a venomous snakebite than dogs, and the reasons behind this strange phenomenon have been revealed by University of Queensland research.

The research team, led by PhD student Christina Zdenek and Associate Professor Bryan Fry, compared the effects of snake venoms on the blood clotting agents in dogs and cats, hoping to help save the lives of our furry friends.

“Snakebite is a common occurrence for pet cats and dogs across the globe and can be fatal,” Dr Fry said.

“This is primarily due to a condition called ‘venom-induced consumptive coagulopathy’ — where an animal loses its ability to clot blood and sadly bleeds to death.

“In Australia, the eastern brown snake (Pseudonaja textilis) alone is responsible for an estimated 76 per cent of reported domestic pet snakebites each year.

“And while only 31 per cent of dogs survive being bitten by an eastern brown snake without antivenom, cats are twice as likely to survive — at 66 per cent.”

Cats also have a significantly higher survival rate if given antivenom treatment and, until now, the reasons behind this disparity were unknown.

Dr Fry and his team used a coagulation analyser to test the effects of eastern brown snake venom — as well as 10 additional venoms found around the world — on dog and cat plasma in the lab.

“All venoms acted faster on dog plasma than cat or human,” Mrs Zdenek said.

“This indicates that dogs would likely enter a state where blood clotting fails sooner and are therefore more vulnerable to these snake venoms.

“The spontaneous clotting time of the blood — even without venom — was dramatically faster in dogs than in cats.

“This suggests that the naturally faster clotting blood of dogs makes them more vulnerable to these types of snake venoms.

“And this is consistent with clinical records showing more rapid onset of symptoms and lethal effects in dogs than cats.”

Several behavioural differences between cats and dogs are also highly likely to increase the chances of dogs dying from venomous snake bite.

“Dogs typically investigate with their nose and mouth, which are highly vascularised areas, whereas cats often swat with their paws,” Dr Fry said.

“And dogs are usually more active than cats, which is not great after a bite has taken place because the best practice is to remain as still as possible to slow the spread of venom through the body.”

The researchers hope their insights can lead to a better awareness of the critically short period of time to get treatment for dogs envenomed by snakes.

“As dog lovers ourselves, this study strikes close to home but it also has global implications,” Dr Fry said.

“I’ve had two friends lose big dogs to snakebites, dying in less than ten minutes even though the eastern brown snakes responsible were not particularly large specimens.

“This underscores how devastatingly fast and fatal snake venom can be to dogs.”