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Post by Ceratodromeus on Sept 17, 2016 4:54:34 GMT 5
Video shows mans close encounter with a white shark in open water
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Post by elosha11 on Sept 25, 2016 6:01:58 GMT 5
NEW STUDY ON TRAITS OF CONVERGENT EVOLUTION FOUND IN LAMNID SHARKS AND TUNA.
phys.org/news/2016-09-great-white-sharks-tuna-genetics.htmlGreat white sharks and tuna share genetics that makes them super predatorsDespite evolving separately for 400 million years, some sharks and tuna share genetic traits linked to higher metabolism and quick swimming behaviour. Tuna fish and the lamnid group of sharks, which includes great white sharks, share some similar traits that help make them super predators, including their style of swimming and their ability to stay warm. Despite their genetic separation, new research led by Imperial College London reveals many genes in the two groups that give them this predatory edge. The genes, linked to similar traits such as metabolism, have been preferentially selected for in both groups – meaning that they are more likely to be passed on since they give the creature a survival advantage. The team also found one identical gene in both groups that is linked with metabolism, and the creatures' ability to produce energy. This finding could help scientists unravel the relationship between genetics and physical traits. The research is published this month in Genome Biology and Evolution. Study co-author Professor Vincent Savolainen from the Department of Life Sciences at Imperial said: "Lamnid sharks and tuna both have stiff bodies and tails that allow them to swim in bursts. They can also keep their temperature up in colder waters. Both of these things make them more effective predators, allowing them to snatch prey in usually inhospitable waters. "These are simple traits, and ones that have evolved twice. They give us a great point to start really examining the underlying genetics and understanding the relationship to physical traits." Genes in the body code for different proteins, the building blocks of all tissues and functions in the body. When a gene is activated, and produces proteins, the process is called gene expression. However, it is difficult to directly link a single gene to a physical trait, such as metabolism, because gene expression can be different in different organisms, causing the resulting trait to be different. Looking at examples of the same gene used in two different animals can provide scientists with important clues as to how the expression of a gene relates to the physical trait observed. Lamnid sharks and tuna fish both have very different lifestyles and bodies to other fish, but are remarkably similar to each other. This provides an ideal scenario for scientists to look for the convergence of genes and physical traits. The team obtained samples of muscle tissue from three species of lamnid sharks and six species of tuna, as well as a closely related mackerel species, and looked at all the genes that were expressed. While complex experiments are needed to know exactly what each gene does, the researchers could see genes that were associated with similar processes involving metabolism being preferentially selected in the sharks and tuna, but not the mackerel. Explore further: Research team finds mice and humans express genes differently More information: Adam G. Ciezarek et al. Substitutions in the glycogenin-1 gene are associated with the evolution of endothermy in sharks and tunas, Genome Biology and Evolution (2016). DOI: 10.1093/gbe/evw211 Read more at: phys.org/news/2016-09-great-white-sharks-tuna-genetics.html#jCp |
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Post by Ceratodromeus on Nov 17, 2016 9:17:41 GMT 5
White shark attacks seal in the Columbia river
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Post by Ceratodromeus on Nov 22, 2016 22:28:12 GMT 5
Newly tagged great white shark recorded off Virginia coast
"Scientists are tracking a great white shark named Yeti that has been recorded swimming in the Atlantic Ocean off Assateague Island in Virginia. OCEARCH, an organization that shares real-time data through its global shark tracker, says a tracking device attached to the female juvenile shark pinged off the lower Eastern Shore on Thursday News outlets report Yeti was tagged Oct. 7 off Nantucket, Massachusetts. The shark weighs 960 pounds and is 11 feet long. Other sharks that OCEARCH is tracking including Mary Lee, who pinged off Savannah, Georgia, on Monday and Hudson, a juvenile male that was near Virginia's Chincoteague Island on Nov. 11." www.winchesterstar.com/associated_press/virginia/newly-tagged-great-white-shark-recorded-off-virginia-coast/article_f2903d59-9557-5ca7-974f-bfaf6e248157.html
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Post by elosha11 on Jan 6, 2017 0:09:31 GMT 5
Article today documenting a (presumably) great white attack on a near full grown 12 foot long bull elephant seal off Central Coast California. Attacks and predation on large bull elephant seals are somewhat uncommon, but they do occur. www.sanluisobispo.com/news/local/community/cambrian/article124319429.html) Shark activity off the Central Coast hit close to home for a bull elephant seal at Piedras Blancas, which was injured by an apparent shark bite. Christine Heinrichs, a Friends of the Elephant Seal docent and columnist for The Cambrian, shot photos of the elephant seal Monday, which had a fresh wound on its tail. “Monday at Piedras Blancas bluff, I saw things I’ve never seen before,” Heinrichs wrote in an email. “I’ve seen healed scars from shark attacks, but this bull has a fresh wound. Such attacks are unusual because big bull elephant seals can be formidable foes for sharks: “They’re massive and have big teeth,” said Brian Hatfield, wildlife biologist with the U.S. Geological Survey at Piedras Blancas, north of San Simeon. Heinrichs said the size of larger seals usually discourages sharks from attacking. “Younger seals, juveniles weighing 1,000 to 2,000 pounds, are usually considered more desirable prey, for exactly that reason,” she said. “A big bull can turn around and bite his attacker. An injured shark is effectively a dead shark.” Hatfield said the incident was “unusual but not unheard of,” estimating that the seal was not quite full grown, but still “a big guy” with “plenty of fat on him” — perhaps 6 or 7 years old and 12 feet long. Fully mature male elephant seals typically weigh more than 5,000 pounds. Hatfield said he usually sees two or three such incidents in a year, and no more than four. The shark’s strategy when hunting such an animal, he said, is to “make a big hit or powerful strike, then back off and let it bleed out.” |
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Post by Grey on Mar 1, 2017 1:22:48 GMT 5
Research article: Rare giants? A large female great white shark caught in Brazilian watersAbstractHere, we document an historical record of a large great white shark (GWS) captured in southern Brazilian waters, including morphometric measurements, basic biological data on internal organs and stomach contents. The captured shark was a female of 530 cm TL (503 cm fork-length), with an estimated total body weight of 2.5 tons. The stomach contained six shark heads, the remains of two dolphins and one teleost fish. The estimated hepatic somatic index (HSI) was 27%, and to our knowledge, represents the largest liver scientifically documented for this species to date. White sharks are known to undertake large-scale oceanic and transoceanic migrations. It is possible that the occasional records of white sharks off Brazil, previous records from Argentina and Uruguay, and an individual captured of Tristan da Cunha may be linked to migratory movements in the South Atlantic. Citation: Amorim, A. F., Arfelli, C. A., Bornatowski, H., & Hussey, N. E. (2018). Rare giants? A large female great white shark caught in Brazilian waters. Marine Biodiversity, 48(3), 1687-1692.LINK: link.springer.com/article/10.1007/s12526-017-0656-9--- ---
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Post by elosha11 on Apr 2, 2017 2:28:33 GMT 5
Pretty cool article and video showing a great white chasing and catching a seal. It's a pretty good example of the turning radius and agility of the shark. While it's true that the shark often doesn't want to waste the energy and time to chase a seal fully aware of its presence, this video (and others posted before) show that a great white determined to catch a seal - even a seal fully engaged in trying to escape - can be a deadly opponent for the pinniped. www.mirror.co.uk/news/weird-news/great-white-shark-filmed-devouring-10137752 |
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Post by elosha11 on Mar 21, 2018 22:14:06 GMT 5
Some new videos of great white predation on sizeable elephant seals. In the second, third, and fourth video, note that the killing bite appears to have been at the head/chest of the elephant seal rather than the tail, and almost decapitated the seal. See the last video for this. The first video is at Guadalupe, the last three are the same incident off Santa Barbara Island, CA. In the second incident, judging by the shape of the animal's head and comparative size to the great shark (described separately by the videographer as a 16-17 foot female shark), I'd think the elephant seal is a sizeable subadult male elephant seal, probably upwards of one ton.
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Post by creature386 on Jun 7, 2018 16:35:08 GMT 5
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Post by elosha11 on Mar 12, 2019 22:08:03 GMT 5
From EarthSky.org website and numerous other sources.
Great white shark genome decoded
By Eleanor Imster in EARTH | March 3, 2019
In a major step toward understand the biology of the great white shark, its entire genome has now been decoded in detail.
The iconic predator – whose ancestry dates back more than 400 million years – is famous not just for its massive size (up to 20 feet or 6.1 meters) and fierceness, but also for its wound-healing abilities, long lifespan (70-odd years), and low rates of cancer.
The new study, published February 19, 2019, in the peer-reviewed journal Proceedings of the National Academy of Sciences, compared the great white’s genome to genomes from a variety of other vertebrates, including the giant whale shark and humans. It turns out that the great white’s genome is massive – they have 41 pairs of chromosomes compared to our 23 — and the researchers say that decoding their genome could help reveal the genetic changes behind the shark’s evolutionary success.
The researchers say this information could help with the conservation of great whites and other sharks – many of which have rapidly declining populations due to overfishing – and humans as well. Salvador Jorgensen, a senior research scientist at the Monterey Bay Aquarium, is a study co-author. He said in a statement:
Decoding the white shark genome is providing science with a new set of keys to unlock lingering mysteries about these feared and misunderstood predators – why sharks have thrived for some 500 million years, longer than almost any vertebrate on earth.
The researchers found striking occurrences of specific DNA sequence changes indicating molecular adaptation (also known as positive selection) in numerous genes with important roles in maintaining genome stability - the genetic defense mechanisms that counteract the accumulation of damage to a species’ DNA, thereby preserving the integrity of the genome.
These adaptive sequence changes were found in genes intimately tied to DNA repair, DNA damage response, and DNA damage tolerance, among other genes. The opposite phenomenon, genome instability, which results from accumulated DNA damage, is well known to predispose humans to numerous cancers and age-related diseases.
The new genome map reveals that not only do great white sharks have chunks of code for these genome-stabilizing DNA repair mechanisms, but they also have gene adaptations for for tumor suppression. Michael Stanhope, of Cornell University College of Veterinary Medicine, is a study co-author. Stanhope told Wired:
Understanding how these genes might be inoculating these animals from cancer could be a huge benefit to humans.
The shark genomes also revealed intriguing evolutionary adaptations in genes linked to wound healing pathways. Sharks are known for their impressively rapid wound healing. Stanhope said:
We found positive selection and gene content enrichments involving several genes tied to some of the most fundamental pathways in wound healing, including in a key blood clotting gene. These adaptations involving wound healing genes may underlie the vaunted ability of sharks to heal efficiently from even large wounds.
The researchers say they have just explored the “tip of the iceberg” with respect to the white shark genome. Mahmood Shivji is a study co-author and director of Nova Southeastern University’s Save Our Seas Foundation Shark Research Center. Shivji said:
Genome instability is a very important issue in many serious human diseases; now we find that nature has developed clever strategies to maintain the stability of genomes in these large-bodied, long-lived sharks. There’s still tons to be learned from these evolutionary marvels, including information that will potentially be useful to fight cancer and age-related diseases, and improve wound healing treatments in humans, as we uncover how these animals do it.
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Post by elosha11 on May 3, 2019 21:54:43 GMT 5
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Post by sam1 on May 4, 2019 3:26:45 GMT 5
Yeah I saw it also today and wanted to post it.
Impressive. It just needs to be noted that it was likely not 3.5m-4m great white, as bigger individuals furn from fish to fat richer sources of food such as seals and whale carcasses scavenging.
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Post by elosha11 on May 5, 2019 0:25:44 GMT 5
^Yes, it was described as around a 2 meter shark in the article.
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Post by elosha11 on Jun 30, 2019 16:05:45 GMT 5
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Post by sam1 on Aug 2, 2019 23:27:07 GMT 5
..nevermind the teasing title, this is(as is always the case on that channel) a top notch content absolutely worth watching.
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