All posts tagged: marine biology

First epigenetic DNA clock can reveal a zebra shark’s age from a blood sample

First epigenetic DNA clock can reveal a zebra shark’s age from a blood sample

Published by Jenni Sidey

Zebra sharks carry age-related chemical changes in their DNA that can estimate how old they are with surprising accuracy. A model using only 10 DNA markers came within about 1.6 years of the true age, while larger models reduced the typical error to about one year. The blood-based method could help conservationists measure shark population ages without killing animals, although accuracy drops in older and wild-caught sharks. A shark’s age can be surprisingly hard to pin down, even when the animal is swimming in plain sight. For zebra sharks, researchers have now found a clue in blood: chemical marks on DNA that shift as the animals grow older. A University of Georgia team built what it describes as the first epigenetic clock tested in sharks. The method estimates age by reading DNA methylation, chemical tags that change across the genome over time. Published in Molecular Ecology, the work could give conservation biologists a less harmful way to estimate shark ages. Age structure can reveal whether a population is growing, stable or declining. “Age structure is …

150-year-old Greenland shark washed ashore in Ireland, offering new clues to healthy aging

150-year-old Greenland shark washed ashore in Ireland, offering new clues to healthy aging

Published by Jenni Sidey

A Greenland shark stranded in Ireland was more than 150 years old but may have only just reached reproductive age. Its eyes, DNA-repair systems and scarred 34-kilogram heart offer clues to how the species remains functional for centuries. Scientists found no clear cause of death, but preserved tissues may improve ageing research and conservation of the poorly understood shark. A three-metre Greenland shark lay on tidal flats in County Sligo in April 2026, far from the deep northern waters where its species usually lives. Its arrival marked Ireland’s first recorded stranding of a Greenland shark and opened an unusual window into one of the ocean’s least understood giants. The shark weighed more than 200 kilograms and was estimated to be over 150 years old. For humans, that age seems extraordinary. For a Greenland shark, it may represent only the beginning of adulthood. “It’s such a pity. This guy – it took him 150 years to get to the point where he could have reproduced, could have contributed to get the population on track, and may …

Gulf of California orcas use precision strikes to explode sunfish into thousands of pieces

Gulf of California orcas use precision strikes to explode sunfish into thousands of pieces

Published by Jenni Sidey

Orcas in the Gulf of California were recorded using a coordinated “ram-to-fragment” technique on dead sharp-tail sunfish. One orca held the carcass steady while another struck it at high speed, breaking the tissue into thousands of smaller pieces. Juvenile orcas fed on the fragments, suggesting the behavior may help younger animals eat, though it could also involve play or social learning. Two events, recorded in 2024 and 2025, suggest a newly documented prey-processing strategy that researchers now hope to study across more pods and sunfish species. Orcas in the Gulf of California Orcas in the Gulf of California have been seen using a brutal but precise way to process sharp-tail sunfish. One whale holds the carcass steady, another charges at speed, and the impact blasts the flesh into thousands of drifting pieces. The behavior, described in Frontiers in Ethology, was recorded during two separate encounters more than a year apart. Both involved coordinated ramming after the sunfish had already been killed and opened. “We document how one orca holds the sunfish and lets go just …

Tunas became large, warm-blooded predators long after the dinosaur extinction

Tunas became large, warm-blooded predators long after the dinosaur extinction

Published by Jenni Sidey

Tunas did not become large, fast and warm-blooded simply because an asteroid cleared the oceans of competing predators. Their defining traits appeared separately over tens of millions of years, complicating a familiar story about life after mass extinction. The asteroid impact 66 million years ago erased non-avian dinosaurs and many large marine predators. One long-held explanation proposed that tunas and other powerful fishes quickly expanded into the empty ecological roles. A new analysis from Yale University challenges that idea. By combining genetic evidence with fossils, researchers built the most complete time-calibrated evolutionary tree yet for Scombridae, the family that includes tunas, mackerels, bonitos and related fishes. The tree places the family’s origin near the Cretaceous-Paleogene extinction. Yet the traits that make modern tunas exceptional did not appear together or immediately afterward. Three independent origins of endothermy in Scombridae. Time-calibrated phylogeny of Scombridae estimated using a Bayesian node-dating approach, with branches coloured according to an ancestral state reconstruction of endothermy. (CREDIT: Proceedings of the Royal Society B) “Our results demonstrate the K-Pg extinction did not trigger …

Walking shark found in Papua New Guinea is new to science

Walking shark found in Papua New Guinea is new to science

Published by skeptic

The newly identified walking shark, Hemiscyllium dudgeonae MV Erdmann A shark that can walk with most of its body out of the water, found on the shores of Papua New Guinea, has been identified as a new species. Locals have long been aware of the strange fish, which they sometimes see waddling across reef flats at low tide. They call it kadedekedewa, which means “dog shark” or “lazy shark”. Sharks in the genus Hemiscyllium, commonly known as walking sharks or epaulette sharks, use their pectoral fins like legs to move around and are only known to be in Australia and New Guinea. The new species has been named Hemiscyllium dudgeonae after Christine Dudgeon at the University of the Sunshine Coast in Queensland, Australia, who was part of the team that formally identified it. She first encountered the shark after midnight one day in March 2025, swimming in just a metre of water covering a meadow of seagrass in Milne Bay, Papua New Guinea. Dudgeon was looking for a different species, Hemiscyllium michaeli, known to inhabit …

Arctic Ocean reaches tipping point that could be dire for marine life

Arctic Ocean reaches tipping point that could be dire for marine life

Published by skeptic

A phytoplankton bloom in the Arctic Ocean near Svalbard gives the sea a green hue visible in satellite images European Union, Copernicus Sentinel-2 imagery As sea ice melts, more light will infiltrate the Arctic Ocean, allowing phytoplankton and other marine life to flourish – or so we thought. In fact, phytoplankton growth in some parts of the Arctic is now starving other parts of a crucial nutrient, a tipping point that could spell trouble for seals, polar bears and even commercial fish in the north Atlantic. Phytoplankton, the tiny photosynthesising organisms that form the basis of the marine food chain, have been increasing across the Arctic, according to satellite measurements of the green pigment chlorophyll. Algal blooms there have broken records. But since 2009, overall phytoplankton growth has slowed in many areas and has even begun decreasing on the Atlantic side of the Arctic. New research by Raja Ganeshram at the University of Edinburgh, UK, and his colleagues suggests blooming phytoplankton on the Pacific side are depriving neighbouring areas of nitrate, a chemical that’s vital …

Deep-ocean cameras capture first-ever images of live Goblin shark

Deep-ocean cameras capture first-ever images of live Goblin shark

Published by Jenni Sidey

Goblin sharks have spent years in public imagination as something half-seen, half-legendary, a pale, long-snouted predator usually known from carcasses, fishing lines, and brief encounters near death. Now they have finally been seen alive where they actually live, deep in the ocean. As a result, that changes more than a shark checklist. A University of Hawaiʻi at Mānoa-led team has reported the first published live observations of goblin sharks, Mitsukurina owstoni, in their natural deep-sea habitat. The paper, published in the Journal of Fish Biology, describes two separate sightings. One was near Jarvis Island in 2019, and another was on the slope of the Tonga Trench in 2024. For a species often called a “living fossil,” the footage fills in a major blank. Goblin sharks are the only living members of their family, a shark lineage dating back nearly 125 million years. Lead author Aaron Judah, a doctoral candidate in the Deep-Sea Fish Ecology Lab and the Deep-Sea Animal Research Center in the Department of Oceanography at the University of Hawaiʻi at Mānoa, said the …

Millions of fossil whale bones found in deep-ocean ‘necropolis’

Millions of fossil whale bones found in deep-ocean ‘necropolis’

Published by skeptic

Fossils including possible baleen-whale ribs found at a depth of 5656 metres in the Indian Ocean Global TREnD, IDSSE The world’s deepest known whale graveyard has been discovered in the southern Indian Ocean at a depth of 7 kilometres. The remains found there include a new species of extinct beaked whale and other fossils that are over 5 million years old. In early 2023, Peng Zhou at the Chinese Academy of Sciences and his colleagues undertook 32 dives in a crewed submersible along 1200 kilometres of the seafloor, in an area known as the Diamantina Zone. The expedition was part of the Global Hadal Exploration Programme, an effort led by Chinese scientists to explore all the deepest parts of the planet’s oceans, which range from 6000 to 11,000 metres below the surface. At these depths there is no light, and life must survive on what falls from the surface or generate its own energy from chemicals – known as chemosynthesis. The first fossil whales were found at a depth of 7002 metres in a part …

First test of CO2 removal with green sand finds no harm to marine life

First test of CO2 removal with green sand finds no harm to marine life

Published by skeptic

A beach in Southampton, New York, treated with olivine sand Chayenne Moreau The first trial to absorb atmospheric carbon dioxide by adding crushed olivine to the ocean had no adverse effects on the seafloor ecosystem in its first year. While the results of the trial in New York state are promising for this carbon-removal technique, researcherss warn they may not have captured all potential negative impacts. The addition of olivine to the ocean should still be carefully regulated, “but there might be ways that it could work and have a minimal effect”, says Emilia Jankowska at the non-profit group Hourglass Climate, who led the study. The United Nations climate body has said the world will need carbon removal methods, which range from planting trees to filtering out CO2 from the air with giant machines, to reach net-zero greenhouse gas emissions. As emissions continue to rise and the goal of limiting global warming to 1.5°C above preindustrial levels slips out of reach, many hope these technologies could someday help cool the planet back down. Olivine, or …