KOLKATA: The absence of a clear motive and strong indication that an “insider” might be involved in the murder of an elderly citizen at Deshapriya Park has sent neighbours of this upscale locality in shock. What adds to their anxiety is that Ranajit Chatterjee was being pursued by local promoters for the last two years to sell off his ancestral property worth crores now. Chatterjee refused. Police say his daughter cannot recall if he was ever threatened for this, but they will investigate this angle. “After what transpired at Short Street, we can hardly take a chance,” said a senior officer. Local residents – including actor Biplab Chatterjee – say […]

Tropical seas are ecological hotspots where predators should be active and easy to catch – but 50 years of data shows sharks are easier to catch in cooler seas

The age of a whale shark can be determined by dating the rings of growth in their cartilage, a method that has confirmed that these animals can live for at least 50 years

Imants G. Priede, Rhoderick W. Burgass, Manolis Mandalakis, Apostolos Spyros, Petros Gikas, Finlay Burns, and Jim Drewery

Whereas upper ocean pelagic sharks are negatively buoyant and must swim continuously to generate lift from their fins, deep-sea sharks float or swim slowly buoyed up by large volumes of low-density oils in their livers. Investigation of the Pressure, Volume, Temperature (PVT) relationships for liver oils of 10 species of deep-sea Chondrichthyes shows that the density difference between oil and seawater, remains almost constant with pressure down to full ocean depth (11 km, 1100 bar); theoretically providing buoyancy far beyond the maximum depth of occurrence (3700 m) of sharks. However, , does change significantly with temperature and we show that the combined effects of pressure and temperature can decrease buoyancy of oil by up to 10% between the surface and 3500 m depth across interfaces between warm southern and cold polar waters in the Rockall Trough in the NE Atlantic. This increases drag more than 10 fold compared with neutral buoyancy during horizontal slow swimming (0.1 m s^–1) but the effect becomes negligible at high speeds. Chondrichthyes generally experience positive buoyancy change during ascent and negative buoyancy change during descent but contrary effects can occur at interfaces between waters of different densities. During normal vertical migrations buoyancy changes are small, increasing slow-speed drag by no more than 2–3 fold. Equations and tables of density, pressure and temperature are provided for squalene and liver oils of Chimaeriformes (Harriotta raleighana, Chimaera monstrosa, Chimaera monstrosa), Squaliformes (Centrophorus squamosus, Deania calcea, Centroscymnus coelolepis, Centroscyllium fabricii, Etmopterus spinax) and Carcharhiniformes (Apristurus laurussonii, Galeus murinus).

Itsumi Nakamura, Rui Matsumoto, and Katsufumi Sato

It is generally assumed that the body temperature of large animals is less likely to change due to their large body size, resulting in a high thermal inertia and a smaller surface area to volume ratio. The goal of this study was to investigate the stability of body temperature in large fish using data from field experiments. We measured the muscle temperatures of free-ranging whale sharks (Rhincodon typus), the largest extant fish globally, and investigated their ectothermic physiology and the stability of their body temperatures. The measured muscle temperature of the whale sharks changed substantially more slowly than the water temperature fluctuations associated with vertical movements, and the whole-body heat-transfer coefficients (HTC) of whale sharks estimated using heat-budget models were lower than those of any other fish species measured to date. The heat-budget models also showed that internal heat production does not contribute to changes in muscle temperature. A comparative analysis showed that the HTC at cooling in various fish species including both ectothermic and endothermic species ranging from 10^–4 to 10³ kg was proportional to body mass^–0.63. This allometry was present regardless of whether the fish were ectothermic or endothermic, and was an extension of the relationship observed in previous studies on small fish. Thus, large fish have the advantage of body temperature stability while moving in environments with large temperature variations. Our results suggest that the large body size of whale sharks aids in preventing a decrease in body temperature during deep excursions to more than 1000 m depths without high metabolic costs of producing heat.

David E. Cade, J. Jacob Levenson, Robert Cooper, Rafael de la Parra, D. Harry Webb, and Alistair D. M. Dove

Whale sharks (Rhincodon typus Smith 1828) – the largest extant fish species – reside in tropical environments, making them an exception to the general rule that animal size increases with latitude. How this largest fish thrives in tropical environments that promote high metabolism but support less robust zooplankton communities has not been sufficiently explained. We used open-source inertial measurement units (IMU) to log 397 hours of whale shark behavior in Yucatan, Mexico, at a site of both active feeding and intense wildlife tourism. Here we show that the strategies employed by whale sharks to compensate for the increased drag of an open mouth are similar to ram-feeders five orders of magnitude smaller and one order of magnitude larger. Presumed feeding constituted 20% of the total time budget of four sharks, with individual feeding bouts lasting up to 11 consecutive hrs. Compared to normal, sub-surface swimming, three sharks increased their stroke rate and amplitude while surface feeding, while one shark that fed at depth did not demonstrate a greatly increased energetic cost. Additionally, based on time-depth budgets, we estimate that aerial surveys of shark populations should consider including a correction factor of 3 to account for the proportion of daylight hours that sharks are not visible at the surface. With foraging bouts generally lasting several hours, interruptions to foraging during critical feeding periods may represent substantial energetic costs to these endangered species, and this study presents baseline data from which management decisions affecting tourist interactions with whale sharks may be made.

At the rate we’re killing them, we may soon see it firsthand.

An alarming case study in the North Atlantic bolsters Greenpeace's call for a Global Ocean Treaty.

When you create a law to regulate something, there's always the danger that people will drive a truck through the loopholes, adhering to the letter of the law but not its spirit.

A shark's fin is like its fingerprint, with each animal having its own unique patterns and scars.

Four species of walking sharks have been discovered in the waters off northern Australia and New Guinea.

This company seems to think there's a chance you'll be safer in the water if you look a teensy bit like a lionfish. We remain, um, skeptical.

NIK SIMON'S GAIN LINE: Sale Sharks are waiting in the wings if England star Jonny May does not sign a new contract with Leicester Tigers. The former Gloucester winger has reached a stand-off.

The Prime Minister's favourite team will begin their 2020 campaign against the South Sydney Rabbitohs - supported by opposition leader Anthony Albanese - at ANZ Stadium in Sydney.

Two players from the Cronulla Sharks have been sent home from team training after falling ill with flu-like symptoms.

Mr Morrison announced the government would ban 'non essential' public gatherings of more than 500 people in Australia from Monday.

The life-long Sharks fan had just hours before insisted he would attend his team's first NRL game of the season against the South Sydney Rabbitohs.

Every year, some 5.25 trillion new pieces of plastic debris are thrown into the ocean, much of which ends up being eaten by manta rays and whale sharks according to a new study from Indonesia.

Researchers have discovered multiple species of sharks in the waters off northern Australia and Indonesia that can use their fins to walk over sand and rocks in addition to swimming.

Researchers from the University of Bern, Switzerland, looked at records of attacks by large fish such as sharks on ocean fishing lines between 1960 and 2014.

These organisations are membership-based, many of which have operated for more than 50 years. They serve local communities or people who share a common bond.

Australian scientists found sharks incubated in tanks that simulate temperatures in 2100 became 'right handed', preferring to swim to the  right, a process known as lateralization.

It’s called a remora, and you’ve probably seen it before. It attaches to fish and marine mammals all the time. But get this: It doesn’t attach with its mouth. It’s got a suction cup it wears as a hat.

News stories on using pets in clinical trials to test veterinarian drugs, debunking the Piltdown Man once and for all, and deciding just how smart crows can be, with David Grimm.   From the magazine It’s really difficult to figure out how old a free-living animal is. Maybe you can find growth rings in bone or other calcified body parts, but in sharks like the Greenland shark, no such hardened parts exist. Using two different radiocarbon dating approaches, Julius Neilsen and colleagues discovered that the giant Greenland shark may live as long as 400 years.   Read the research.   [Image: James Howard McGregor/Wikimedia Commons/Music: Jeffrey Cook]

This week, we chat about a blood test that could predict recovery time after a concussion, new insights into the bizarre hagfish’s anatomy, and a cheap paper centrifuge based on a toy, with Online News Editor David Grimm. Plus, Science’s Alexa Billow talks to Christian Koerner about why just planting any old tree isn’t the answer to our carbon problem.    Listen to previous podcasts.   [Image: Bureau of Land Management Oregon and Washington; Music: Jeffrey Cook]

David Grimm—online news editor for Science—talks with Sarah Crespi about two underwater finds: the first sharks shown to survive off of seagrass and what fossilized barnacles reveal about ancient whale migrations. Sarah also interviews Staff Writer Adrian Cho about what happens after quantum computing achieves quantum supremacy—the threshold where a quantum computer’s abilities outstrip nonquantum machines. Just how useful will these machines be and what kinds of scientific problems might they tackle? Listen to previous podcasts.  [Image: Aleria Jensen, NOAA/NMFS/AKFSC; Music: Jeffrey Cook]

McKeever, William, author

Jaiteh, Vanessa Flora, author