Feeding performance of blue whales vary wide as a function of prey density and distribution, according to new research just published in Science Advances. Because rorqual whales are air-breathing divers that exhibit a high-cost feeding mechanism, they are under considerable pressure to optimize their foraging success by weighing oxygen use against possible energy gain. Blue whales, the researchers have found, follow a complex strategy of switching from conserving oxygen when prey quality is low, to intense foraging at the expense of oxygen when prey quality is high.
Scientists studying blue whales off California's coast discovered that blue whales modify the intensity of their efforts when hunting krill in order to conserve energy.
"We found that blue whales have a complex strategy of switching from conserving oxygen when prey quality is low, to intense foraging at the expense of oxygen when prey quality is high," said Elliott Hazen, research ecologist at the U.S. NOAA Fisheries' Southwest Fisheries Science Center and lead author of the study.
The wreckage was first discovered 56km south of Cairns in 35m of water by Cairns diver Kevin Coombs in 2013, but weather and planning challenges delayed the final dives to complete the investigation.
The A24-25 was part of a task force flying long‑range missions against Japanese shipping and submarines during World War Two. On 28 February 1943, Catalina A24-25 and its 11 aircrew were on a 17-hour mission to provide anti-submarine cover to a convoy heading for Milne Bay in Papua New Guinea.
The survey began in 1986 and is conducted every two to three years. It covers coastal waters from Florida, where coastal shark species concentrate during the winter and spring, north to Delaware, where many shark species migrate during spring and summer as more northerly waters warm. Following this migratory route, at this time of year, makes it easier to survey the whole population.
During their field work this summer NOAA scientists tagged 2,835 sharks, compared to the 1,831 tagged in the previous survey done in 2012.
Nanomia bijuga is part of a group of organisms, known as physonect siphonophores, a group of chain-like hydrozoan predators and a relative of jellies, anemones and corals.
The Flying Fortress took part in a raid on Palermo on April 18 1943 when it was attacked by several German ME-110 fighters that knocked out one of its engines. The aircraft, part of the 353rd Bomber Squadron of the American air force, crashed into the sea, with the loss of all nine crew.
The WW2 bomber was found a few months ago by a group Italian divers who are part of a project called “Shadows of the Deep”, which aims to locate the wrecks of planes and boats off Sicily.
Every summer, hundreds of whale sharks gather off the Yucatan Coast near the Mexican tourist hubs of Cancun, Isla Mujeres and Isla Holbox. The sharks congregate 32 km offshore to gorge on the eggs of a fish called the little tunny, skimming them from the ocean’s surface with enormous, gaping mouths. In recent years, the spectacle has attracted legions of tourists to snorkel alongside the graceful, slow-moving giants.
There have been many reports of distressed marine animals, including manta rays, whales, and dolphins, seeming to ask divers for help when encumbered by fishing gear. Here, a reef shark approaches divers for assistance.
The account adds to the evidence that sharks, too, have the ability to discern that humans can help them, and will.
Such crabs have specially evolved to a more compact size so that they can hide in the nooks and small spaces within the coral reefs.
However, as coral reefs are being progressively lost worldwide (by as much as 80 percent in the Caribbean), these crabs risk losing their homes.
This conclusion was reached after Post Doctoral Associate Dr Adiël A. Klompmaker and his team compiled the body size measurements of 792 species of prehistoric crabs and lobsters, and concluded that habitat appears to be a factor in the evolution of crustacean size.
During their molting season, the concentration of methyl mercury in the seawater at Año Nuevo State Reserve was 17 times higher than normal. Scientists then found the toxin inside the shedded skin and hair that had been taken for analysis.
The mercury in the elephant seals comes from the fish and mussels they consume, which themselves have been exposed to high mercury levels in the seawater.
In the past, coral research has focused on radar and sonar mapping of the seafloor. With this kit, which is being used for the first time, biological samples can also be collected for analysis.
Currently on board the Okeanos Explorer’s Hohonu Moana, the compact kit can quickly extract tissues and preserve the sample’s DNA for analysis. This enables scientists to archive large amounts of the genetic material. Doing so can reveal important information about the evolutionary relationships amongst species.
