Starsglaxiesspace - SPACE

Subphylum Urochordata

Subphylum Urochordata (also called Tunicata) includes tunicates, salps, and larvaceans. This subphylum, along with subphylum Cephalochordata, is informally classified under protochordates. Protochordates are “primitive” chordates that are not vertebrates. Most adult tunicates are sessile and do not show chordate characteristics. However tunicates have a free-swimming larval stage that exhibits all chordate characteristics. Tunicates get their name from the outer covering, called a tunic, which cloaks their body.

The first two photos show pictures of tunicate larva. The next three photos show pictures of adult tunicates.

The window for saving the world’s coral reefs is rapidly closing

The world’s reefs are under siege from global warming, according to a novel study published today in the prestigious journal Science

The world’s reefs are under siege from global warming, according to a novel study published today in the prestigious journal Science.

For the first time, an international team of researchers has measured the escalating rate of coral bleaching at locations throughout the tropics over the past four decades. The study documents a dramatic shortening of the gap between pairs of bleaching events, threatening the future existence of these iconic ecosystems and the livelihoods of many millions of people.

“The time between bleaching events at each location has diminished five-fold in the past 3-4 decades, from once every 25-30 years in the early 1980s to an average of just once every six years since 2010,” says lead author Prof Terry Hughes, Director of the ARC Centre of Excellence for Coral Reef Studies (Coral CoE).

“Before the 1980s, mass bleaching of corals was unheard of, even during strong El Niño conditions, but now repeated bouts of regional-scale bleaching and mass mortality of corals has become the new normal around the world as temperatures continue to rise.”

The study establishes a transition from a period before the 1980s when bleaching only occurred locally, to an intermediate stage in the 1980s and 1990s when mass bleaching was first recorded during warmer than average El Niño conditions, and finally to the current era when climate-driven bleaching is now occurring throughout ENSO cycles.

The researchers show that tropical sea temperatures are warmer today during cooler than average La Niña conditions than they were 40 years ago during El Niño periods.

“Coral bleaching is a stress response caused by exposure of coral reefs to elevated ocean temperatures. When bleaching is severe and prolonged, many of the corals die. It takes at least a decade to replace even the fastest-growing species,” explained co-author Prof Andrew Baird of Coral CoE.

“Reefs have entered a distinctive human-dominated era - the Anthropocene,” said co-author, Dr C. Mark Eakin of the National Oceanic & Atmospheric Administration, USA. “The climate has warmed rapidly in the past 50 years, first making El Niños dangerous for corals, and now we’re seeing the emergence of bleaching in every hot summer.” For example, the Great Barrier Reef has now bleached four times since 1998, including for the first time during back-to-back events in 2016 and 2017, causing unprecedented damage. Yet the Australia government continues to support fossil fuels.

“We hope our stark results will help spur on the stronger action needed to reduce greenhouse gases in Australia, the United States and elsewhere,” says Prof Hughes.

IMAGE….A researcher from the ARC Centre of Excellence for Coral Reef Studies surveys the bleached/dead corals at Zenith Reef, Nov 2016. Credit Andreas Dietzel

Taurus constellation

Infraphylum Agnatha

Agnathans are a group of jawless fishes that include Myxini (hagfish) and Petromyzontidae (lampreys). Pictured above are Petromyzontidae, also known as lampreys.  The name “lamprey” is derived from Latin meaning “stone licker.” The most well known lamprey species are a parasitic and feed by boring into the flesh of other fish to suck their blood. However there are a some species of lamprey that non-parasitic.

Hubble-X in galaxy NGC 6822

The saying 'X' marks the spot holds true in this NASA/ESA Hubble Space Telescope (HST) image where Hubble-X marks the location of a dramatic burst of star formation, very much like the Orion Nebula in our Milky Way galaxy, but on a vastly greater scale.

(ESA/Hubble)  Hubble-X is a glowing gas cloud, one of the most active star-forming regions within galaxy NGC 6822. The name Hubble-X does not refer to the shape of the gas cloud, but rather is derived from a catalog of objects in this particular galaxy.

Credit: NASA/ESA and The Hubble Heritage Team (STScI/AURA)

About the Object Name: Barnard’s Galaxy, Hubble-X, NGC 6822 Type: Local Universe : Nebula : Type : Star Formation           Local Universe : Galaxy : Type : Barred           Local Universe : Galaxy : Type : Irregular Distance: 2 million light years ConstellatioSagittarius Category: Galaxies

Coordinates

Position  (RA):19 45 5.03 Position (Dec): -14° 43’ 20.00" Field of view: 1.09 x 1.01 arcminutes Orientation: North is 305.8° left of vertical

Source

Hubble Mosaic of the Majestic Sombrero Galaxy

credit: Patrice Paquette

NGC 2170