Saturday, 6 October 2018

Giant Isopod


Giant Isopod
Looking like it just crawled out of a bad science fiction movie, the giant isopod is without a doubt one of the strangest creatures found in the deep sea. Known scientifically as Bathynomus giganteus, it is one of about nine members of the genus Bathynomus. It is also the largest known members of the isopod family, a group of crustaceans closely related to shrimps and crabs. The giant isopod is also related to the small pillbugs that you can find in the garden. In fact, this insect-like creature is sometimes referred to as the giant pillbug. Giant isopods are not usually fished commercially, although some can be found in the occasional oceanside restaurant in northern Taiwan, where they are boiled and served with rice.

The enormous size of the giant isopod is a result of a phenomenon known as deep sea gigantism. This is the tendency of deep sea crustaceans and other animals to grow to a much larger size than similar species in shallower waters.

The giant isopod can grow to a length of over 16 inches, which makes it one of the largest members of the crustacean family. Like its terrestrial cousin, the pillbug, the giant isopod's body is protected by a hard shell that is divided into segments. This allows it to be strong and flexible at the same time. When threatened, this animal can roll itself into a ball to protect its vulnerable underside. And just like its land-based counterpart, the isopod has compound eyes, with over 4,000 individual facets. This gives the animal a large field of view, and makes it extremely sensitive to fast movements. Because light is extremely faint in the deep sea, the giant isopod has developed large antennae to help it feel its way around as it crawls along the ocean floor.

The giant isopod is a carnivorous crustacean that spends its time scavenging the deep sea floor. Food is extremely scarce at these great depths, so the isopod has adapted to eat what ever happens to fall from above. This includes the bodies of dead whales, fish, and squid. It is believed that the isopod will also feed on some slow-moving animals such as sea cucumbers and sponges. The giant isopod has a complex mouth that with many components that work together to pierce, shred, and disembowel their prey. The isopod can go for long periods of time without eating and has been known to survive over eight weeks without food in when kept in captivity.

Giant isopods reproduce by laying eggs. These eggs are thought to be the largest of all the marine invertebrates. The females develop a pouch known as a marsupium, where the eggs are stored until the young are ready to emerge. When this happens, the young isopods escape from the marsupium as fully formed miniatures of the adults. At this stage, they are known as manca and are nearly fully developed. Bypassing the larval stage greatly enhances the young isopod's chances of survival.

Info source:
http://www.seasky.org/deep-sea/giant-isopod.html

Gif via imgur

#biodiversity #coolcritters #giantisopod #science #biology #marinecritters

Leidenfrost wheels


Leidenfrost wheels
Leidenfrost drops – which skitter almost frictionlessly across extremely hot surfaces on a thin layer of their own vapor – are notoriously mobile. We’ve all seen numerous methods of controlling their propulsion, often using specially-shaped surfaces. But it turns out that some Leidenfrost drops can self-propel even on a smooth, flat surface.

Internally, large Leidenfrost drops have complicated, but symmetric flows that are driven by temperature and surface tension variations across the drop. But as the drop evaporates, that symmetry eventually gets broken, leaving behind a single large circulating flow.

Beneath the drop, that internal circulation affects the vapor layer. It causes the layer to take on an overall tilt, and the rotation, along with that slight angle in the vapor layer, causes the Leidenfrost drop to roll away like a wheel.

Image and research credit: A. Bouillant et al.; via NYTimes

Journal article
https://www.nature.com/articles/s41567-018-0275-9

Source:
https://www.nytimes.com/2018/09/14/science/leidenfrost-effect.html

#physics #leidenfrosdroplets #science

Dust Storms Raised by Strong Winds on Titan


Dust Storms Raised by Strong Winds on Titan
Earth and Mars are well-known for their dust storms, but a new source of extraterrestrial dust storms is joining them: Saturn’s moon Titan. Titan already shares unusual similarities to Earth: it is the only other place known to currently have stable liquid bodies at its surface. On Earth, water makes up our lakes and oceans; on Titan, it’s methane.

The evidence that Titan may also have dust storms dates from several Cassini flybys in 2009 and 2010. Cassini observed short-lived infrared bright spots in a dune-covered equatorial region. After considering several other possible sources for these temporary bright spots, researchers concluded that the most likely explanation was dust clouds suspended by high winds. This suggests that the dune fields on Titan are still actively changing, just like those on Earth and Mars!

Image credit: artist’s concept for Titan dust storm - NASA/ESA/IPGP/Labex UnivEarthS/University Paris Diderot;
Research credit: S. Rodriguez et al.;
https://www.jpl.nasa.gov/spaceimages/details.php?id=PIA22482

#nasa #space #Titan #Cassini #universe #science