Rays look like bats in the water, and this is probably why they are called batoids. They have pectoral fins that are attached to their bodies from back to front, similar to the way a bat's wings attach from its shoulder to its feet.
The fins of the ray create a disk shape that can be round, triangular, or diamond-shaped. Rays use their pectoral fins to 'fly' through the water. Though a bony fish takes in water with its mouth, rays do not because they live at the bottom of the ocean. If they took in water through their mouths, they would probably just get a mouthful of sand. Because of this, they have breathing holes on top of their bodies called "spiracles". Rays use spiracles to take in water that is then sent over the gills.
Also, because they do not have a swim bladder, rays sink when they are not actively swimming.
Interestingly, rays are usually curious and social animals. Though they often live alone, they like swimming together in groups with other rays. Despite the fact that they are able to swim, most rays live at the bottom of the sea, eating benthic animals. In fact, they often flick sand on their backs to camouflage (disguise, or hide) themselves as they lie in the sand at the bottom of the ocean.
Tuna
Tuna, sometimes called tuna fish, are several species (kinds) of fish. They are in the family Scombridae, mostly in the genus Thunnus.
Tuna are fast swimmers. People have seen tuna swim at up to 77 km/h. Several species of tuna are warm-blooded. Most species of fish have white flesh. The flesh of the tuna is different. It is pink to dark red. This is because tuna muscle tissue contains greater quantities of myoglobin. Myoglobin is a molecule that binds oxygen. Some of the larger tuna species such as the Northern bluefin tuna can raise their blood temperature above the water temperature with muscular activity. This enables them to live in cooler waters and survive a wider range of circumstances.
Tuna is an important commercial fish. Some varieties of tuna, such as the bluefin and bigeye tuna are threatened by overfishing, dramatically affecting tuna populations in the Atlantic and northwestern Pacific Oceans. Other populations seem to support fairly healthy fisheries (for example, the central and western Pacific skipjack tuna), but there is mounting evidence that overfishing threatens tuna fisheries worldwide.
Some fishermen in Australia now grow Southern bluefin tuna in fish farms. Fish farms are areas of water with nets around them, where farmers raise (keep and grow animals) fish. Some tuna farms are circular nets 40 meters in diameter and 20 meters deep. The fishermen catch the tuna at sea, and then they keep the tuna in these farms. The tuna grow and get fatter for three to six months. There are also tuna farms in the Mediterranean, North America, and Japan that raise Northern bluefin tuna. Some environmental groups say that tuna farms use too much fish as food for the tuna, and that the farms pollute the water (make the water dirty).
Tuna are high up in the food chain. They eat animals that ate animals. Their diet leads to the accumulation of heavy metals in their flesh. Mercury levels can be relatively high in some of the larger species of tuna such as bluefin and albacore. As a result, in March 2004 the United States FDA issued guidelines recommending pregnant women, nursing mothers, and children to limit their intake of tuna and other types of predatory fish . However, most canned light tuna is skipjack tuna and is very low in mercury.
Sport fishermen like to catch tuna using rods and hooks.
There are eight species:
Species of several other genera (all in the family Scombridae) have common names containing "tuna":
Fishing hook
A fishing hook is a hook used to catch fish. There are many types of fishing hooks. Most have a sharp point which sticks into the fish when it is caught. There are lots of types of fishing hooks, and they all depend on how powerful they can hold the line and the size. Many hooks have different sizes for different fish.
Fishing rod
A fishing rod is a tool used for catching fish. The rod is often used to cast an artificial bait to where the fish are. This is the way people catch fish for fun or sport. Commercial fishing is usually done using fishing nets.
A fishing rod is a line with bait on it, fixed on a pole. There is usually some way to make the line longer or shorter, and the pole it is fixed on can bend a little.
Mammalia (taxonomy)
"See Mammals for more info"
"Class:" Mammalia:
Nottuln
Nottuln is a town in Coesfeld county, 20 km west of Münster, Germany.
It consists of
A church was founded in 860 by Ludger Liudger, as well as the first monastery in Westphalia.
After a big fire 1748 it was built up by Johann Conrad Schlaun.
The county of Nottuln is at the A43 and a railway.
Coesfeld
Coesfeld is a town in North Rhine-Westphalia, Germany and the capital of Coesfeld county.
Nepomucenum and St.-Pius-Gymnasium are highschools in Coesfeld.
Coesfeld was founded by the holy Ludgerus. Coesfeld has been a town since 1197.
Big villages in county Coesfeld:
St.-Pius-Gymnasium
St.-Pius-Gymnasium is a catholic private highschool in Coesfeld near Münster in Germany. It is held by the diocese of Münster and named after Pope Pius X. . Until 1976 the school was a boarding school only for boys. Since then it has been a "Gymnasium". Today, there are 791 pupils.
There is a statue of Pius X on the school ground to express solidarity with the patron. The school has a chapel and a pastor. There is a modern, well-equipped assembly hall, too.
St.-Pius-Gymnasium is associated with the Lyceé Notre-Dame in Guingamp (France), offers trips to Poole (England) and tries to establish a partnership with a school in Orlando (Florida, USA).
In Advent, the school publishes a yearbook named "Piusbrief". Its pupil magazine "Fünf vor Acht" got multiple honours.
The whole school is a non-smoking area.
Cell membrane
The cell membrane is a thin flexible layer around the cells of all living things. It is sometimes called the plasma membrane or cytoplasmic membrane.
Its basic job is to separate the inside of cells from the outside.
In all cells, the cell membrane separates the cytoplasm inside the cell from its surroundings. Animal cells are contained in just a membrane. Bacteria, fungi and plants have strong cell walls as well, which support the cell and block the passage of large molecules.
The membrane is made up of a thin layer called the 'phospholipid bilayer'. This has two layers of phospholipid molecules with phosphate heads on the surfaces and lipid (oil) tails on the inside. The outside heads mix with water, but the tails reject water.
Other proteins and lipids can be added to the cell membrane. By these changes, the cell can adjust what it brings in or puts out. Some proteins are always stuck into it, these are called "integral" membrane proteins. It also has some which are only sometimes stuck onto it. These are called peripheral membrane proteins. The outer layer protecting the inner cell.
The membrane is selectively permeable. It is active and regulates (adjusts) what comes in and what goes out of the cell. The movement of substances across the membrane can be either "passive", occurring without the input of cellular energy, or "active", requiring energy.
Proteins within the membrane are key to its working. These proteins mainly transport chemicals and information across the membrane.
The membrane contains many proteins. The surface proteins can act as gates. They let some chemicals into the cell and let other chemicals leave the cell. It is estimated that up to a third of the human proteome may be membrane proteins. Some of these proteins are linked to the exterior of the cell membrane. An example of this is the CD59 protein, which identifies cells as “self” and thus inhibits their destruction by the immune system.
Morocco