Most chitons are "nocturnal", so they feed at night, and hide under rocks during the day. Their main habitat is the intertidal zone. They live on hard surfaces, such as on or under rocks, or in rock crevices. Some species live quite high in the intertidal zone and are exposed to the air and light for long periods. Others live subtidally. A few species live in deep water, as deep as 6,000 m (about 20,000 ft).
Chitons have a relatively good fossil record, stretching back 400 million years to the Devonian. Before this, some organisms have been interpreted (tentatively) as stem-group polyplacophora; the record of polyplacophora stretches back to the Upper Cambrian.
"Kimberella" and "Wiwaxia " of the Precambrian and Cambrian may be related to ancestral polyplacophora. "Matthevia" is a late Cambrian polyplacophoran preserved as individual pointed valves, and sometimes considered to be a chiton. The polyplacophorans may have formed when an aberrant monoplacophoran was born with multiple centres of calcification, rather than the usual one. Selection acted on the resultant conical shells to form them to overlap into protective armour. Their original cones are homologous with the tips of the plates of modern chitons.
Sand dollar
The Sand dollars are species of flattened, burrowing sea urchins belonging to the order Clypeasteroida. "Echinarachnius parma", the Common Sand Dollar, is widespread in the Northern Hemisphere, from the intertidal zone to considerable depths. Sand dollars can be found in temperate and tropical zones, but not in Great Britain.
All sand dollars have a rigid skeleton known as a "test". This is the typical white disk found washed up on beaches. The living animals have a skin of movable spines on the test. Movement is done by the action of the spines. Like other sea urchins, sand dollars have five paired rows of pores. The pores are arranged in a petal-like pattern. These pores are perforations in the endoskeleton through which the tube feet, used in gas exchange, project from the body.
Living sand dollars have small spines covering its entire body. They are softer and much shorter than those of the sea urchin. Like all echinoderms, sand dollars have tube feet. They are not used to move around, but simply to breathe. The sand dollar's tube feet actually stick out of the top of the sand dollar. On a sand dollar test, there is usually a pattern that looks like the petals of a flower. That pattern is made up of many tiny holes, and it is through these holes that the sand dollar's tube feet came out when it was alive.
A sand dollar uses its tiny spines to move around, and to dig into the sand. It often does this to bury itself in the sand. Sometimes, a sand dollar will only partially bury itself in the sand, and ends up poking up from the sand, standing on its side.
On the underside of a sand dollar, there is a star pattern spreading out from the center where the mouth is. This star pattern is made up of that are called "food grooves". Sand dollars filter sand and water, catching plankton and other things on their spines. Then, with cilia, the spines move the food into a food groove, and the food travels down the food groove to the mouth. Its food consists of crustacean larvae, small copepods, diatoms, algae and detritus.
The sand dollars are the most specialised sea urchins. All their features are adaptations for burrowing. They live just beneath the sand, either flat or at an angle. At an angle they keep the edge facing the oncoming currents, presumably to catch food. This excellent habitat has been taken up by other groups of sea urchins. The heart urchins, another order, are even more effective in burrowing. Sand dollars can live for up to 10 years.
Most living sand dollars have dark colours, like brown or purple. Their darker color helps them stay camouflaged, easily hiding in the sand or mud or on the sea floor. The tests of sand dollars do not have bristles and tube feet, and because of the sun, they usually become white.
Hyperbolic trajectory
In astrodynamics, a hyperbolic trajectory (which is also an escape trajectory) refers to an object (such as an asteroid) which follows a path similar to a hyperbola around a central object. This motion follows Kepler's Laws. A hyperbolic trajectory occurs when the eccentricity of its orbit is greater than 1.
Other types of motion in astronomy include circular orbit, elliptical orbit, and parabolic trajectory.
Goole (disambiguation)
Goole can be any of the following:
Babcock, Wisconsin
Babcock is an unincorporated community in Wood County of the state of Wisconsin in the United States. The ZIP code of Babcock is 54413.
Green County, Wisconsin
Green County is a county that is found in the state of Wisconsin in the United States. 33,647 people live in Green County as of the 2000 census. The county seat of Green County is Monroe.
Green County has an area of 585 square miles, says the United States Census Bureau.
The following is a list of the cities, towns, villages, and unincorporated communities that are found in Green County:
Kefalonia
Kefalonia (and Kephalonia or Cephalonia) is a Greek island in the Ionian Sea. It is the largest of the Ionian islands and the sixth largest Greek island after Crete, Euboea, Lesbos, Rhodes and Chios. Its area is 781 square metres and its population is 36,404 according to a 2001 Greek census.
Kefalonia is home to the highest mountain in the Ionian islands. The mountain is named Ainos and its altitude is 1, 628 metres. The biggest town on the island is Argostoli which is the capital of the Kefalonia prefecture. The second biggest town is Lixouri which is located opposite Argostoli. Beside Kefalonia is the island Ithaca, the place of birth of ancient hero Odysseus. Some archaeologists believe that Kefalonia is the place of birth of Odysseus.
Kefalonia has many beautiful beaches and it is one of the most popular tourist destinations. The most popular beach on the island is Myrtos which is located in the north-west of the island. Kefalonia hosts a truly beautiful natural environment with many forests mainly on Ainos mountain. Also in Kefalonia there is a famous cave-lake which is named Melissani and is located in the east of the island
Tommy Lee
Tommy Lee (born October 3, 1962) is an American musician and drummer for the band Mötley Crüe. In 1999 he started a band called Methods of Mayhem. They have released two albums. He has also released two solo albums.
He was married to Pamela Anderson from 1995 until they divorced in 1998. They had two sons, Brandon and Dylan.
Billy Bishop
William Avery "Billy" Bishop (8 February 1894 – 11 September 1956) V.C. was a Canadian flying ace from World War I. He won 72 fights, making him the top Canadian flying ace.In 1919 Bishop was photographed with Canadian Ace William George Barker V.C.
2050s
The 2050s decade will begin on January 1, 2050 and will end on December 31, 2059.
Kim Mitchell
Joseph Kim Mitchell (born July 10, 1952) is a Canadian guitarist. Mitchell was the singer and guitarist for the band Max Webster and now hosts a radio show for CILQ-FM (Q107) in Toronto.
Ot en Sien
Ot en Sien (Ot and Sien) are two little children who appear in a series of stories which were written in the Dutch language more than a hundred years ago. Ot (short for “Otto”) is a little boy and Sien (pronounced like the English word “seen”), whose name may be short for “Francine”, is the little girl who lives next door. Although they are now very old-fashioned, the books are still popular in Holland. They were written in rhyme and were illustrated with colourful pictures.
The author of the stories was called Hendricus Scheepstra. The ideas for the stories were given to him by Jan Ligthart. Cornelis Jetses made the illustrations.