He was also the first President to be impeached in 1868, but was later acquitted in the Senate. When a president is removed by Congress, the House of Representatives must vote to impeach him, and then the Senate to convict, by a 2/3-majority. Although the Republicans had that many senators, the conviction failed by one vote. Several Republicans thought it was not their job to replace the president, and that the charges against Johnson were made up. So Johnson could keep his job for the last year. There would be another 130 years before another president was impeached, Bill Clinton in 1998. Johnson was the only U.S. president never to have gone to school, and was taught to read by himself and by his wife, Eliza McCardle Johnson. He also taught himself law and politics by reading himself. The U.S. purchased Alaska from Russia for $7.2 million (the price was 2 cents per acre) while he was president, but it was Secretary of State William Seward who arranged the buy. It is now considered a very wise move and the natural resources in Alaska today are worth many billions.
After his term ran out, Johnson left Washington. In 1875, he returned after being again elected senator for Tennessee. He died the same year. He remains the only president of the U.S. to have served as a senator after being president. One former president, John Quincy Adams, has served in the House of Representatives after his presidency, however.
1808
1808 was a leap year starting on Friday of the Gregorian calendar.
Starfish
Starfish, or sea stars, are Echinoderms of the Class Asteroidea.
All live in the ocean, on the sea floor. Many starfish live in deep water, others in shallow water. Some live in the intertidal zone, between low and high tide. They have five or more arms and can be quite large. The Sunflower sea star ("Pycnopodia helianthoides") is the largest: fully grown, its arm-span is about a metre. This is a bit larger than the famous Crown-of-thorns starfish, which lives on coral polyps.
Although starfish are invertebrates, they do have a kind of skeleton. The bodies of starfish are composed of calcium carbonate plates, known as 'ossicles'. These form the endoskeleton, which takes on a variety of forms such as spines and granules.
They have a primitive nervous system, but not a brain. They also do not have blood, instead they use sea water to pump things around their bodies.
There are over 1500 different species of sea star. Most sea stars are predators. They eat mussels, clams, and other bivalves. Occasionally, they catch small fish.
Most starfish have five arms, called "rays" that come out from a center circle (disk). If a starfish has more than five rays, it will often have rays in multiples of five; there could be 10, 15, 20, or even 30 rays on one starfish. This is called pentameral (five-fold) symmetry.
The degree of protection offered by the skeleton differs between species. If the skeleton becomes more rigid, it offers better protection against predators. However, this will tend to limit its feeding alternatives. Great flexibility is required for the process of external digestion used by many species to eat bivalves. The less well armoured species may adopt a life in places where they are not so open to predation. The heavily armoured ones can tough it out in the most competitive habitats:
The movement of starfish is guided by their senses of touch and sight. There are five 'eyes', light-sensitive cushions, one at the end of each arm. These and the tube feet are connected to nerve fibres, so these animals are more complex than might appear.
Although starfish started off as filter-feeders, they evolved to become major predators of shell-fish (the brachiopods and bivalves). They can also eat small crustacea and fish. Their tube feet developed suckers, perhaps originally to improve movement. Later, they were used to open shell-fish.
The shells of brachiopods and bivalves are held together by strong muscles. What the starfish does is clamp hold of them on either side with its tube feet, and apply a steady pull. The starfish, with its muscles and hydraulic system, can pull for much longer than any bivalve muscle can withstand. Apparently, ten minutes are usually enough to open the shell a bit. Then the starfish slips its stomach inside the shell. The stomach can get through a slot as narrow as 0.1mm. The starfish then dissolves the mollusc where it lives, absorbing the nutrients. This digestion process takes much longer than opening the shell, perhaps a couple of days.
Some species swallow the shell whole, and dissolve the contents inside their stomach, then push out the shell afterwards.
The ability of starfish to eat brachipods and bivalves developed in the Mesozoic, especially in the Jurassic and Cretaceous. This was part of the "Mesozoic marine revolution", which transformed the sea-floor fauna. Weakly defended and static shellfish disappeared, and more heavily armoured or more mobile shellfish flourished.
Starfish, like many sea creatures, are able to "regenerate" (grow back) parts of their bodies. Starfish are better at regeneration than most other creatures. Not only can a new ray grow when a ray is torn off, but if the torn off ray has even a small piece of the central disk still attached, a whole new starfish can grow from the one ray.
Because starfish like to eat clams and oysters, fishermen who gather shellfish have tried for years to get rid of them. To kill the starfish, fishermen would catch them, slice them right in half, and throw them back in the ocean. However, because starfish can grow back parts of their bodies, they were actually increasing the number of starfish.
1582
Jellyfish
Jellyfish are animals of the phylum Cnidaria. They are a monophyletic clade, the Medusozoa. Most of them live in the oceans, in salt water, where they eat small sea animals like plankton and little fish, and float in the sea. Only a few jellyfish live in fresh water.
They have soft bodies and long, stinging, venomous tentacles that they use to catch their prey, usually small plankton animals or small crustaceans or tiny fish. Some jellyfish hunt others by stinging cells called "nematocysts". A jellyfish is 97% water.
Most jellyfish have a bell-shaped body and long tentacles at the underside of the body. Tentacles are long "arms" with special stinging cells called nematocysts. They move by contracting their bodies, but they do not have much control over where they go: most of the time, they drift with the water current. The largest type of jellyfish is the Lion's mane jellyfish, which has tentacles that can be as long as 60 meters, but most jellyfish are much smaller.
The Medusozoa are four classes of the Cnidaria:
There are many types of jellyfish. The smallest jellyfish are just a few centimetres across. The largest jellyfish is the Lion's mane ("Cyanea capillata"), whose body can be over 3 feet (1 m) across, with much longer tentacles. Some jellyfish glow in the dark (this is called phosphorescence). Some of the most dangerous jelly fish include the box jelly (Genuses "Chironex", "Chiropsalmus" and "Carybdea") and the tiny, two-cm-across Irukandji jelly ("Carukia barnesi"); the venomous sting of these jellyfish can kill a person.
Many animals eat jellyfish, including sea turtles and some fish (including the sun fish). Humans eat jellyfish too; especially in Asia jellyfish are considered a delicacy. Jellyfish spoil very quickly after they are caught. Sometimes they are dried to preserve them. There is a different process in which they are cleaned, which can take up to 40 days. They are often eaten in a kind of salad, with soy sauce or vinegar.