15 facts about lobsters

1. Lobsters (Nephropidae) are ocean-living shellfish which look like large crayfish.
2. Lobster's industry nets more than US$1 billion annually.
3. A lobster has ten jointed legs, the first pair bearing great, clamp-like claws.
4. They are invertebrate arthropods, with a strong protective exoskeleton.
5. Most lobsters are dark green, becoming red only when cooked.
6. They are appreciated for their flavor and texture.
7. Besides their two long antennae, they have a pair of eyes set on short stalks. Their jointed abdomens are tipped by a set of bladed tail plates used in swimming.
8. Lobsters, like snails and spiders, have blue blood due to the presence of haemocyanin, which contains copper.
9. Lobsters live in the coastal waters of the Atlantic and Pacific oceans.
10. Full-grown lobsters are nearly two feet (60 cm) in length and weigh 25 pounds (11 kg).
11. A mature female may lay thousands of eggs at a time. They are carried on her abdominal gill organs until early the following spring. Then the hatching larvae come free and float on the ocean while feeding on plankton. When the larvae are one inch long, they descend to the ocean bottom and start life as young adult lobsters.
12. Older lobsters are more fertile than younger lobsters. 
13. Like all arthropods, lobsters must shed their hard exoskeletons periodically in order to grow. 
14. Lobster's right and left claws may be of unequal size. 
15. According to the Guinness World Records, the largest lobster was captured in Nova Scotia, Canada, and weighed 44.4 lb.

Where does chalk come from?

Where does chalk come from?

Countless billions of tiny animals too small to be seen without a microscope live in the sea. Some of them have the long name of foraminifera. Under a microscope these tiny animals look like jewels. Each one has a shell which it has made for itself.

There are diferent kinds of foraminifera. They do not all make their shells of the same material. But a great many of them make their shells out of lime from the water. When these animals die, their shells are left behind and fall to the bottom of the water.

These little animals have lived on the Earth for many millions of years. In some places long ago they lived in such numbers that their shells made a layer hundred of feet thick on the floor of the sea. Then the bottom of the sea became dry land. The layer of shells became a layer of white rock. This white rock is a kind of limestone that we call chalk.

The famous white cliffs at Dover in England are made of chalk. There are layers of chalk in Kansas and other parts of the United States that are far away from the sea.

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