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Black widow

Zařazeno: iReferaty.cz > Referáty > Anglicky psané referáty > Black widow
Titulek: Black widow
Datum vložení: 20.4.2009
Referát vložil: tajak


Black widow - Latrodectus mactans or 7 characteristics of life

The black widow is a very toxic spider, which lives in Australia and in North and Middle America.

How does it feed?
It makes its own web very sticky in the middle, where it usually catches flies, grasshoppers, locusts, butterflies. However, sometimes it is hunting some terrestrial insects e.g. centipedes and some types of smaller spiders. When its prey is caught in a web, it leaves its hiding place it dresses the prey into a web and biting it puts toxic in its prey and waits until it dies. Then it slowly eats it. There is one more information about feeding, but I will comment on it in reproduction.

How does it grow?
It is staying in egg for bout 20 or 30 days. It is partially independent after 3-4 months of its life, but independent of its mother it is after 6-9 months of its life. Female length is 4-5 cm with limbs. Male length is usually half of female length- 2-3cm with limbs. Female can live for about 4 years, but male’s life is much shorter, because of the reproduction.

How does it reproduce?
It does reproduction sexually. Before reproduction, female makes a substance, which attracts males from the nearest precincts. After reproduction, the female eats the male, because she needs meat, and it is why we call it the black widow. Its egg is putting into a place where they are saves from dangerous world. During one summer it can product more than 200 eggs, but usually stay alive less than 100 eggs.

How does it excrete?
Most terrestrial chelicerates cannot afford to use so much water and therefore convert nitrogenous wastes to other chemicals which can be excreted as dry matter.

How does it move?
Of course, it has eight legs like other spiders. It can move with two style-In the air its web or on a surface with its leg. It can move vertically too. When it moves vertically, it uses its microscopic “hooks” on its feet and that microscopic hooks are so small that on the most of the surfaces they can catch the surface. On extremely unruffled surface like glass, it uses small sticky “hairs”, which can stick on any surface.

And what about irritability?
It is not aggressive, but when it feels dangerous, it can bite the dangerous thing. It has some poison in its teeth. Some scientists even think that female’s (males are smaller and so the result of the poison) poison could be stronger than that of a rattlesnake or cobra’s poison. However, even though a female is small, it can kill even a human being. The male’s poison does not have so big result, but its bite could be dangerous for old people and for children.

How does it breathe?
It breathes in with its mouth. The air gets into tracheas - “pipes” where the air doesn’t move in a liquid, it moves just like a gas in that “pipes”. The most of the “pipes” are in its bum. Then the air goes by the same way out of the black widow’s body. There is one more type of breathing which the black widow uses and then the air goes to a so called book lung and the hemolymph (special liquid) distributes the air along the body.

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