Answer:
1 ). Earthworms have what are called closed circulatory systems. Closed circulatory systems are those in which the blood is kept in a closed system of vessels, like in humans. Open circulatory systems are when the blood is pumped into a body cavity called a hemocoel, allowing the blood to surround the organs.
2). Crayfish also have an open circulatory system. Blood flows into the heart through dorsal ostia, and is pumped into body sinuses through arteries at both the posterior and anterior ends of the ventricle.
Explanation:
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Primary source.............................
Answer:
Secondary succession.
Explanation:
Clearcutting leaves an area barren. It is a horrible practice and is opposed by every environmental group. There are better ways of logging without destroying the plant life present there. This is secondary succession because plant life did exist in the area that clear cut and will again if the logging company or the government will replant the area.
Answer:
Do you mean planets?
if so,The heavy rocky particles within the inner part of the disk formed planetesimals and eventually, inner planets. In our solar system, the four innermost planets Mercury, Venus, Earth and Mars are known as inner planets. They lie inside the asteroid belt. They have volcanoes and valleys and are very hot compared to outer planets.Inner planets are much smaller than the outer planets, and are rocky with an iron core.
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