Two subclasses of cestodes are differentiated on the basis of the numbers of larval hooks, the Cestodaria being decacanth (10 hooks) and the Eucestoda being hexacanth (6 hooks). Collectively, 14 orders of cestodes have been identified according to differences in parasite morphology and developmental cycles.
Most meteorites originate between Mars and Jupiter, where a belt of asteroids has lingered for 4.5 billion years, since the solar system was young. No rock on Earth is as old as a meteoriteâall terrestrial material has been ground, melted, and reformed by plate tectonics. Meteorites have other, less common, origins. Meteor impacts on the moon or Mars can eject surface material into space that ends up on Earth. Last year a 10.5-ounce meteorite that originated on Mars fetched $94,000. A 4-pound lunar meteorite, the most expensive ever auctioned, sold for $330,000 in 2012.
D. The surface of Mars E. Meteorites and most asteroids 24) A meteorite is: A. A chunk of space debris that has struck the ground. B. A streak of light in the atmosphere. C. An icy body with a long tail extending from it. D. A chunk of space debris orbiting the Earth. E. An irregularly shaped body, mostly found orbiting between Mars and Jupiter. 25) Objects in the Kuiper belt: A. Are in random orbits at all inclinations to the ecliptic. B. Lie beyond the orbit of Neptune, and close to the ecliptic. C. Are the sources of long-period comets. D.