There are many types of crabs in the sea. most of them have shells made from chitin, which is different from calcium carbonate (it's actually the same stuff that your fingernails are made of). however, hermit crabs live in shells that are made from calcium carbonate. where do these "houses" come from? do the crabs make them?

Which of the following is an example of competition a. the leaves of a tree prevent a small shrub from getting sunlight. three species of birds feed a different heights in the same tree. b. three species of birds feed at different heights in the same tree c. zebra and giraffe’s feed on different grassland plants d. cats living in two different homes eat the same brand of cat food.