"A food chain is a linear sequence of organisms through which nutrients and energy pass as one organism eats another. ... Food webs consist of many interconnected food chains and are more realistic representation of consumption relationships in ecosystems."
Answer:
Kidneys, ureters and bladder
A theory of evolution that states that a species evolves in spurts of rapid change and then goes through periods of no change is known as <span>punctuated equilibrium.</span>
Their bodies taper to points at both the snout and the tail, reducing water resistance. Also decreasing drag -- and therefore noise -- are dermal denticles, sharp scales that cover the skin of most shark species. Rather than bone, sharks have cartilage, which is much lighter and more flexible. In addition, their livers produce squalene, a fatty oil that helps them remain afloat. Their pectoral fins allow them to quickly change direction, dive and swim upward.
http://animals.mom.me/unique-adaptations-sharks-survive-7845.html
