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How long does it take for a swell shark egg to hatch? How big will the swell shark be and how does it know how to survive?
Question Date: 2002-04-24
Answer 1:

Swell sharks are pretty neat animals. They live in shallow water all along the Pacific coast, from Monterey Bay, California to the country of Chile, south of the equator in South America.

Swell sharks lay 2 egg cases at a time which sit in kelp beds, where they are protected and well camouflaged (hard to see) until they hatch.

The time it takes for swell shark egg cases to hatch ranges from 7.5 to 10 months. The exact time depends on the temperature of the ocean water where the egg cases sit. Egg cases take less time to hatch in warmer water. Sharks are cold-blooded, which means the baby sharks in the egg cases have the same body temperature as their environment. In general, growth is faster at higher temperatures.

When the shark egg cases hatch, the baby swell sharks will be only a few inches long. Adult swell sharks do not get much bigger than 3 or 4 feet, which is small for a shark. Because the baby swell sharks are so small, they are easy prey for a lot of marine animals. If we don't tie the lids onto the aquariums at UCSB, even raccoons will eat the baby swell sharks. It's hard to say how any baby animal "knows" how to survive since we can't ask them, but I think most scientists would agree that it is by instinct. Behaviors that come from instinct are not learned by, are known by the animal even before it is born. For example, human babies cry when they are upset even on their first day in the hospital, and this is purely by instinct.

Swell sharks feed at night and adults hide during the day and remain motionless so that they are harder to see. This behavior is by instinct and is probably the main way that baby (and adult) swell sharks survive. Another thing that helps them survive is their coloring, which allows them to blend in with the kelp and makes them hard to see unless they move.

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