Saturday, September 22, 2007
Every organism’s main purpose in life is to maintain its own life. That usually means sleeping, eating and pooping. Once all those needs are satisfied, next comes the urge to reproduce. At Shark Lagoon, the sharks must be happy because they lay tons of eggs and reproduce like mad. On a typical morning, the aquarist staff finds anywhere from 5 to 20 eggs left from the night before. Some are fertilized but others are not. The fertilized ones are kept in water and quickly moved to the nursery where they can hatch. The duds are discarded.
How do you know if an egg is fertilized or not? You can’t because when they are first laid, the embryo is microscopic. The best you can do is discard the ones you know are unfertilized or do not have a chance of producing a baby. This is done by putting the egg up to a light to determine if the yolk is intact. Some eggs have no yolk or have broken yolks which cannot yield a baby. Many eggs are eaten by other sharks after they are laid. Sometimes, we may not have a fertile male in the exhibit to fertilize the eggs and in this case, all the eggs are going to be unfertilized. In all the above cases, the egg is discarded. However, if we find an egg with an intact yolk produced by a harem of both male and female sharks, the egg is moved to the nursery where hopefully, it will hatch in about three months. For oviparous animals, which means egg laying animals as opposed to animals that give live birth like humans, the offspring do not get their nutrition from mom like humans do. Instead, the baby has a yolk sac attached from which it can get its nutrients. This is why it is important that the yolk be intact for the baby to develop. When baby sharks are born, they are like miniature adults, ready to hunt. We feed them a variety of food that is small enough to fit in their tiny mouths.
With the fertilized shark eggs, it is important that they receive a fair amount of water flow. Baby sharks need to breath. Oxygen naturally diffuses into the egg from the water but the ambient water needs to be saturated with oxygen for this to occur. So where do we put the eggs? In the sump of course! Where else can you get plenty of water flow? The sump is a container who’s job is to collect the water from the aquarium to be cleaned by the filtration system and to store excess water. Typically, water flows out of an exhibit from an overflow apparatus, travels down a tube and into the sump. Therefore, all the water from an exhibit must pass through a sump which is what gives sumps such immense amounts of waterflow.
Unfortunately for the parents, the process of mating can be rough because the male needs to hold onto the female and the only way he can do that is with his tooth-filled mouth. Needless to say, some of the sharks look like they have been chewed upon. Many of our sharks have circular shaped scars on their fins as a result of the mating process. However, female sharks have much thicker skin than their male counterparts and they also heal really fast. These feminine features allow the process of mating to be a little easier on the female sharks. A few boo-boos are a small price to pay for creating the next generation and besides, baby sharks are so cute!
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