Just the Biofacts: Shark Egg Cases

White spotted bamboo shark
You can learn a lot about the animals in The Trust Family Foundation Shark and Ray Touch Tank from the educators working in the exhibit. And they usually bring some interesting visual aids along with them, too.

You might see one of them holding what looks like an elongated, dried out dumpling with strings trailing from it. What could it be?

Well, some sharks give birth to live young, but other sharks lay egg cases with embryos inside. The biofact (A biofact is a combination of the words artifact and biology, used to refer to preserved items such as animal bones, skins, molts and eggs.) below on the right is actually an egg case laid by a white spotted bamboo shark.

White spotted bamboo shark egg cases

White spotted bamboo sharks are a type of bottom-dwelling shark found in the Pacific Ocean from Madagascar to Indonesia and Japan. They are a type of oviparous shark, which means they lay eggs that hatch outside of the body. Once the male fertilizes the eggs, the female has the hard task of finding a safe spot to lay them.

In many sharks that lay eggs, the embryo takes several months to grow and hatch. By finding a secure hiding spot, the female can increase the embryo's chance of survival. In many places, females will find a spot around coral reefs or among the roots of mangroves. She attaches the eggs by wrapping a sticky tendril around the reef or root to help anchor the case.

Baby shark development inside casing.

The white spotted bamboo shark, as well as many other shark and fish species, rely on mangroves (learn more about mangroves on the Global Explorers Blog) as nurseries and places to rest. Without them, these animals would have a hard time raising their young.

Whitespotted bamboo sharks are listed as Near Threatened. They are hunted in India, Thailand, and China for human consumption and for traditional Asian medicines and they are also threatened by the destruction of mangrove habitat that occurs when coastal areas are developed.

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