37 The Mermaid's Purse-Low

The Mermaid's Purse FOCUS Question How does an egg case help a young shark?

美人鱼的钱包焦点问题一个鸡蛋案如何帮助一条小鲨鱼?

What Is That? Sam and her father walked along the beach. They came across a pile of seaweed. It was up near the dunes. Sam turned the pile over with a stick. She saw a few shells on the sand. Then she spotted something strange. It was shaped like a rectangle. But it had hooks on the corners. "What is that?" Sam asked her father. "Nice find! That's a mermaid's purse," Dad said. "It's an egg case from a shark."

那是什么?萨姆和她的父亲沿着海滩散步。 他们发现了一堆海藻。 它在沙丘附近。萨姆用棍子把那堆东西翻过来。 她看到沙滩上有一些贝壳。 然后她发现了一些奇怪的东西。 它的形状像一个矩形。 但它的角上有钩子。 “那是什么?”萨姆问她父亲。 “好找!那是美人鱼的钱包，”爸爸说。 “这是鲨鱼的蛋案。”

A Different Kind of Fish There are over four hundred kinds of sharks in our oceans. Sharks are a kind of fish. Their skin is covered with special scales. Shark skin feels rough, like sandpaper. Most fish have skeletons made of bone. But a shark's skeleton is made of a material called cartilage. It is softer and more flexible than bone. Your outer ears are made of cartilage. Sharks live in every ocean on Earth, They hunt for fish and other sea animals.

一种不同的鱼在我们的海洋里有四百多种鲨鱼。 鲨鱼是一种鱼。 它们的皮肤上覆盖着特殊的鳞片。 鲨鱼皮摸起来粗糙，像砂纸一样。 大多数鱼的骨骼都是由骨头组成的。 但是鲨鱼的骨骼是由一种叫做软骨的物质组成的。 它比骨头更柔软，更有弹性。 你的外耳是由软骨组成的。 鲨鱼生活在地球上的每一个海洋里，它们捕食鱼和其他海洋动物。

Sharks, Skates, and Rays Most sharks have long, thin bodies. They swim by moving their strong tails. The biggest fish on Earth is the whale shark. It is longer than a school bus. The smallest sharks are only as big as a shoe! Skates and rays are closely related to sharks, but they look different. Their bodies are flat and shaped like kites. They swim by moving their wing-shaped fins up and down. Some rays have points on their tails. In stingrays, this point has venom in it.

鲨鱼、鳐鱼和鳐鱼大多数鲨鱼的身体又长又瘦。 它们靠摆动结实的尾巴游泳。 地球上最大的鱼是鲸鲨。 它比校车还长。 最小的鲨鱼也只有鞋子那么大!鳐鱼和鳐鱼与鲨鱼密切相关，但它们看起来不同。 它们的身体扁平，形状像风筝。 它们通过上下移动翅膀形状的鳍来游泳。 有些鳐鱼的尾巴上有尖。 在黄貂鱼身上，这个点有毒液。

Being Born Many sharks and rays give birth to live young. The eggs hatch inside the mother's body. The babies are born ready to swim. They look like their parents only smaller. They hunt as soon as they are born. Other sharks and some rays lay eggs. Skates also lay eggs. These eggs are different from other fish eggs. The babies grow inside a tough egg case. Do You Know? Newborn sharks are called pups!

许多鲨鱼和鳐鱼产下幼崽。 卵在母体内孵化。 小海豚一出生就会游泳了。 他们看起来像他们的父母，只是更小。 他们一出生就开始打猎。 其他鲨鱼和一些鳐鱼产卵。 冰鞋也产卵。这些鱼卵与其他鱼卵不同。 幼崽在一个坚硬的卵箱里生长。 你知道吗?新生的鲨鱼被称为幼鲨!

The Mermaid's Purse The egg cases of sharks, skates, and rays are not shaped like other eggs. Some are long and flat (see cover.) Many have long hooks on the ends. The hooks catch on seaweed or rocks. They keep the egg in one place. The case hides the egg from animals that might eat it. The hooks look like the straps on a purse. For this reason, the egg case of a shark, skate, or ray is sometimes called a "mermaid's purse." One shark has an egg case shaped like a screw. The mother shark lays the eggs between underwater rocks. The screw shape of the egg case helps secure it between rocks or coral.

鲨鱼、鳐鱼和鳐鱼的蛋盒形状与其他蛋不同。 有些是长而平的(见封面)。许多在末端有长钩。 钩子可以钩住海草或岩石。 它们把蛋放在一个地方。 这个箱子隐藏了鸡蛋，不让动物吃掉。 钩子看起来像钱包的带子。 因此，鲨鱼、鳐鱼或鳐鱼的卵箱有时被称为“美人鱼的钱包”。 其中一条鲨鱼的卵箱形状像螺丝钉。 鲨鱼妈妈在水下的岩石之间产卵。 螺丝形状的蛋盒有助于将它固定在岩石或珊瑚之间。