The Great Shark Egg Case Hunt by Kasey Whitelaw illustrated by Sylvia Morris

Understanding how many sharks reproduce helps scientists and conservationists protect vulnerable species. Since sharks generally have fewer offspring than other fish, overfishing can severely reduce populations. The fact that only a few sharks lay eggs means each egg is important for the species' survival. (How Stuff Works)

Begin with the title:

• Great - in this book you will meet children from all around the world (that's pretty great).
• Shark - in Australia we are fascinated by sharks - very sadly in my local area just a couple of weeks ago a popular local resident lost his life after a shark attack. Of course not all sharks are dangerous.
• Egg case - wait a minute - do sharks lay eggs? Yes, and that is the topic of this book.
• Hunt - why are people hunting for these eggs? Is that okay? What will happen to the information? This sounds like a Citizen Science project.

Image Source: A to Z animals

Each shark produces a slightly different mermaid’s purse, so it’s possible to identify the original shark species just from this casing. Rays, chimeras, and skates also create egg cases similar in appearance to a shark casing. These are also colloquially known as a mermaid’s purse.

In this video from 2023 a CSIRO scientist explains the Citizen Science project in more detail. 

As with all good nonfiction this book will give your students (and you too) a terrific jumping off point for further investigations and research.

If I was sharing this book in a classroom or with a library group I would grab a large sized world map perhaps with more details than the one in the book (paper not on a screen) and then print out images of eight sharks from around the world to add to the map then after reading The Great Shark Egg Case Hunt I would assign groups of students to research each shark and then present a brief talk to the class using the map and the shark photo plus a photo of the egg case as props for their talk. At the end of the week when every group has presented their findings the kids could write a 3-question quiz for their classmates to see how well everyone was listening and also to discover which curious facts really grabbed everyone's attention. This book is aimed at a younger audience ages 5-9 but this was a topic I knew nothing about so even as an adult I enjoyed exploring this topic more deeply. 

Here are a few of the things I discovered from this book and from further reading:

• Puffadder Shysharks from South Africa curl up into a doughnut shape to avoid predators.
• Here's a new word - chimaera. They are also known as ghost sharks, rat fish, spook fish and rabbit fish. The Elephant Fish from New Zealand is a chimaera and this is the shark in this book. 
• Chimaera are closely related to sharks, skates and rays. But they diverged from their shark relatives around 400 million years ago.
• In Alaska there are jelly fish called Moon Jellies
• A mermaid’s purse is an empty shark egg case that washes up on shore. It looks a lot like seaweed when it is on the beach.
• This book, The Great Shark Egg Case Hunt, focuses on Oviparous Sharks: Egg-Laying Specialists but there are also Viviparous Sharks: The Live-Bearers and more sharks with more complex reproductive processes.
• Primarily slow-moving, bottom-dwelling fishes of the oceans, the skates and rays are close relatives of the sharks. All three belong to the same class of fish, Chondrichthyes—vertebrates whose skeleton is composed of cartilage, not true bone. (Source)

Image Source: A to Z animals

Bullhead sharks, Port Jackson sharks, and horn sharks are sharks that produce spiraled eggs

Huge thanks to CSIRO Publishing for this advance copy - The Great Shark Egg Case Hunt was published last week. 

Do Sharks Lay Eggs?

Around 25% of all sharks lay eggs. Most sharks do not lay eggs and instead give birth to live young that have developed inside the mother’s body. The eggs of oviparous (egg-laying) sharks are encased in leathery pouches known as “mermaid’s purses”, which protect the embryo as it develops. Some shark species spend over a year in the egg-case before hatching.

Shark egg-cases are generally rectangular in shape with a horn projecting from each corner. Some have long, string-like tendrils extending from the horns. The tendrils help to secure the egg-case to vegetation on the seabed.

The Great Eggcase Hunt is an initiative of UK-based charity The Shark Trust. It began in the UK 20 years ago and has since recorded more than 380,000 individual egg cases from around the world. Australian Geographic

There are at least 37 species of sharks and skate that lay eggs of many shapes and sizes to be found on Australian beaches. Here is a link to the detailed teachers notes. There is also a lot of good advice in this book - "look don't touch".

I found one list that identified nine types of sharks: Mackerel sharks; Ground sharks; Bullhead sharks; Carpet sharks; Angel sharks; Saw sharks; Frilled and cow sharks; Dogfish, lantern sharks and sleeper sharks and Bramble sharks. But then in The Great Shark Egg Case Hunt I read (in the back notes) about the Hornshark; the skate; and the catshark so clearly there is a lot more to discover.

What Are Some Sharks That Lay Eggs? (Also Called Oviparity) These sharks are oviparous:

• Cat Sharks
• Horn Sharks
• Bamboo Sharks
• Carpet Sharks
• Zebra Sharks
• Swell Sharks
• Port Jackson Shark
• Dogfish Sharks
• Australian Swellshark

Kasey Whitelaw is a marine biologist, educator and children’s writer. She has an interest in connecting children to science and nature, sparking their wonder and curiosity through storytelling and education.

Sylvia Morris is an illustrator and science enthusiast. She loves illustrating picture books because it combines two of her favourite activities: reading and problem solving. She is also the illustrator of Bear to the Rescue and The Opal Dinosaur.