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This is a Hammerhead Shark from my dive trip in the Galapagos. I had to hold my breath to take this close-up shot, as these hammerheads tend to shy away from the bubbles coming from scubadivers.

Shark Anatomy - What do Sharks look like?

Sharks are a type of fish in the Chondrichthyes class, or the cartilaginous fish. This means sharks do not have a hard skeleton like us, instead their skeleton is made of a dense cartilage; similar to what the tip of your nose and ears are made of.

The chondrichthyes class not only includes sharks, but also skates, rays, and chimaeras as they also have a cartilaginous skeleton.

Specifically, sharks, skates, and rays belong to the Elasmobranchii subclass. This subclass contains 8 extant orders, which in itself contains over 600 species. The following shark pictures show the physical characteristics of a shark.

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Each shark order has a slightly different anatomy. Some orders have fin spines, some have one dorsal fin while other orders have two. The number of gill slits ranges from 5 to 7 depending on the order, some are torpedo shaped, some a very flat. There are a wide range of shapes and sizes of sharks.

Most of the terminology in the diagrams are self explanatory. Some shark terms that may be unfamiliar include the spiracles and the claspers. Claspers are found on male sharks. They are used to hold onto the female while mating (Hey, they don't have hands!). The spiracles are a bit more complicated. A spiracle is a hole behind the eye that leads to the mouth. When tracing the evolution, it use to be a gill in jawless fish. When jaws developed, the jaw bones isolated this gill slit from the rest, and could no longer be used. A remnant hole from this unused gill still remains in sharks. It's kind of like a tail bone on a person, we don't have a tail but still have a little bone there.

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What is Shark Skin made of? Dermal Denticles

If you have ever touched shark skin, you have noticed it is quite different from other fish. When rubbing in one direction, it feels silky smooth. However, when rubbing in the opposite direction, it feels like coarse sandpaper! Some ancient cultures actuallly used shark skin as sand paper.

This sand paper like texture results from the sharks highly modified scales, called denticles. These denticles are very different from regular fish scales. They are very streamlined (hydrodynamic), and point away from the front of the shark. This lets water easily pass over the shark, allowing it to swim more efficiently.

Shark dermal denticles are very small, less than a millimeter in size. The images shows zoomed in sections on the tail of a shark, once zoomed in enough, you can start to see the denticles. They look like tiny diamonds, with small ridges on them.

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Recommended Shark Books, Educational Kits and Fossils

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Sharks: Ancient Predators in a Modern Sea
By: Salvador Jorgensen, 2013
Jorgenson, a top shark researcher, has done an outstanding job on this book. It is filled with incredible photos, diagrams, and latest discoveries. The writing is clear and concise. He also explains many of they scientific concepts in an easy to follow and lively writing. The book is incredibly indepth. I recommend this book for someone with a casual interest, to the serious adult. This book is it. Just check out the sample images and user reviews!

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Sharks and People: Exploring Our Relationship with the Most Feared Fish in the Sea
By: Thomas P. Peschak, 2013
Sharks and People is written by Peschak, an acclaimed wildlife photographer, who has spent many years photographing sharks. As a result, this book is a work of art. It contains many stunning images of sharks. The book does a wonderful job at examining the conservation issues and the complex relationship between sharks and people from a number of perspectives. It will change how you think about sharks.

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Sharks of the World (Princeton Field Guides)
By: Leonard Compagno et al, 2005
If you are into sharks and don't have a book by Compagno, you are missing out! He is the one that cataloged the sharks for the FAO species catalogue.

He is very thourough and not overly technical, which is a rarity! This book has full over 400 accurate and full color illustrations of all the known shark species plus a bunch on undescribed ones. The illustrations are done by Mark Dando, which is probably the best shark artist out there.

It also goes over shark biology, life history, and shark/human interactions. It's should be the main reference for anyone interested in sharks.

There is now an update to this book: Sharks of the World: A Fully Illustrated Guide , 2013. It's a hard cover, updated, and beefed up version of the 2005 book. It's a little pricier, but worth it!

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Shark Set
This kit is from Two Guys Fossils. They are one of the original fossil dealers on the internet and concentrate on quality. This is the best "Shark Kit" I've seen. It not only has shark teeth, a shark model, but also a shark jaw. Usually shark kits just have a model and a single tooth! This kit also comes with a introduction to the Great White Shark, a Geologic Time Chart & Brochure "What Is A Fossil". All Shark teeth, including the larger Otodus come with identification, including location and age.
It's a great kit for educators and kids learning about sharks.

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Shark Teeth T-Shirt by EncycloArt

This is an awesome fossil shark teeth shirt for anyone who collects shark teeth! They have a few sizes, styles, and colors.

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High Quality Shark Teeth by Fossilera

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