The Shark Gallery - Learn all about Sharks, including their Prehistoric Relatives and Fossil Shark Teeth
Quick Facts about Sharks
Sharks don't have bones! Instead, they have Cartilage.
Cartilage is firm but more flexible than bone. It is found in your nose and ears.
Fish that are made of Cartilage are called "chondrichthyes." This class of fish include Sharks, Skates, Rays, and Chimaeras.
Many Types of Sharks:
Sharks and Rays belong to the Elasmobranchii subclass.
This subclass contains 8 extant (living) orders, which contains over 600 species.
Over 400 of those species are sharks! Of the 400 species of sharks, how many can you name?
Sharks are Ancient:
Sharks first appear around 450 million years ago in the Ordovician time period.
Some of the very first shark fossils come from the Harding sandstone in Colorado.
The first sharks may not have had teeth or even jaws!
Here is an article about Shark Evolution.
The Largest Shark:
The largest shark is the Whale Shark. Whale sharks can reach lengths over 40 feet!
Don't worry, they are filter feeders, which means they eat mainly plankton, tiny fish, jellyfish, and shrimp.
The Largest Prehistoric Shark:
The largest prehistoric shark is called the Megalodon. Megalodon was like a GIANT Great White shark.
It could probably reach sizes over 60 feet in length, and ate whales
Luckily it wen't extinct around 2.5 million years ago!
Here is an article all about the Megalodon Shark
Sharks are unique in that they have rows of replacement teeth growing behind each tooth. When one falls out, another one simply replaces it.
A shark can go through 10,000 to 20,000 teeth in its lifetime!
Sharks have adapted to a wide range of conditions. Some live in tropical waters, others live in arctic waters. Some live near-shore, while others live in the open ocean. Some prefer very deep water, others prefer shallow water.
Some sharks, like the Bull shark and the River shark can even tolerate freshwater!
Sharks also come in a wide variety of shapes and sizes.
Most sharks are under 3 feet in length.
However, some sharks are quite large. The Basking shark can reach lengths of over 30 feet, while the Whale shark can reach lengths of over 40 feet!
Sense of Smell:
The Great White shark can smell a single drop of blood in an olympic sized pool!
Conservation Status: Although the total numbers of sharks are unclear, many sharks are threatened by overfishing and shark finning.
According to the IUCN, 25% of all shark and ray species are threatened with extinction.
110 species are listed as threatened and another 95 species are listed as near threatened.
Althought the media wants you think otherwise, shark attacks are rare! Humans are not a food source for sharks, even the Great White.
Your chances of getting killed by a vending machine is higher than getting killed by a shark...Consider the following:
On average there are less than 100 shark attacks per year. Of those, less than 10 are fatal.
When at the beach, your chances of being attacked by a shark are a mere 1 in 11.5 million.
To give you a perspective, here are some other averages:
There is less than 1 fatal shark attack each year.
Vending machines kill 2 people per year.
Icicles kill 15 people per year.
Horses kill 20 people per year.
Cows kill 20 people per year.
Lightning kills 49 people per year.
Deer kill 130 people per year.
700 people accidentally drown each year.
Texting while driving kills 3,000 people per year.
Jellyfish kill 15 times more people per year than sharks.
Champagne corks kill 24 people per year.
Coconuts kill 150 people per year.
Elephants kill 500 people per year.
Hippos kill 3,000 people per year.
Snakes kill around 50,000 people per year!
Shark Anatomy - What do Sharks look like?
Sharks are fish that are in the Chondrichthyes class, 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.
Figure 1: This shark picture shows the main body features of a shark. This picture was taken at Wolf Island, in the Galapagos during one of my dive trips.
Figure 2: This shark picture shows detailed structures on the head of a shark, plus claspers, which are not present in the first picture. This picture was taken at the North Shore in Hawaii during a shark cage excursion. (note: the spiracle in this image is actually closer to the eye. I need to fix the diagram)
Note that each shark order has a slightly different anatomy. Some orders have fin spines, while others don't. Some have one dorsal fin,
while other orders have two. The number of gill slits ranges from 5 to 7 depending on the order, etc...
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.
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.
Recommended Books and Educational Kits about Sharks
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!
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.
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!
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.
This is a nice article on shark origins and evolution. Where they came from and how they changed overtime.
This is an article on all the different types of shark fossils you can find. There's more than teeth!
An article on why fossil shark teeth, and fossils in general, come in a plethora of colors!
Browse the Fossil and Modern Shark Genera and learn all about each type of shark, from the shark biology, anatomy, and ecology, to fossil shark teeth, and fossil hunting locations of the prehistoric sharks.
Each link has information about the prehistoric or modern shark, diagrams, terminology, sample fossils, fossil hunting locations, past fossil hunting trips, and more.
Either use the dropdown menus to select the shark genera/common name or scroll down and browse.