Sharks are a group of elasmobranch fish characterized by a cartilaginous skeleton, five to seven gill slits on the sides of the head, and pectoral fins that are not fused to the head. Modern sharks are classified within the clade Selachimorpha (or Selachii) and are the sister group to the rays. However, the term "shark" has also been used for extinct members of the subclass Elasmobranchii outside the Selachimorpha, such as Cladoselache and Xenacanthus, as well as other Chondrichthyes such as the holocephalid eugenedontidans.
Add an image or video to this topic
No signin required
More of the best postsLoading . . .
It may be a case of "Occam's razor" where the simplest answer is best. There are more people in the water. Global shark populations have actually been experiencing a sharp decline over the past few decades with some estimates suggesting we could be losing 100 million sharks each year! Other factors include low rainfall along the coast that has made the water more salty which both sharks and their prey like and also certain species of shark become agitated above a certain temperature (80 degrees Fahrenheit) and warmer waters are altering their behavior.
Contributed by Sam Feldstone
What is Sussle?
Sussle is the first, open visual encyclopedia. Anyone can use it.
What's a visual encylopedia?
It has beautiful images and viral videos that are way more fun than reading all the text in traditional encyclopedias.
5 reasons you should add your own images and videos:
- If you found Sussle interesting, then give back by adding something interesting for others.
- Help others learn in a fun way.
- Make someone else interested in this topic laugh or say wow!
- Become internet-famous as people like and share your post.
- It's super easy, so it won't take more than a minute.
Ready to start?
Just click on the red module above.