The most well known is the great white shark, thanks to the 1975 movie Jaws. However they are still a very small subsection of the over 400 shark species that have been discovered by humans so far.
9th July 2020
•Sharks have special electroreceptor organs. Sharks have small black spots near the nose, eyes, and mouth. These spots are the ampullae of Lorenzini – special electroreceptor organs that allow the shark to sense electromagnetic fields and temperature shifts in the ocean.
The first sharks appeared in the oceans over 440 million years ago. There are Around 440 Known Species of Sharks!... yes I know these numbers are the same.
•Sharks can go into a trance. When you flip a shark upside down they go into a trance like state called tonic immobility. This is the reason why you often see sawfish flipped over when our scientists are working on them in the water.
The science: 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.
• Shark skin feels similar to sandpaper. Shark skin feels exactly like sandpaper because it is made up of tiny teeth-like structures called placoid scales, also known as dermal denticles. These scales point towards the tail and help reduce friction from surrounding water when the shark swims.
• Most sharks have good eyesight. Most sharks can see well in dark lighted areas, have fantastic night vision, and can see colors. The back of sharks’ eyeballs have a reflective layer of tissue called a tapetum. This helps sharks see extremely well with little light.
Sharks are spread across 512 described and 23 undescribed species in eight orders.... that’s a lot of sharks.
The facts Sharks belong to the superorder Selachimorpha in the subclass Elasmobranchii, in the class Chondrichthyes.
• Sharks have been around a very long time. Based on fossil scales found in Australia and the United States, scientists hypothesize sharks first appeared in the ocean around 455 million years ago.