Sharks – killers from the depths
From ancient times sailors have created legends about a large marine predator. Its fin sticking above the surface of the water was a sign of upcoming death. Sharks – a general name for a group of elasmobranch predatory fish with a cartilaginous skeleton. Sharks are distinctive for their streamline, sedge-shaped torso, a heterocercal (asymmetric) caudal fin, 5 – 7 respiratory holes (gills) located right behind the head and extremely sharp teeth.
The first sharks appeared on Earth more than 420 million years ago. Today we distinguish over 500 shark species.
Sharks – the largest fish
Sharks are the largest fish to swim the seas and oceans in the world. Most of them are slender, dexterous swimming predators spreading fear among even sizable aquatic creatures. Their teeth are an utterly dangerous weapon during fights with animals even larger than the shark itself. The title of the largest shark in the world belongs to the whale shark.
Great white shark – man-eater shark
White pointer (great white shark) is the largest threat to humans. It has several rows of powerful, massive teeth, which look amazingly when the shark launches its attack…
Sharks are provoked by blood…
Great white sharks often swim in close proximity to beach areas, where cases of their attacks on humans sometimes occur. As a result, these sharks have reputation for being dangerous animals. Human attacks take place usually when the person swimming e.g. on a surfboard is confused with a seal.
A shark never attacks humans first, unless it senses blood in its surroundings. Precisely blood and water splashing are the most effective incentive to attack. A shark can sense a small amount of blood from up to 500 meters! Then it enters the so-called hunting frenzy and attacks – literally – everything in its sight… They are the reason for several hundred human deaths yearly. Presumably, the victim list is much longer, yet some countries of the Third World do not maintain any kind of records.
Australia and Egypt – dangerous destinations
The highest shark-related mortality rate appears on the Australian coast. Mostly surfers swimmers and divers become shark victims, as well as occasional beach bystanders – Egypt shark attacks in 2011.
No sharks in the Baltic Sea…
The Baltic Sea is a cold region, while sharks prefer a warmer climate. This, however, does not dictate the sharks’ absence in cold waters. In the western parts of the Baltic Sea the porbeagle (Lamna nasus), spiny dogfish (Squalus acanthias) and sometimes allegedly angelshark (Squatina squatina) appear. A porbeagle was caught by Polish fishermen from Kołobrzeg.
Sharks have the largest brains among fish
Sharks are fish with the largest brains and have more senses than we do: sight, smell, hearing, taste, touch, lateral line (sensing water motion) and electroreception (detects electromagnetic field changes). Sharks see 10 times better than humans do in the dark.
Detailed characteristic / size
- Length: 0.17 m – 20 m
- Weight: up to 12 tons
Specific shark characteristics
More about sharks, the descriptions of distinct species, including the largest and most dangerous sharks may be found in the section about these giant and perilous fish – Sharks.