Lords of the sea ... Kings of the ocean, these amazing creatures almost reach physical perfection, which has allowed them to evolve for thousands of years. Their size, biology and appearance varies greatly. Some lay eggs, others give life replics of their parents.
The two largest fish are sharks in the world! the basking shark and the whale shark. Their structures or skeleton is formed by a resilient and flexible material called cartilage, a lighter material than bone which gives them greater speed and flexibility, plus usually torpedo shape that allows them to "fly" in the water such as a plane does in air.
Speaking of the senses of the sharks we mention that the view is limited because their eyes are too far apart to see what they have in front, but they have a special weapon: Lorenzini´s blisters (sensitive pores located in the nose), which are electroreceptor organs, and are in large quantities from hundreds to thousands, sharks use these Lorenzini Ampullae to detect electromagnetic fields – all living organisms produce these fields, and so their prey.
Ears are specialized in the frequencies that are transmitted under the water, perceive a boat on a reef from 2 km. With his sense of smell can detect one drop of blood between 1 million drops of water. They have no hands to touch, they touch by direct contact or by the perception of vibrations, throughout the body they have a Lateral Line (sensitive nerve cells vibration thereby detect objects several feet away), from the tail fin and with extension in the head and around the eyes, that detects vibration or movement which makes they can locate with great precision the prey.
Sharks teeth are constantly replaced throughout their lives and how they differ in each species. The shape of the teeth depends on their diet, every shark will have a different form by which you can identify it.
They also have various forms of tails to identify them. The caudal fin considerably varies among species and adapt to the lifestyle of each shark.
Sharks have fatty liver (bony fish have swim bladder), which helps to float, but even with this large liver (can reach up to 25 % of their body weight), the shark is heavier than water and tends to sink, which is why most sharks must swim constantly for his life ... born to swim.
The shark skin unlike bony fish that has scales, has a perfect protective shield formed by denticles, these denticles are tooth-like structures (if you touch them from head to tail skin is smooth, if it goes on contrary is like sandpaper) and also gives greater hydrodynamic control.
Although most sharks are solitary, rarely travel alone. Their companions are the remoras and pilot fish. The remoras stick with its suckers and have a symbiotic relationship – both benefit – they feed on parasites and they get their cleaning service. The pilot fish, instead travels to the front of the shark taking advantage of pressure waves and feed on the leftovers, plus it gets protection as well.
Sharks you will be able to find in this area:
Bull Shark: a shark with a farily robust, fusiform body and a short, obtuse snout. It leaves in inshore waters, between the surface and 150 metres and swim up rivers (fresh water). It feeds not only fish, but also on marine mammals and invertebrates. Its ovoviviparous and meassures up to 3.4 metres. Its consider a dangerous shark. Bull Shark dives in Playa del Carmen, only in season from December to March.
Whale Shark: a shark with a massive cylindrical body with prominent carinas running along the flanks to the caudal peduncle. The snout is wide and flattened, with a wide terminal mouth. It feeds mainly on plankton and small pelagic fish. It is ovoviviparous and measures up to 14 metres long, found in tropical and warm temperate seas and appears to undertake long-distance migrations. You can swim and snorkel with whale sharks !
The Lazy Shark – the Nurse Shark with a robust, ventrally flattened cylindrical body and a wide rounded snout, it lives on the sea bed, in inshore waters from 3 to 35 metres deep. It feeds on crustaceans, molluscs and fish. It is ovoviviparous, and meassures up to 4 metres long. This shark does not need to swim to breath, it has a perfect adaptation to lay on the sea bottom.