The anatomy of the shark is fascinating as researchers continue to delve into the unique features that enable it to live and hunt as it does.
These include physical traits and processes that assist the animal in all spheres of its life without the conscious control of the fish.
The anatomy of the shark is explained below.
1. Shark Skeleton
The skeleton of a shark is the biggest part of it’s anatomy and is not made of bone but of lighter, more flexible cartilage. Some areas of the skeleton are harder than others for added strength. Other areas, like the snout, are softer in order to allow the shark to absorb blows.
Swimming muscles are attached directly to inside of the shark’s body to allow for energy saving and ease of movement. This means that, with no rib cage, a shark will literally be crushed under the weight of its own body if it is not kept in the water.
Caribbean Reef Shark cruising over soft corals, with a little remora along for the ride.
2. Digestive Tract Of Sharks
The shark’s oesophagus is short and wide to allow smaller prey to be swallowed whole or large chunks of prey to be gulped down as sharks do not chew their food.
This leads to a u-shaped stomach and, often, to as spiral valve (which is convoluted to increase the surface area for improved absorption). From here, food is excreted via the rectum and cloacae.
3. Sharks Circulatory System
The heart is also part of the anatomy of a shark ad is s-shaped. Blood flows from it to the gills to be oxygenated and then through the body to feed muscles and organs. These animals have a relatively low blood pressure, and need to keep blood flowing so that it can be oxygenated.
Blood is kept circulating and pumping over the gill slits by the shark’s muscle movements as well as by the opening and closing of its mouth.
4. Gill Slits Of Sharks
As with other fish species, sharks breathe by means of gills, and not lungs. Water is pumped over the gill slits. Blood in the gill filaments absorbs oxygen from the water being pumped over them, which is then carried to the muscles and organs in the rest of its body.
Shark’s gills are not covered which is unique for the anatomy of the shark. There is a spiracle, which is a modified slit, just behind the eye.
5. Shark Stomach
A shark eats only about 5% of its body weight per week. In addition, it can go for weeks with no food at all due to its cold-bloodedness and the resulting slow metabolism.
6. Shark Buoyancy
Sharks are kept buoyant by their large livers and their cartilage, which is much lighter than bone. The liver is oily and contains squalene, which assists in keeping the shark from sinking to the ocean floor.
The liver is so large that it actually accounts for about 30% of the shark’s total body mass. Their fins and constant movement also assist in keeping them from rolling and sinking.
7. Thermoregulation Of Sharks
The body temperature of the shark is at about the same temperature as its surrounding habitat, making most species “cold-blooded”.
Some sharks, although being broadly defined as being cold-blooded, have a body temperature that is slightly higher than the water. Examples are Mako and Great Whites sharks.
As one explores the shark’s anatomy, physiology and adaptations in more detail, it becomes clear that this animal has been designed and built to survive the cold depths of its hunting grounds.
Interesting Facts About The Anatomy Of The Shark
The anatomy the shark is a key factor for their success as predators, influencing their hunting and living habits. Generally, sharks are cylindrical in shape with tapered edges.
This streamlined structure allows these carnivorous hunters to cut through the water in pursuit of their prey. 7 Intersting facts about the anatomy of the shark can be found below.
Most sharks average a length of about 5.8 to 7 metres, much the same as human beings. The smallest species, known as the Lantern Shark, measure less than 20 centimetres, while the enormous Whale Shark (believed to have been the ‘whale’ described in the Biblical account of Jonah) measures an astounding 12 metres, on average.
The colouring of a shark’s body is technically a part of the anatomy of the shark and has been designed with camouflage in mind. The top of the shark, the dorsal side, is darker than the ventral side, or underneath, of the body.
This ensures that, when seen from above, the darker side of the body blends in with the blackness of the ocean’s depths.
When viewed from beneath, its lighter ventral side is much the same shade as the surface of the ocean, which is brightened by sunlight. Some sharks have stripes or spots, particularly in their early years. Others become lighter over time, while still others remain one colour for their entire life span.
The skeleton of the shark is different from other fish species in that it includes no bone. This part of the anatomy of the shark is all cartilaginous. In some areas of the body, the cartilage has calcified to make it somewhat harder and firmer, but it still does not qualify as bone.
4. The Jaw
5. Shark Teeth
There are rows of teeth (serrated for some species and flattened for others) that are replaced on a regular basis to ensure that the animal is always equipped with sharp, effective weapons and tools.
The shark’s skin is an interesting part of the anatomy of the shark and made up of dermal denticles. These collagenous fibres act as a corset and an exoskeleton. Shark skin is used as sandpaper and, when treated, as leather.
The muscles are attached directly to these collagenous fibres, which is effective in saving energy. There are tiny ‘teeth’ on the skin that are in place to reduce turbulence, allowing the shark to cruise unhindered through the water.
A shark cannot swim backwards due to the structure of their fins. Their tails are used for forward thrust and propulsion while the caudal fin assists.
The pectoral fins keep the animal lifted, working against the downward pushing of the caudal fin, and assisting in steering. Depending on its specific needs, different sharks have different tails.
Sharks breathe by means of gills, not lungs. They usually have between 5 and 7 sets of lateral gill slits.