As a general rule of thumb, sharks have been observed actively foraging for prey at dawn and dusk, as well as into the night. However, with over 500 species of shark recorded throughout the world’s oceans, it can be hard to quantify individual feeding patterns.
With recent advancements in technology and a collaborative effort from scientists across the globe, we are beginning to understand more about these marine, cartilaginous fish.
With such a huge diversity of sharks, it comes as no surprise that diets and feeding times vary.
Some, such as the tiny dwarf lanternshark, feed on shrimp and small fish, that are predominately active at night.
Others, such as the gargantuan whale shark, the largest fish in the world, feed solely on microscopic plankton. Much of their diet is photosynthesizing phytoplankton, which use the sun’s energy to create food. Therefore, whale sharks feed mostly during daylight hours.
However, some species, such as the tiger shark, are opportunistic hunters. Quite like a hungover student, an opportunistic feeder will eat whatever it can find, wherever it may find it, and at whatever time.
So, why do sharks feed at night?
There is a scientific explanation as to why these oceanic predators hunt during the twilight hours.
Beyond 200 meters of depth, it is exceedingly rare for any light to pass through the water column. At a time of little light hours, for example, dawn and dusk, limited light reaches this zone, allowing predatory sharks to hunt without being seen.
It is also thought that fewer species are predominantly active solely at night. This is because reduced lighting makes nighttime a dangerous time to be exposed. After all, it’s a dog-eat-dog world out there. Or is it a shark-eat-shark world…?
Not only this, but in tropical regions where many shark species can be found, the heat of the surrounding ocean can be too much. Sharks are extremely sensitive animals, and any anomalies will have huge implications on their behavior. Because of this, many species hunt when the temperature is slightly cooler than the midday heat.
How often do sharks feed?
Of course, with a great diversity of shark species, a great variation in size is observed.
Typically, most shark species, independent of their body size, will consume anywhere between 0.5 and 3% of their body weight per feeding. This is a generalized rule, with many species feeding correspondingly to their diet.
For example, despite being the largest fish in the ocean, the whale shark is a filter feeder. They swim in the sunlit zone of the ocean, filtering large quantities of drifting plankton. Plankton are incredibly small, and to optimize energy efficiency, a whale shark must consume over 21kg of plankton per day – this is thought to be the equivalent of the size of a wild pig!
In contrast, oceanic shark predators such as great whites or bull sharks, actively hunt and capture prey. Similar to tiger sharks, mentioned above, these shark species are opportunistic, and feed on anything they come across in the vast ocean dessert.
Due to the nature of their feeding mechanisms, many sharks cannot chew their prey very well. Instead, they tear huge chunks of flesh and swallow it whole.
Do sharks feed every day?
This depends on the species of sharks. Large, filter feeding species most likely feed every day to maintain an active metabolism.
As a result of a shark’s poor table manners of no chewing, many large carnivorous species require at least a few days between meals to fully digest their dinner. As with everything in nature, there are exceptions.
Some species can go up to 6 weeks without a single meal.
Incredibly, the longest recorded time observed for a shark not consuming a single meal was a 15-month period. This staggeringly long time was of a swell shark, a Pacific Ocean-going fish found from Central California to Southern Mexico.
Like many other marine animals, pregnant females will fast. This means during the gestation period, an average period of 9-12 months, the females will not eat anything. It is unknown why females refuse to eat during this period, but scientists hypothesize that it could be to avoid predation themselves.
Despite the mother not eating, inside the womb of certain shark species, an entirely different story unfolds. A battle rages between the developing shark embryos, with the largest of the embryos cannibalizing all but one of its other littermates. This is a common practice in carnivorous, tropical sharks such as sand sharks and bull sharks.
Interestingly, multiple males mate with a single female. Within the womb, offspring from multiple fathers compete to be born. This is an evolutionary strategy deployed by females to ensure only the fittest offspring will be born.
To conclude, whilst some sharks feed exclusively at night, such as the aptly named night shark, many species hunt actively around dusk and dawn.
Some species, such as filter feeds like the whale and basking sharks, feed daily.
However, the majority of shark species feed just a couple of times a week.