How Baby Sharks Navigate the World

Sharks are formidable hunters that have evolved over 450 million years, making them the most feared creatures in our seas. Great whites have the power to leap 10 feet into the air, while Makos can reach speeds of over 45 miles per hour. However, in their first year of life, sharks are surprisingly vulnerable and are a target for predators, including other sharks. Around 80 percent of some shark species won't make it to adulthood, and adult sharks don't spend any time caring for their newborns. Baby sharks are just another item on their menu, which is why some pregnant sharks travel to shallow water to give birth where big predators cannot go.

Exactly where sharks are born is largely still a mystery, so footage of a shark birth is extremely rare. Once born, many sharks remain in the safety of the shallows in areas known as nurseries. Black tip reef sharks, for example, are born just a few days old and are around 20 inches in length. They are a quarter of the size of an adult and are able to swim from the moment they're born. They dart among the tangled roots in nature's playground, but there is no time to play when you're a hungry baby shark.

Luckily, black tips, like many shark pups, are born with extra fats stored in their liver, giving them enough energy to explore their environment as they learn to hunt for food. Venturing into the shallow bay presents opportunities for a larger meal, but baby sharks face other pressures, such as pollution and habitat loss.

Bull sharks, on the other hand, are deadly and the most versatile of all sharks. They are the only shark species that can move between saltwater and freshwater, making them a threat to humans. However, they choose shallow water estuaries to give birth to their young, far from where any other shark species can go. A newborn bull shark is about as long as a human arm, less than three feet. From birth, they have the ability to live in fresh or saltwater, but a receding tide can leave a baby shark trapped and in grave danger.

Sand tiger sharks, one of the most ferocious-looking sharks, face cannibalism in the womb. Females keep producing eggs to feed the largest embryo left in each womb, but it's not just the embryo's size that gives it an advantage. It's the most aggressive baby sand tigers that are more likely to be born, and that trait is passed down from the males. After a few months, only one dominant baby shark remains in each womb.It is noteworthy that the historical data available for female sharks indicates their year-round presence in this area. Therefore, it is of great interest to observe the behavior of a male shark, whether it will depart or remain with the females. Such observations are crucial for the purposes of conservation and management, as they provide insight into the utilization of this region by these animals.

Prior to releasing the shark back into the water, one final measurement must be taken - the anal temperature probe. This is a homeothermic shark, meaning that it maintains a body temperature warmer than its surroundings, allowing it to thrive in this environment. In contrast, blue sharks and other species that lack this ability must leave. The temperature inside the shark is currently 74.5 degrees, which is significantly higher than the external water temperature. This is a remarkable finding.

With the measurements completed and a new satellite tag attached, the eight-foot-long male shark is ready to be released back into the ocean.

Finally, the poor beagle shark, despite its impressive strength and speed, gets much less attention than its cousins, the great white and the Mako. Pregnant poor beagles are rarely seen, and scientists are still unraveling their many mysteries. They believe that the females stay in cold waters to give birth, and the question is why when other sharks migrate south by winter. Poor beagles are able to use the entire water column in their search for prey, from warmer water near the surface to much colder water at depths of over 4,000 feet.