Sleeping Tigers Of The Seas (sharks)

2023 Author: Molly Page | [email protected]. Last modified: 2023-07-31 03:34

Reason and instincts. What role do they play in animal behavior? For more than a dozen years, this issue has been the subject of controversy among ethological scientists. Moreover, the controversy is usually conducted only regarding our smaller brothers living on land. But the inhabitants of the seas and oceans are generally denied the opportunity to claim the presence of elements of rationality in their behavior. However, the situation is far from simple, as evidenced by the proposed essay.

Six miles from the tip of the Yucatan Peninsula is the small island of Isla Mujeres, a popular tourist destination. Its inhabitants are hereditary fishermen who fish for shrimps, lobsters and sharks, which are eagerly bought for gourmets by restaurant owners. One of the fishermen named Carlos Garcia and found sleeping sharks in an underwater cave. The giant fish lay motionless on the bottom, breathing rapidly and seemed to be in a state of deep intoxication. In any case, they did not react to the appearance of a person. Moreover, these were man-eating sharks that live in the ocean at great depths and are called pelagic in science.

The rumor about Carlos's discovery spread among tourists and eventually reached scientists. But they categorically rejected the very possibility that giant sharks could sleep at the bottom of a shallow cave. To live, they must move continuously. Only then the gills are washed by a sufficiently strong stream of water, supplying them with oxygen in the required amount.

A prominent Mexican biologist Ramon Bravo accidentally heard about the shark phenomenon from one of his colleagues. Unlike others, he did not immediately reject his opportunity, but invited his friend from the United States, Dr. Sylvia Earl, and went on an expedition to the Yucatan coast.

When two scientists and assistants arrived on the island of Isla Mujeres, Carlos Garcia was eagerly awaiting them there, taking the disbelief of scientists as a personal insult and longing to restore the truth. Directly from the ferry, he dragged those who arrived to the mysterious cave. There, for the first time in the history of ichthyology, the members of the expedition themselves observed sleeping sharks. “They were adult Karcharodons,” says Sylvia Earl. - The first impression was that they were dead and we ended up in some kind of underwater "cemetery of elephants" - after all, according to legend, they go to die in some remote place. According to our guide Carlos, even earlier he risked touching them several times and even slightly raised their tails, but none of the predators showed any aggressive intentions towards him.

The behavior of the giant sharks was more than strange. After all, they have practically no enemies, and therefore the need to hide in caves to rest. Traditionally, it was believed that pelagic sharks sleep in fits and starts, not stopping to move so as not to suffocate. And here was a real bedroom. Moreover, its inhabitants, even in a dream, do not stop vigorously passing water through the gills, rhythmically opening and closing their toothy mouths:

Before looking for an answer to this riddle, it was necessary to measure the temperature of the water, its salinity, to determine the content of oxygen and chemical impurities in it, the speed and direction of the current in the cave, in short, to do many far from safe, although the sharks seemed to behave quietly, preliminary research.

Unfortunately, the deteriorating weather prevented the implementation of the planned program: it began to storm. In addition, one after another, the instruments broke down, and the sharks did not show much desire to help solve their secret. No, they did not attack people, but they did not allow themselves to be touched, let alone to measure the temperature of their bodies. The most surprising thing was different. Although the predators could have gotten rid of the intrusiveness of intruders with the help of their terrible toothy mouths, they showed an amazing tolerance that could hardly be expected from them.

… The third expedition turned out to be the most successful. Garcia was so carried away by the mystery of "shark bedrooms" that he spent all his free time scuba diving on the coastal reefs and banks. He discovered two more caves with sleeping "tigers of the sea": one on the Puente reef, the second on the Cadena reef. The latter was only 33 feet deep, making it much easier to dive into the "laboratory". And most importantly, the sharks in it behaved much calmer in their sleep than in other places. One of them, for example, allowed herself to be observed for four hours before returning to normal, forcing the researchers to hastily leave her dormitory.

Analyzes of the water taken from all three caves showed that it had lower salinity everywhere, was more oxygenated, and also contained a higher percentage of acids. This indicated that fresh water was supplied to the shark "bedroom" near the Isla Mujeres through underground wells, similar to artesian wells.

Related article Interesting facts about sharks

And yet it remained a mystery why sharks chose these places for their sleep? One of Dr. Sylvia Earl's assistants suggested that this mixture may have an "intoxicating" effect, similar to what happens to a person when he takes a large dose of alcohol. Well, their preference for several caves is explained by the fact that they serve "the strongest cocktail." This version, however, had one significant flaw: it did not give an answer to the question of why sharks swimming in rivers for tens of kilometers do not "get drunk" and do not sleep.

By the way, the very term "sleep" turned out to be not entirely accurate: the sharks did not sleep at all in the full sense of the word. Their eyes constantly followed the actions of the people around them. Another thing is that the predators did not try to attack, although in a normal state they would not fail to do so, but simply swam away if they too much prevented them from enjoying their well-deserved rest after many days of raids in the ocean.