Belly buttons and a vegetarian diet: some interesting facts about sharks

When sharks are mentioned, the first thing that comes to mind is that they are large, not very intelligent, have sharp teeth and should be avoided. However, according to IFLScience, researchers who have been studying these marine creatures for months know how deceiving this image is.

First, scientists say the diversity of sharks is surprising. Second, the differences between species are so great that it can sometimes appear that some are almost unrelated.

In Focus. Technologies emerged telegram channel. Subscribe to avoid missing the latest and most exciting news from the world of science!

The new study by white shark researcher Georgia French, PhD, of the University of Sussex, and colleagues from the United Kingdom and South Africa, shows that there can be significant differences not only between species but also within the same species (between males and females). What’s more, scientists observing great white sharks in South Africa found that some females did not make the transition from eating fish as children to eating seals and other mammals as adults. The results of the study showed that some adult females actually specialize in catching fish and use different habitats than males.

The team reached this conclusion after performing stable isotope analysis, a type of chemical examination, of small pieces of muscle collected from free-swimming great white sharks. As a result, scientists were able to learn how predators eat over a period of about two years.

Note that differences in how the sexes use resources are called sexual segregation and are quite common in sharks. The causes of sexual discrimination can be extremely complex, but sometimes they are also associated with different temperature and nutritional requirements, as well as the need to give birth in specialized nurseries.

The study authors also believe that the courtship and mating process may also be one of the reasons why females reach large sizes; It is known that males without hands are forced to hold females with their teeth. Interestingly, scientists have also previously noted that female small spotted cat sharks hide in shallow water caves during the day to avoid aggression and harassment from males.

According to French, the situation becomes even more intriguing when we look more broadly at the diversity of sharks among different species. Science knows more than 400 species of sharks, and they range in size from 20-centimeter pygmy angler sharks to 18-meter whale sharks.

Sharks also come in an extremely wide range of shapes, from flat, ray-like angel sharks to round, frilled, eel-like sharks. The researchers also found that an animal’s tooth shape can vary from crushing plates to rounded, blade-like teeth, depending on the species.

Sharks are also divided into many reproductive types: Some lay eggs, others incubate the eggs within themselves, resulting in babies developing in the female’s womb before they are even born. Others give birth using the placenta and umbilical cord, similar to mammals. The umbilical cord is tied between the pectoral fins, and when babies are born, they are left with an umbilical wound, that is, a belly button, which is visible for several weeks until it fully heals. Moreover, some observations show that female sharks can sometimes reproduce without a partner.

The authors of the study hope that the results of their study will help protect shark species at risk of extinction in the future.

Previously Focus wrote that scientists had photographed a newborn great white shark for the first time: they had never been seen as small.