In the vast ocean, all creatures are vulnerable. Bottlenose dolphins are cetaceans that rarely become prey, thanks to their size, their intelligence, the use of echolocation and their level of socialization that gives them a significant advantage by staying in groups and intimidating their opponent. However, two predators will take the smallest opportunities to feed on dolphins: killer whales and sharks.

We know that the killer whales are expert hunters, especially when they hunt in organized groups. Although there are few documented cases, these animals that are the world’s largest dolphins, attack other species of smaller dolphins, mainly young, newborn or sick. To do it they separate the mother from the calf, making impossible to the latter defend its offspring.

However, a group of orcas does not feel intimidated by a large pod of dolphins. Although there are no records of this kind of attack to bottlenose dolphins, there are videos where a pod of killer whales approaches aggressively to groups of dolphins of other species, and as if they were seals, they beat them and throw them into the air until they are stunned and finally feed on them. Several types of dolphins suffer this kind of aggression, and the bottlenose dolphins are likely part of this list.

Regarding sharks, the most dangerous species for members of the genus Tursiops are the largest: tiger shark, sand shark, bull shark and, of course, the great white shark. It is not uncommon to observe dolphins with scars from shark attacks, which means they are not easy prey and their escape techniques often help them survive.

A study conducted in Shark Bay, Western Australia, revealed that 95 of 128 bottlenose dolphins analyzed showed scars from shark bites, mostly from tiger sharks. The frequency of new body marks and the high attack rates suggest that bottlenose dolphins are at risk in this locality more than in other parts of the world.

A few cases with rays are known. Although they are not dolphin predators because they have a diet based on small fish, mollusks, and plankton, the trauma and infections they cause with the sharp edges of their tail sometimes become deadly.

Indeed dolphins and all cetaceans like whales and porpoises evolved from animals that lived, reproduced and died on land. In fact, their closest relative alive is the hippopotamus, which in turn also relates them to the artiodactyls.

The common ancestor of dolphins and hippos is an animal called Pakicetus that roamed the Earth about 50 million years ago. Pakicetus had a four-leg functional anatomy, elongated snout, flexible neck and a very long tail, morphology that laid the foundation for the subsequent appearance of cetaceans.

Millions of years later, creatures like Ambulocetus and Kutchicetus emerged with body characteristics increasingly adapted to the marine world.

While the former is the commonly accepted theory, others suggest that cetaceans descend from the Mesonikia, prehistoric animals that lived on Earth about 55 million years ago. Its appearance was similar to that of a tiger, and the evolutionary change began while searching for food in the disappeared sea of ​​Thetis.

The explanations about the evolution of dolphins are:

One. The scarcity of food on land forced some coastal populations to venture into the ocean for food, which gradually adapted their anatomy to their new habitat.

Two. The other theory has to do with the climatic changes of the era, which forced them to enter the water to get a convenient place with satisfactory temperature and abundant food.

Visible evidence.

Several indicators confirm that dolphins evolved from terrestrial animals, and these are the most evident:

1. They have a robust bone structure rather than a cartilaginous skeleton like sharks or fish.

2. They are mammals because they feed their young with breast milk from the mother.

3. Dolphins breathe air like us. They can not breathe underwater like fish because they have lungs instead of gills.

4. Dolphins have vestigial bones that once were legs and pelvic bones where they were attached.

5. These cetaceans are warm-blooded.

Even that some scientists still debate about the dolphin ancestors and their relation with other species, there are enough probes to confirm that these cetaceans undoubtedly descend from terrestrial animals.