This "master of underwater expression management" is actually a "close relative" of ferocious sharks

If you look up at the aquarium and see a "smiley face", it may be a swallow ray. The eyes on the smiley face are actually its gills, and the teeth are like the teeth of a smiley face. Because of its swallow-like body shape, it is like a swallow in the air when it cruises in the sea, and its movements are light and agile, so it is called the "swallow ray".

The swallow ray is a cartilaginous fish with a flat, square body, a blowhole behind the eyes, no swim bladder, a long tail, a brown back, and a light gray belly. The swallow ray is more than one meter long, but the long tail accounts for 70%. The rest of the flat body is dotted with bright dots, making the body look very delicate. Although the swallow ray looks light and elegant, it actually has the IQ of a six-month-old child. They are shy by nature and do not actively attack people, but they are not easy to mess with when threatened. The whip-like slender tail is not a decoration, but has a serrated stinger on it, which is their best weapon. Once a person is stabbed, the wound will be unbearable, and if rescue is not timely, it may even be life-threatening.

About 180 million years ago, the ancestors of rays and sharks were the same species. In order to adapt to the life on the seabed, they hid their bodies in the sand on the seabed for a long time. The rays family eventually evolved into its current appearance, and was also nicknamed "flattened sharks". Therefore, rays and sharks are close relatives of the same clan. Because they are from the same clan, some of their habits are also similar, for example:

1. Neither rays nor sharks have gill covers. They generally have five pairs of plate-like gill openings on the abdomen, a mouth at the top of the abdomen, and pavement-like teeth.

2. Like sharks, they have the ability to "replace teeth throughout their lives". The teeth of stingrays are paved with stones and have a smooth surface, which can crush crabs, shrimps and other crustaceans like a mortar. Because of their unique way of eating, their teeth are often worn out. When the front row of teeth "become blunt" and are no longer convenient to use, they will automatically fall off, and the back row of teeth will fill the vacancy, and the cycle will continue.

The naturally smiling manta ray family is not only a good swimmer in the sea, but also provides a high reference value for the design of bionic underwater vehicles. In recent decades, researchers from various countries have developed a large number of bionic underwater vehicles, which have the advantages of wide operating range, good maneuverability and concealment, and low noise. They have great application prospects in marine scientific research, marine resource development and military fields. As a typical MPF propulsion mode fish, it has received more attention and research from scholars at home and abroad. (The MPF propulsion mode mainly relies on a variety of flexible fins such as dorsal fins, pectoral fins and pelvic fins of fish to generate propulsion)