It is enjoying a "sunbath" in the sea. It looks cute but seems to be indifferent to life and death?

Along the coast of our country, especially in the vast waters of the South China Sea islands, there lives a kind of sunfish with a strange shape and huge body.

The reason why it is called sunfish is that they often lie on the sea surface to enjoy "sunbathing".

If you look closely, you will be attracted by its silly and cute appearance.

The cute looking sunfish is a " weird " marine creature.

It will definitely give you a better understanding of marine life.

" Large rollover scene "

No tail?

The round-headed and round-brained sunfish is one of the most peculiarly shaped fish in the world. It has a wide, flat and huge body, but very small eyes and mouth. It is a large fish with a gentle personality.

What’s even more peculiar is that it has no pelvic fins or tail fins, and its entire hind half of the body looks like it was cut off by a knife, so its entire body is oval in shape.

The sunfish's dorsal fin is located far back, opposite to its tall anal fin, and looks like a pair of wings on an airplane. Therefore, the sunfish looks more like a marine "flying saucer" swimming in the deep blue sea[1].

In fact, the sunfish does not have no tail, it just has a short tail.

According to research, this fish is no different from other fish species during its embryonic stage, but only develops its strange appearance when it grows up.[2]

As the sunfish fry grow up, their tails gradually degenerate and shrink. When they are 13 to 80 mm in length, the tail fin disappears completely, leaving only a rudder fin similar to the tail fin. It has a lace-like shape, so it looks like it has no tail.[3]

Many aliases

The scientific name of sunfish is " Molamola ", and it has different names in different places, mostly because of its strange appearance and interesting habits.

In Latin, Mola means " millstone ". Because the sunfish looks like a millstone when lying flat on the sea surface, the Swedish naturalist Linnaeus named it "Molamola" in 1758[3].

During the day, sunfish often lie flat on the sea to bask in the sun in order to attract seabirds to peck at the parasites on their body surface and to raise their body temperature to enhance gastrointestinal motility. Therefore, Europe, the United States and other countries call them " sunfish ."

At night, the sunfish stirs up the sea water when it swims, causing the Noctiluca scintillans in the sea to glow. At the same time, the microorganisms attached to its body surface also emit faint light, so it is also called the " moon fish " [3].

In Japan, people call it " Mambo fish " because its swimming posture on the sea surface is like dancing the Mambo dance. The Chinese call it "Sunfish" or "Sunfish" because they think that such a funny body is difficult to keep balance in the ocean, and they always flip on their side on the sea surface. However, some places think that "flipping" is not auspicious, so they call it " Wheel Fish " [3].

In addition, because the sunfish has a laterally flattened body, small eyes and mouth, short pectoral fins, and no pelvic fins, it looks like a fish head, so the Germans call it a head fish .

The many aliases of sunfish also reflect its wide distribution. Except for the Arctic Circle, they can be found in almost all waters of the world.

Don’t care about life and death?

Interestingly, fish swim mainly with the help of their tail and pectoral fins. Large fish usually swim fast. However, sunfish have no tail, are huge in size, and have very short pectoral fins that cannot propel them and can only be used to maintain balance. Therefore, they have no swimming ability and can only rely on the swinging of their two extra-long dorsal and anal fins to control their direction, moving slowly forward or drifting with the waves[2].

Sunfish usually move only when pushed by seawater, so people often call it a lazy and stupid fish. When it encounters natural enemies such as killer whales and large sharks, it does not run away or resist, but silently endures the bites of natural enemies. Its life and death depends on whether the natural enemies are full.

In addition, the skin of the sunfish is very thick and has no nerve endings. What is eaten is the thick fish skin, and the fish does not feel any pain at all.

Professional over-birth households

Sunfish are often eaten by other fish in the sea, but the reason they have not become extinct is their strong reproductive capacity. Sunfish are considered the most fertile vertebrate in the world. It is said that a female fish with a body length of only 1.4 meters has been observed to have 300 million eggs in its ovaries, which is several orders of magnitude higher than that of normal fish[4]. Given such a large number of eggs, it goes without saying that the size of a single egg is very small.

This method of reproduction with extensive planting and low yields inevitably leads to a low survival rate. However, even if the success rate of fertilized eggs developing into adult fish is less than one in a million, such a huge number of eggs is enough to ensure the continuation of the race of these "sea monsters".

Growth Champion

The growth rate of sunfish is amazing. When they are born, they are only two millimeters in size, smaller than a child's fingernail. If you don't look carefully, you can't observe their existence at all. But adult sunfish can reach more than 3 meters in length.

The weight of a newly hatched sunfish fry is only 1 gram. If we extrapolate this based on the sunfish's maximum weight of 2,235 kilograms, then its weight growth rate is on the order of 10^8, making it the growth champion of marine fish in the world[3].

Sea "Angels" & Passionate Youth

Sunfish are also known as marine doctors. Studies have shown that sunfish secrete a substance that can help heal injuries of other fish, making them true “angels” of the sea.[5]

Sunfish are the only known warm-blooded fish in the ocean. They generate heat by constantly flapping their pectoral fins. Their muscle temperature is 4-5 degrees Celsius higher than the surrounding seawater on average. This unique body structure makes them excellent divers, allowing them to remain stable even in icy waters at a depth of about 800 meters[6].

[1] Ye Zi. “Flying Saucers” in the Ocean[J]. Exploration of Nature, 2003, (4): 31.

[2] Wang Yunxiang. Weird “car rollover” [J]. Ocean World, 2001, (12): 14.

[3] Shen Jinao, Jin Xinbo. The strange sunfish[J]. Nature, 2011, (3): 76-77.

[4] Ouyang Jun. The Magical Sunfish [J]. Smart Spring (Children's Edition), 2013, (4): 17.

[5] Zhou Tongxuan. The most bizarre sunfish[J]. Extracurricular Life, 2019, (C3): 86-89.

[6] Blue New Things[J]. Ocean World, 2015, (7): 2-3.