Speartail fish is the only species in the family Speartail of the order Coelacanthidae of the order Coyropodidae. Total finfish first appeared 300-400 million years ago, and it was thought to have become extinct 70 million years ago until 1938, when a live speartail fish was accidentally caught near the coast of southern Africa. This discovery attracted the attention of all walks of life around the world, and it was successfully captured in the same sea area many times. Speartail fish is the only species of total fin fish that has survived to this day, and its genes have not changed for nearly 300 million years, which can be called a living fossil.
Speartails can reach up to 2 m in length and weigh up to 90 kg. The body is long and fusiform, with a thick body, a large head, a wide mouth, and sharp teeth. The skull has a special intercranial joint with 1 pair of large laryngeal plates between the lower jaws. The body is covered with large , thin oval, circular scales , and the exposed parts of the scales have many small crests or warts , resulting in a rough surface and smaller scales at the back of the body and at the base of the fins. The spinal cord is present for life and has small pieces of hard bone above and below it. The swim bladder is small, has no respiratory function, and only plays a role in regulating the specific gravity of the fish body in the water.
The even fins (pectoral fins, ventral fins) are long, with well-developed muscles at the base, scales on the outside, and the arrangement of the inner bones is similar to that of terrestrial vertebrate limb bones, and this fleshy fin can not only support the body, but also move along the land to a certain extent. This shows that the fins of speartail fish are already in the process of transforming into limbs that can move. There are two dorsal fins: the first dorsal fin is strong and bone-boned, crested, and spine-like; the second dorsal fin is similar in appearance to the pectoral fin, ventral fin, and fin, and is stalk-shaped, with the fins growing on a thick fleshy fin stalk. The middle leaf of the caudal fin protrudes in the shape of a spear, so it is called speartail fish.
It is currently mainly found on the southeast coast of southern Africa, and has been found occasionally in the waters of Indonesia in recent years. Diurnal and nocturnal, generally living in water at depths of 200-400 meters. There is a freshwater area in the seawater where speartails are found, and it is in this freshwater area that they live in, and they only float to the surface of the sea in a short two months from November to January of the following year. It is carnivorous and preys in a sprint manner, specializing in squid and fish. According to its inner ear stone ring, the lifespan of speartail fish can reach 80-100 years.
Although there are many types of fish, the discovery of speartail fish is undoubtedly the most powerful of all fish so far, not only because they are a rare or ancient fish, but also because they are a "missing link" in biological evolution, and their discovery has closely linked all the vertebrates on land today and the fish in the water. Speartail fish's characteristics of producing muscles, bones, and limbs from their fins provide living evidence for the theory that terrestrial organisms evolved from water.