Fish
The one-horned rhinofish lives in tropical seas from the Red Sea to the coast of Japan. It prefers calm waters, reefs and lagoons. Rhinoceros is peaceful in nature, feeds on bottom algae and can reach 70 centimeters in length. Not all representatives have a horn on the forehead and it does not grow over time, it is absent in young animals. Their horns are hard and made of bone, but biologists don’t know why they are needed. One hypothesis is that it reduces resistance while swimming, but there is no evidence for this. Rhinofish are edible and delicious, and ancient Hawaiians valued them for their tough skin that could be stretched over drums.
But the swordfish has a functional “horn.” Unlike the rhinoceros, it is an active predator that can grow up to 4.5 meters. Its “horn” grows from its upper jaw, not its forehead. It is often assumed that this long protrusion acts as a spear that pierces victims thanks to the fish’s enormous speed (36 to hypothetically 100 km/h), but this is not the case. In reality, the “sword” works like a sword and cuts fish victims. The researchers also suggest that the tip could be used for defense against other large predators.
insects
The rhinoceros beetle is one of the largest insects in Europe, with a body length of up to 4.5 cm. The species lives on wood, and the larvae develop in rotten logs. Near human settlements, rhinoceros beetles have even adapted to thrive in rotted manure or garbage heaps, as long as there is plenty of plant debris. It is noteworthy that the insect lives 2-4 years in the larval stage, and the adult (insect) lives only a few months. As an adult, the insect does not feed and lives off the reserves accumulated during the larval stage.
Only males have a large horn, while in females it is almost not noticeable. In healthy males, the horn is long, curved and pointed, so that the insect really begins to resemble a rhinoceros in profile. With the help of this growth, the insect drives male rivals away from females, ideally by throwing them off the branch. The size of the horn depends on the insulin and related molecules. Because insulin levels are affected by nutrition and stress, large horns cannot develop in starving or poor-health insects. Females use their horns to find suitable candidates for mating.
snakes
The rhinoceros viper’s horn actually grows on its nose. Relatively long and thick, this snake can grow up to 1.2 meters and lives only in Equatorial Africa. It is mostly active at night, hiding during the day in fallen leaves, in burrows, under dead trees or in the tangled roots of forest trees. It can climb trees thanks to its prehensile tail.
The horn (or several horns) of these snakes consist of scales and are not very hard. The purpose of this protrusion is not entirely clear to biologists, but it probably helps escape the body’s characteristic snake-like outline. This allows the snake to camouflage itself against the background of the forest floor and hunt by ambush.
There are other species of snakes around the world that have similar but less prominent protrusions on the snout. Because they are often from different species and their bearers live in very different climates, horns probably evolved independently and for different reasons. For example, the horns of desert snakes may protect their eyes when buried in sand, but many biologists find this concept dubious.
whales
Although at one point the narwhal could be considered a narwhal. It is included in the suborder of cetaceans, along with dolphins. Narwhals live in the northern seas and can be up to 4.5 m long and weigh up to 3 tonnes. These animals feed on cephalopods and bottom fish. The horn also helps them in this – with its help, narwhals push prey away from silt and sand.
From a biological perspective, the narwhal’s horn is its tusk, a modified tooth, always the one on the left. The right one is hidden inside the head, but in abnormal cases two teeth can be found. A horn develops in males and sometimes in females, but as a rule the female’s tusk is noticeably shorter.
The function of the horn puzzles zoologists. At first glance it looks useless and fragile, but it actually bends well. It was believed that the function of this organ was the same as that of the peacock’s tail – to attract females to mating rituals and to clarify hierarchical status in a non-violent way. But drone video from August 2016 did not show the tooth allowing the Arctic cod to be stunned while feeding.
Additionally, the horn is rich in nerve endings and can be used to obtain information about the environment. Sometimes narwhals break the ice underwater to breathe.
birds
Hornbills are a large family that includes dozens of genera found in Africa and southern Asia. Some have huge protrusions on their beaks, their helmets look like horns. For example, the Malayan kalao has such a helmet – sometimes it is almost parallel to the beak, sometimes it is pulled up.
The red-billed hornbill has a smaller, more crown-like growth.
The purpose of such “horns” is a mystery to biologists. Due to their hollow structure, they are light and cannot be used as weapons. They probably act as resonators to amplify screams. However, the “horn” of the helmet-beaked kalao is bone, not hollow, and is used to hit the opponent in aerial battles for territory. Some hornbills, such as the southern yellow-billed lek, which are classified in this family due to taxonomic relatedness, have no horns at all.
In almost all cases, scientists are unclear about the function of the horn. For narwhals, for example, it does not help survival at all. It is interesting that even in real rhinos the combat function of the horn is not the only one. He can really penetrate his opponent, but he is also there to show off his threat. Finally, it can be used to dig in the ground, nudge babies in the right direction, or even collect feces into a pile to create a territorial mark.
And don’t forget about the common rhinoceros, many species of which are on the verge of extinction.