Hercules beetle characteristics, habitat, feeding, reproduction

3302
Jonah Lester

The hercules beetle (Dynastes hercules) is an insect belonging to the Dynastinae subfamily. It is the largest species within its clade; the body of the male can reach 17.5 centimeters, including the horns.

This species shows a notorious sexual dimorphism. The male stands out because it has two large horns, one thoracic and the other cephalic. These structures are absent in the female. In addition, the male is black, with yellow, green or black elytra. As for the female, it is dark brown, with the lower end of the elytra olive green or yellow.

Anaxibia [CC BY-SA (https://creativecommons.org/licenses/by-sa/3.0)].

This species is endemic to the rainforests of South America, Central America, and the Lesser Antilles. In these regions it inhabits oak forests, rainforests and lauráceas forests.

It is a herbivorous animal, which, in the larval stage, feeds on decomposed wood, while in adulthood, its diet is based on fruits.

Article index

  • 1 General characteristics
    • 1.1 - Size
    • 1.2 - Coloring
    • 1.3 - Sexual dimorphism
    • 1.4 - The horns
  • 2 Moisture and color changes
    • 2.1 Special features
  • 3 Conservation status
  • 4 Habitat and distribution
    • 4.1 Habitat
  • 5 Taxonomy
  • 6 Food
  • 7 Digestive system
    • 7.1 Stomode
    • 7.2 Mesenteron
    • 7.3 Proctodement
  • 8 Playback
    • 8.1 Development phases
  • 9 Behavior
  • 10 References 

General characteristics

The body of the Dynastes hercules It is divided into three parts: the head, the thorax and the abdomen. However, there is a prothorax, where the elytra are found. These structures correspond to the front wings of the insect, which are hardened and thickened, forming a kind of protective layer..

In this way, the body seems to be divided into a front part (head and prothorax) and a rear part, under the elytra.

- Size

The hercules beetle is one of the largest in the Dynastinae subfamily. The adult size ranges from 50 to 85 millimeters in length, not including the horns. As for the width, it ranges between 29 and 42 millimeters. However, some males can measure up to 175 millimeters, including the horns..

The size of the horn is variable, since it depends on various factors. These include physiological conditions, stress, nutrition, and exposure to parasites. However, in all cases the thoracic horn is much longer than the cephalic.

In the following video you can see the size of a male of this species and how it moves its wings to fly:

- Coloration

The male's body is black, except for the elytra, which have iridescent olive green hues and black spots. As for the female, it has a dark brown body. Its elytra are usually black, but some may have the last quarter olive green or yellowish.

The young have pale yellow coloration, with black spots on the sides. The head is completely black.

- Sexual dimorphism

This species has a marked sexual dimorphism. The main characteristic that distinguishes the male from the female is his antlers. This has a thoracic horn, which arises from the thorax, and another cephalic, which arises from the head. For its part, the female lacks these structures.

- The horns

The thoracic horn has a tooth on each side, which is generally close to the base of this structure..

As for the cephalic horn, the adult male has a tooth, located at the distal end. Also, it has denticles, whose number can vary between 1 and 5. In some cases, these could merge into one..

Features

A group of researchers studied the function of horns in beetles. As a result, there was no evidence that females chose their mate based on the shape and size of the male's horns..

Based on this, the experts raised the hypothesis that relates the evolution of this structure with the fighting capacity of the animal. In this sense, the thoracic and cephalic horns of the Dynastes hercules form tweezers. These are used by the beetle during fights with other males..

With the antlers, he lifts and squeezes the opponent, and then throws him to the ground. In addition, the CT scan verifies that the horns of the rhinoceros beetle have an elliptical cross-sectional shape..

This characteristic maximizes the ability to take and dislodge the opponent, during the fierce fight that males sustain for access to a female in heat..

On the other hand, the stiffness and strength of the horns is a response to the combat load to which they are subjected. In this way, the morphological structure of these weapons is perfectly adapted to the functional demands of the fight of this species..

In the following video you can see the development of this species from larva to adult:

Moisture and color changes

The coloration of the male can have variations, depending on the degree of humidity that exists in the environment where it is found.

Thus, in a dry atmosphere, the elytra of the hercules beetle are olive green or yellowish in color. These turn black when humidity levels rise considerably.

The mechanism that triggers this change in tonality is related to the complex microstructure of the elite. In this sense, the greenish coloration originates in a porous layer, which is located 3 μm below the surface of the cuticle..

This cover is transparent and has three-dimensional photonic crystal structures. In its composition, there is a complex network of filaments, arranged parallel to the surface of the cuticle.

When the environment is dry, the holes in the layer, which are nanometric in size, are filled with air. However, when the humidity is high, these empty spaces fill with water. Thus, the variation in the refractive index, in relation to the level of humidity, causes the change in color of the elytra.

Special features

According to research carried out by experts, in the event that the hercules beetle accidentally loses an elytra, it continues to present variations in color, in response to changes in environmental humidity levels..

On the other hand, if a small area of ​​the elytra is subjected to higher humidity, the local color change occurs..

State of conservation

Currently, there are no data indicating the state of conservation of the Dynastes hercules. This is due to the lack of information on changes in population density. Similarly, studies related to the nature of its habitat are very scarce..

However, its natural habitat, the rainforest, is threatened by climate change and deforestation. In addition, the hercules beetle is sold as a pet in some regions, especially Japan..

These factors can affect the populations of this species, causing its notable decrease.

Habitat and distribution

The Dynastes hercules it is distributed from the southern zone of Mexico to Bolivia. Within this range, this species extends from the Pacific Ocean to the eastern area of ​​the Brazilian Amazon..

Thus, its habitat includes Central America, the Amazon of Colombia, the Pacific coast, western Venezuela, Ecuador, central Bolivia, and Brazil. Also, lives in the islands of Dominica and Guadeloupe.

Habitat

The hercules beetle is found in a variety of habitats, including rainforests, montane tropical forests, and lowlands. In addition, in the sub-Andean region it prefers the laurel forests and oak forests.

Due to the nature of this species, it is necessary that the environment possesses some peculiarities, such as trees with thick trunks that are in a state of decomposition..

In this sense, the larva of the Dynastes hercules, like other beetles, it lives in decayed wood. Because the animal in this stage is large, since it grows more than 15 centimeters and weighs around 140 grams, it needs to have trunks of an adequate circumference in its habitat, where it can continue its evolution..

The adult species is capable of flight, however, it is generally found on the understory or undergrowth floor. Thus, this beetle prefers those areas that retain moisture permanently.

Also, the hercules beetle requires a habitat that provides it with an abundance of fruits, which once fallen to the ground, it uses to feed..

In the following video you can see the habitat of this species and the fight between two males:

Taxonomy

-Animal Kingdom.

-Subkingdom: Bilateria.

-Superfilum: Ecdysozoa.

-Phylum: Arthropoda.

-Subphilum: Hexapoda.

-Class: Insecta.

-Subclass: Pterygota.

-Infraclass: Neoptera.

-Superorder: Holometaball.

-Order: Coleoptera.

-Suborder: Polyphaga.

-Infraorder: Scarabeiformia.

-Superfamily: Scarabaeoidea.

-Family: Scarabaeidae.

-Subfamily: Dynastinae.

-Genre: Dynastes.

-Species: Dynastes hercules.

Subspecies:

Dynastes hercules ecuatorianus.

Dynastes hercules trinidadensis.

Dynastes hercules hercules.

Dynastes hercules takakuwai.

Dynastes hercules lichyi.

Dynastes hercules septentrionalis.

Dynastes hercules morishimai.

Dynastes hercules reidi.

Dynastes hercules occidentalis.

Dynastes hercules paschoali.

Feeding

The hercules beetle is a herbivorous animal. Because a metamorphosis process occurs in this species, each of the stages has its own nutritional requirements.

Thus, the larva obtains the nutrients from the wood in a state of decomposition, preferring the trees of the families Chrysobalanaceae, Phyllanthaceae and Fabaceae..

The adult of this species usually feeds on fruits that have fallen to the ground and are decomposed. Experts have observed these beetles consuming mangoes and bananas.

When the insect is about to eat the fruit, it first pierces the skin with its mouth. Then, it begins to chew the pulp, which is soft, so it is easy to process.

Digestive system

The digestive system in the hercules beetle, as in other insects, is a duct. This extends from the mouth and ends at the anus. This system is divided into three areas: the stomodeum, mesentery and proctodeum..

Stomode

The inside of this tube is covered by a thick membrane, which has folds and projections. In the anterior part is the mouth. In this are the mouthparts, which participate in the process of chewing food.

In the stomodeum, the pharynx, esophagus, crop, proventricles and stomodeal valve are differentiated. This is responsible for regulating the passage of digestive juices and food to the mesentery.

Mesentery

The midgut, as this part of the digestive system is also known, is an elongated sac. The epithelium that covers it is very thick, presenting an irregular surface and finger-shaped projections. However, the muscle layer that surrounds it is thinner than that of the stomodeum..

As for the epithelial cells it contains, they are responsible for secreting a thin membrane, composed of protein and chitin. This fulfills a double function, first, it prevents the food consumed from coming into contact with the epithelial cells..

In addition, due to its permeability, it allows the passage of enzymes to the intestine and at the same time facilitates the entry into the body of organic compounds, a product of digestion..

Proctodeus

This final part of the digestive system ends in the anus and is divided into the foregut and rectum..

Reproduction

The hercules beetle reaches sexual maturity between 15 and 22 months. Like all of its family, this species goes through a complete metamorphosis. Thus, it has an egg stage, a larval, pupal and adult stage..

In this species, reproduction is sexual. Generally, the female initiates contact, secreting pheromones. Thus, the male can follow the scent trail and find it. Males compete with each other for the right to join the female.

In these battles, the male uses his horns to try to grab and subdue the opponent. When he does, he picks it up and then drops it abruptly. This can happen several times, until the male withdraws

The victor wins the opportunity to copulate with the female. A male can mate with several females, but they only mate to reproduce. After copulation, the gestation period begins, which lasts about 30 days.

Development phases

The female of the Dynastes hercules can lay up to 100 eggs. This is done on decayed wood or on the ground. Once these hatch, it takes 12-18 months for the larva to develop into a pupa. This lasts from 2 to 3 months developing, to later emerge as an adult.

Behaviour

The hercules beetle has nocturnal habits. At night it goes out in search of fruits, while during the day it lives under the leaf litter.

As for communication, it is usually a combination of the sense of sight, chemoreception and mechanical perception. In addition, experts point out that this beetle has the ability to detect vibrations.

When the Dynastes hercules feels threatened, it can create a loud sound, similar to a snort. He does this by rapidly vibrating his abdomen against his elite. On the other hand, this species frequently hides among the fallen leaves, to avoid being seen by predators..

Also, the adult produces an unpleasant odor. This is secreted in dangerous situations, with the intention of discouraging the predator that tries to capture it to eat it..

References

  1. Wikipedia (2020). Hercules beetle. Recovered from en.wikipedia.org.
  2. Oliver Keller, Ronald D. Cave (2016). Hercules beetle. Recovered from entnemdept.ufl.edu.
  3. Kulikowski, A. (2014). Dynastes hercules. Animal Diversity Web. Recovered from animaldiversity.org.
  4. Anna Toussaint (2015). Dynastes hercules (Hercules Beetle). Recovered from sta.uwi.edu.
  5. Matthew R. Moore (2006). Dynastes hercules (Linnaeus, 1758). Recovered from unsm-ento.unl.edu.
  6. Jen-Pan Huang (2017). The hercules beetles (subgenus Dynastes, genus Dynastes, Dynastidae): A revisionary study based on the integration of molecular, morphological, ecological, and geographic analyzes. Recovered from pdfs.semanticscholar.org.
  7. Marcia Malory (2014). Study shows rhinoceros beetle horns evolved to accommodate species-specific fighting styles. Recovered from phys.org.
  8. Miguel Ángel Alonso-Zarazaga (2020). Insect class. Order Coleoptera. Recovered from sea-entomologia.org.

Yet No Comments