The titan beetle (''Titanus giganteus'') is a

Neotropical The Neotropical realm is one of the eight biogeographic realms constituting Earth's land surface. Physically, it includes the tropical terrestrial ecoregions of the Americas and the entire South American temperate zone. Definition In biogeogra ...

longhorn beetle The longhorn beetles (Cerambycidae), also known as long-horned or longicorns (whose larvae are often referred to as roundheaded borers), are a large family of beetles, with over 35,000 species described. Most species are characterized by Antenn ...

, the sole

species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...

in the

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

''Titanus'', and one of the largest known

beetle Beetles are insects that form the Taxonomic rank, order Coleoptera (), in the superorder Holometabola. Their front pair of wings are hardened into wing-cases, elytra, distinguishing them from most other insects. The Coleoptera, with about 40 ...

s, as well as one of the largest known insects, at over in length. Adult titan beetles only live for a few weeks, and protect themselves from predators with their sharp spines and powerful jaws.

Distribution and habitat

The titan beetle is native to

tropical rainforest Tropical rainforests are dense and warm rainforests with high rainfall typically found between 10° north and south of the Equator. They are a subset of the tropical forest biome that occurs roughly within the 28° latitudes (in the torrid zo ...

s throughout

South America South America is a continent entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a considerably smaller portion in the Northern Hemisphere. It can also be described as the southern Subregion#Americas, subregion o ...

, including

Venezuela Venezuela, officially the Bolivarian Republic of Venezuela, is a country on the northern coast of South America, consisting of a continental landmass and many Federal Dependencies of Venezuela, islands and islets in the Caribbean Sea. It com ...

Colombia Colombia, officially the Republic of Colombia, is a country primarily located in South America with Insular region of Colombia, insular regions in North America. The Colombian mainland is bordered by the Caribbean Sea to the north, Venezuel ...

Ecuador Ecuador, officially the Republic of Ecuador, is a country in northwestern South America, bordered by Colombia on the north, Peru on the east and south, and the Pacific Ocean on the west. It also includes the Galápagos Province which contain ...

Peru Peru, officially the Republic of Peru, is a country in western South America. It is bordered in the north by Ecuador and Colombia, in the east by Brazil, in the southeast by Bolivia, in the south by Chile, and in the south and west by the Pac ...

, the

Guianas The Guianas, also spelled Guyanas or Guayanas, are a geographical region in north-eastern South America. Strictly, the term refers to the three Guianas: Guyana, Suriname, and French Guiana, formerly British Guiana, British, Surinam (Dutch colo ...

, and north-central

Brazil Brazil, officially the Federative Republic of Brazil, is the largest country in South America. It is the world's List of countries and dependencies by area, fifth-largest country by area and the List of countries and dependencies by population ...

. While the Titan Beetle is most generally associated with the

Amazon Rainforest The Amazon rainforest, also called the Amazon jungle or Amazonia, is a Tropical and subtropical moist broadleaf forests, moist broadleaf tropical rainforest in the Amazon biome that covers most of the Amazon basin of South America. This basin ...

, it may also be found in other parts of South America if ecological conditions are favorable. This comprises sections of the Atlantic Forest in Brazil, the Orinoco Basin in Venezuela, and the Chocó-Darién region in Colombia. These beetles are primarily found in old-growth forests with plenty of rotting wood, which serves as their principal food supply. They can, however, be found in secondary forests and disturbed habitats where sufficient circumstances for survival exist. Despite their broad distribution throughout South America, the titan beetle is secretive and rarely seen due to its nocturnal habits and cryptic behavior. As a result, thorough surveys and research are required to acquire a better knowledge of its distribution throughout its range, as well as population dynamics within various forest habitats. However, like many other species that live in tropical rainforests, the titan beetle is threatened by habitat degradation, deforestation, and climate change, all of which can have a substantial influence on its distribution and population levels. Conservation activities focused at maintaining their natural habitats are therefore critical for assuring their continued survival.

Anatomy and physiology

''Titanus giganteus'' is known for being one of the largest beetles, spanning over . Though great in size, studies have shown that within the family

Cerambycidae The longhorn beetles (Cerambycidae), also known as long-horned or longicorns (whose larvae are often referred to as roundheaded borers), are a large family of beetles, with over 35,000 species described. Most species are characterized by anten ...

, they have exceptionally short hind wings. Additionally, the hind wings are not present in females, indicating that they are incapable of flight. Titan beetles have

compound eyes A compound eye is a visual organ found in arthropods such as insects and crustaceans. It may consist of thousands of ommatidia, which are tiny independent photoreception units that consist of a cornea, lens, and photoreceptor cells which distin ...

(an eye consisting of an array of numerous small visual units), with hundreds of hexagonal facets covering the central region of the eye and the periphery being covered by pentagonal or squares. Unique to ''Titanus giganteus'', there exists a distinct row of

proprioceptive Proprioception ( ) is the sense of self-movement, force, and body position. Proprioception is mediated by proprioceptors, a type of sensory receptor, located within muscles, tendons, and joints. Most animals possess multiple subtypes of propri ...

hairs that is visible on the anterior edge of the

prothorax The prothorax is the foremost of the three segments in the thorax of an insect, and bears the first pair of legs. Its principal sclerites (exoskeletal plates) are the pronotum (dorsal), the prosternum ( ventral), and the propleuron (lateral) on ...

. The hairs have a mechanoreceptive function, detecting changes to the body surface to assess the environment. Their antennae have sensilla which provide sensory information about the environment. There are different types of sensilla, e.g. coeloconic sensilla and sensilla trichoidea, detecting different stimuli. The reproductive system of the titan beetle is very similar to other species within the subfamily

Prioninae The Prioninae are a subfamily of Cerambycidae (long-horned beetles). They are typically large (25–70 mm) and usually brown or black. The males of a few genera sport large Mandible (arthropod), mandibles that are used in fights with other ...

, with the pupal testis consisting of 12 to 15 lobes each containing 15 follicles. One unusual characteristic regarding the reproductive anatomy of titan beetles is the variation in follicle size. Titan beetles with larger follicles were seen to have greater rates of

spermatogenesis Spermatogenesis is the process by which haploid spermatozoa develop from germ cells in the seminiferous tubules of the testicle. This process starts with the Mitosis, mitotic division of the stem cells located close to the basement membrane of ...

. The mechanism for such variation is unknown.

Size

Insect size is constrained by the amount of air that can be supplied via their

respiratory system The respiratory system (also respiratory apparatus, ventilatory system) is a biological system consisting of specific organs and structures used for gas exchange in animals and plants. The anatomy and physiology that make this happen varies grea ...

. The respiratory system of insects is different from

mammals A mammal () is a vertebrate animal of the class Mammalia (). Mammals are characterised by the presence of milk-producing mammary glands for feeding their young, a broad neocortex region of the brain, fur or hair, and three middle e ...

, as gas exchange involves tracheal tubes delivering oxygen directly to tissues throughout the beetle's body, instead of having oxygen carried by blood. The constraint on the diffusion of oxygen into the tracheal system limits the maximum body size attainable, as there will be a point where some tissues in the body will not receive oxygen at all.

Microbiome

Because adult titan beetles do not feed, it is interesting that the very narrow

gut microbiota Gut microbiota, gut microbiome, or gut flora are the microorganisms, including bacteria, archaea, fungi, and viruses, that live in the digestive tracts of animals. The gastrointestinal metagenome is the aggregate of all the genomes of the g ...

show no activity of

proteases A protease (also called a peptidase, proteinase, or proteolytic enzyme) is an enzyme that catalyzes proteolysis, breaking down proteins into smaller polypeptides or single amino acids, and spurring the formation of new protein products. They do ...

, despite there being recorded activity of digestive

amylase An amylase () is an enzyme that catalysis, catalyses the hydrolysis of starch (Latin ') into sugars. Amylase is present in the saliva of humans and some other mammals, where it begins the chemical process of digestion. Foods that contain large ...

and

lipase In biochemistry, lipase ( ) refers to a class of enzymes that catalyzes the hydrolysis of fats. Some lipases display broad substrate scope including esters of cholesterol, phospholipids, and of lipid-soluble vitamins and sphingomyelinases; howe ...

activity. Digestive amylase, lipase, and protease in human and other animal organisms are responsible for breaking down food proteins into

amino acids Amino acids are organic compounds that contain both amino and carboxylic acid functional groups. Although over 500 amino acids exist in nature, by far the most important are the Proteinogenic amino acid, 22 α-amino acids incorporated into p ...

for absorption. There is no fat surrounding the gut of ''T. giganteus'', which differs from other

. It is suggested that the

metabolic rate Metabolism (, from ''metabolē'', "change") is the set of life-sustaining chemical reactions in organisms. The three main functions of metabolism are: the conversion of the energy in food to energy available to run cellular processes; the co ...

could differ, such that adult titan beetles exhaust all of their fat reserves faster than related beetles. Liquid chromatography-mass spectrometry analysis indicated that 70 percent of the lipids were

triacylglycerols A triglyceride (from '' tri-'' and '' glyceride''; also TG, triacylglycerol, TAG, or triacylglyceride) is an ester derived from glycerol and three fatty acids. Triglycerides are the main constituents of body fat in humans and other vertebrates a ...

. These lipids were found only in the flight muscles, in which the fat reserves were used to provide energy for muscle activity. Within the triacylglycerols, it was found

oleic acid Oleic acid is a fatty acid that occurs naturally in various animal and vegetable fats and oils. It is an odorless, colorless oil, although commercial samples may be yellowish due to the presence of impurities. In chemical terms, oleic acid is cl ...

is the most abundant.

Ecology and behavior

Diet

Even though the Cerambycidae family is known to utilize a plant diet for sustenance, the Prioninae subfamily does not accept any food with the exception of water. Reflected in their anatomy, titan beetles do not have all the

digestive enzyme Digestive enzymes take part in the chemical process of digestion, which follows the mechanical process of digestion. Food consists of macromolecules of proteins, carbohydrates, and fats that need to be broken down chemically by digestive enzymes ...

s and fat reserves needed to consume food on a daily basis. Rather when the titan beetles are

larva A larva (; : larvae ) is a distinct juvenile form many animals undergo before metamorphosis into their next life stage. Animals with indirect development such as insects, some arachnids, amphibians, or cnidarians typically have a larval phase ...

e, they ingest dead

wood Wood is a structural tissue/material found as xylem in the stems and roots of trees and other woody plants. It is an organic materiala natural composite of cellulosic fibers that are strong in tension and embedded in a matrix of lignin t ...

and

plant Plants are the eukaryotes that form the Kingdom (biology), kingdom Plantae; they are predominantly Photosynthesis, photosynthetic. This means that they obtain their energy from sunlight, using chloroplasts derived from endosymbiosis with c ...

s infested by

fungi A fungus (: fungi , , , or ; or funguses) is any member of the group of eukaryotic organisms that includes microorganisms such as yeasts and mold (fungus), molds, as well as the more familiar mushrooms. These organisms are classified as one ...

. This initial caloric intake is meant to last the lifetime of the beetle. Their dietary habits as larvae contribute to the recycling of dead plants in the

ecosystem An ecosystem (or ecological system) is a system formed by Organism, organisms in interaction with their Biophysical environment, environment. The Biotic material, biotic and abiotic components are linked together through nutrient cycles and en ...

, converting decayed matter into

humus In classical soil science, humus is the dark organic matter in soil that is formed by the decomposition of plant and animal matter. It is a kind of soil organic matter. It is rich in nutrients and retains moisture in the soil. Humus is the Lati ...

. The subfamily Prioninae of titan beetles are known as gall-inducing insects.

Gall Galls (from the Latin , 'oak-apple') or ''cecidia'' (from the Greek , anything gushing out) are a kind of swelling growth on the external tissues of plants. Plant galls are abnormal outgrowths of plant tissues, similar to benign tumors or war ...

s, which are abnormal growths in plants, are a byproduct of plant consumption. These galls are used as nests for many insects, including beetles.

Mating

Because of the short life span of the titan beetle, little is concretely known about their

mating In biology, mating is the pairing of either opposite-sex or hermaphroditic organisms for the purposes of sexual reproduction. ''Fertilization'' is the fusion of two gametes. '' Copulation'' is the union of the sex organs of two sexually repr ...

behavior. It is, however, known that titan beetles locate their mates by sensing

pheromones A pheromone () is a secreted or excreted chemical factor that triggers a social response in members of the same species. Pheromones are chemicals capable of acting like hormones outside the body of the secreting individual, to affect the behavi ...

. In the field of

coleopterology Coleopterology (from Coleoptera and Greek , ''-logia'') is the scientific study of beetles, a branch of entomology. Practitioners are termed coleopterists and form groups of amateurs and professionals for business and pleasure. Among these is Th ...

the larvae of titan beetles have yet to be found. This makes witnessing the life cycle and reproduction of titan beetles very difficult.

Gallery

File:Titanus giganteus specimens.jpg, ''Titanus giganteus'' beetles for sale at international meeting of entomologists in Prague File:Titanus giganteus MHNT dos.jpg, ''Titanus giganteus'' male File:Cerambycidae - Titanus giganteus-001.JPG, ''Titanus giganteus'' at the Montréal Insectarium File:Titan beetle (Titanus giganteus) found by Jean NICOLAS (10331669783).jpg

References

External links

* *
''Titanus giganteus'' pictures at Bio-Foto.com

Video clip of the Titan beetle from Life in the Undergrowth

Giant beetle visits Oxford University

BBC news article with photograph

BBC article which covers the beetle's grubs

{{Taxonbar, from1=Q858284, from2=Q12092818 Prioninae Fauna of the Amazon Fauna of the Atlantic Forest Beetles of Brazil Arthropods of Colombia Invertebrates of Ecuador Invertebrates of French Guiana Insects of Peru Invertebrates of Venezuela Taxa named by Carl Linnaeus Beetles described in 1771