question: Why do ants carry dead ants back to the nest?
comment: Ants don't really have any understanding of why they are doing certain things, they're pretty much programmed to operate based on certain stimuli. Why did a fellow ant die? infected with a parasite? contagious bacteria or fungus? If the dead or dying ant is taken away from the next or where the colony is active, the lower the chance of it spreading the disease to it's nest mates. For example this is a video of parasitic fungus attacking ants. URL_1 For fun, look up some of the [theories]( URL_0 ) of why humans like Chanel #5, and a brain parasite.
passages: Necrophoresis is a behavior found in social insects – such as ants, bees, wasps, and termites – in which they carry the dead bodies of members of their colony from the nest or hive area. This acts as a sanitary measure to prevent disease or infection from spreading throughout the colony. Although any member of a colony can carry the bodies, it is usually done by designated 'undertakers'. Ant undertakers have a slightly altered development cycle, and are much more likely than other ants to handle corpse removal. They are not restricted to performing only this task, but they do exhibit different behavioral and movement patterns than other members of the colony, which assist them in this task. Non-undertaker ants may also remove dead bodies, but do so with much less consistency. Differentiating between dead and living insects is accomplished by detecting their chemical signature. Depending on the species, this can be communicated by either the absence of chemicals that are present when they are alive, or by those released in decaying corpses. Corpses will either be taken to a random point a certain distance away from the nest, or placed in a refuse pile closer to the nest, along with other waste. 
   The removal of corpses carrying infectious disease is crucial to the health of a colony. Efforts to eliminate colonies of fire ants, for instance, include introducing pathogens into the population, but this has limited efficacy where the infected insects are quickly separated from the population. However, certain infections have been shown to delay the removal of dead bodies or alter where they are placed. Although placing corpses farther away reduces the risk of infection, it also requires more energy. Burial and cannibalism are other recorded methods of corpse disposal among social insects. Termites have been shown to use burial when they cannot afford to devote workers to necrophoresis, especially when forming a new colony.
   BULLET::::- The corpses of group members killed by an infectious disease present a serious hazard to colony health (as in natural environments death from disease is much more common than death from old age): one mechanism that has evolved to help neutralize this risk is necrophoresis, the removal of corpses from the nest by workers. 'Refuse piles' or 'graveyards' are common features of ant colonies, and workers remove corpses (within the hour after death) to these piles after detecting death signatures in the cuticular hydrocarbon chemistry. Corpse deposition is biased towards downward slopes, which saves the corpse-transporting worker energy as well as preventing any rain washing the corpses back into the colony - necrophoretic behaviours are distinct from ant responses to foreign inanimate objects as corpses are transported further and quicker. By bringing corpses out of the nest the ultraviolet radiation in sunlight can kill emerging fungal spores; "Atta" transport corpses to special refuse chambers rather than into the external environment. "Temnothorax lichtensteini" ants remove the corpses of dead sisters as above, but bury newly-dead foreign corpses inside the nest - whilst one or a few individuals 'decide' to transport or bury a corpse, up to 25 workers are then involved in the undertaking of one corpse. Termites commonly bury and cannabalize corpses: when "C. formosanus" colonies are infected with "M. anisopliae", necrophagy is common when the proportion of dead individuals in an area was low (15%), but as mortality increased then so did burying behaviour up to 75%–80% mortality above which carcasses were too numerous for workers to bury and secondary rounds of "M. anisopliae" infection was possible. Termites do occasionally remove dead from the nest but this is uncommon (leaving the nest at all is rare); refuse chambers or piles/graveyards have not been observed. Research on undertaking behaviours in bees has concentrated on the honeybee ("Apis mellifera"): 1–2% of a colony are undertaker bees, specialized for corpse removal: they inspect corpses with their antennae before rapidly dropping them from the nest.
   In addition to defence against predators, ants need to protect their colonies from pathogens. Some worker ants maintain the hygiene of the colony and their activities include undertaking or "necrophory", the disposal of dead nest-mates. Oleic acid has been identified as the compound released from dead ants that triggers necrophoric behaviour in "Atta mexicana" while workers of "Linepithema humile" react to the absence of characteristic chemicals (dolichodial and iridomyrmecin) present on the cuticle of their living nestmates to trigger similar behaviour.
   In some parts of the world (mainly Africa and South America), large ants, especially army ants, are used as surgical sutures. The wound is pressed together and ants are applied along it. The ant seizes the edges of the wound in its mandibles and locks in place. The body is then cut off and the head and mandibles remain in place to close the wound. The large heads of the dinergates (soldiers) of the leafcutting ant "Atta cephalotes" are also used by native surgeons in closing wounds.
   During the battle against termites some of the ants get injured. The termite soldiers are able to bite off extremities or cling on to the ant body after their death.
   "Temnothorax unifasciatus" exhibit the altruistic behavior of social withdrawal, or “altruistic self-removal” whilst on the brink of death. Dying ants will leave their nest hours or in some cases days before their death. The behavior is exhibited both in the presence of fungal infection as well as when experimentally exposed to 95% CO2, causing the ants to die in the absence of an acting pathogen. This indicates that the ants are in fact behaving in an altruistic manner, rather than experiencing behavioral manipulation as a result of pathogen influence. The action is altruistic because it reduces the risk of infecting other ants in the colony. This in turn minimizes the risk of transferring the infection to kin and thus likely results in a higher inclusive fitness for the socially withdrawing individuals.
   Such is the strength of the ant's jaws that, in East Africa, they are used as natural, emergency sutures. Various East African indigenous tribal peoples (e.g. Maasai moran), when suffering from a gash in the bush, will use the soldiers to stitch the wound by getting the ants to bite on both sides of the gash, then breaking off the body. This use of ants as makeshift surgical staples creates a seal that can hold for days at a time, and the procedure can be repeated, if necessary, allowing natural healing to commence.
   Necrophoric behaviour occurs in the red imported fire ant. Workers discard uneaten food and other such wastes away from the nest. The active component was not identified, but the fatty acids accumulating as a result of decomposition were implicated and bits of paper coated with synthetic oleic acid typically elicited a necrophoric response. The process behind this behaviour in imported red fire ants was confirmed by Blum (1970): unsaturated fats, such as oleic acid, elicit corpse-removal behaviour. Workers also show differentiated responses towards dead workers and pupae. Dead workers are usually taken away from the nest, whereas the pupae may take a day for a necrophoric response to occur. Pupae infected by "Metarhizium anisopliae" are usually discarded by workers at a higher rate; 47.5% of unaffected corpses are discarded within a day, but for affected corpses this figure is 73.8%.
   "Cyclotorna monocentra" moths feed on meat ant broods. The larvae of these moths are parasites to leafhoppers and will move to meat ant colonies to complete their development, where they will proceed to consume the brood; the females lay many eggs near ant trails which are close to the leafhoppers tended by ants. Other observations show that the "Iphierga macarista" larvae are scavengers in meat ant nests, while "Sphallomorpha" beetles live in burrows near nests of meat ants, where the larvae capture and prey on workers passing by. The larvae of the spitfire sawfly and "Pseudoperga guerini" are able to regurgitate a fluid against the meat ant if they are getting attacked by them; depending on how much is regurgitated, an ant will either walk away and clean itself or become fatally affected by it. Lizards such as the thorny dragon, which is a sit and wait predator, consume meat ants, but other lizards which eat "Iridomyrmex" ants usually reject this species.
   BULLET::::- Social exclusion of infected individuals can also prevent intra-group transmission. When dampwood termites ("Z. angusticollis") come into contact with high densities of entamopathogenic fungal spores, they perform a whole-body "vibratory motor display" which induce others who are not in direct contact with the spores to flee, increasing their distance from the infected individual. In the eastern subterranean termite ("R. flavipes") infection with the same fungus also causes a vibratory alarm response; termites then aggregate around the infected individual and box it in, preventing it from moving to other areas of the colony; it is sometimes licked and bitten before subsequently being buried. Individual "Temnothorax unifasciatus" ants who are dying due to fungal infection, carbon dioxide poisoning or 'naturally' (of unknown cause in colonies which had not been experimentally manipulated) permanently leave the nest one to 50 hours before their death, altruistically ceasing all social interactions with nestmates and dying alone away from the colony. Some "Apis mellifera" workers are 'hygiene specialists'—they detect cells in the colony containing diseased or dead brood, uncap these cells and then remove the cell contents.
   BULLET::::- Similarly, individuals can inhibit parasite uptake by refraining from consuming infected conspecifics. Argentine ants ("Linepithema humile") and cornfield ants ("Lasius alienus") both detect chemical 'ant deterrent factors' adaptively produced by entamopathogenic bacteria and thus avoid infected corpses; "R. tibalis" doesn't cannibalize conspecifics infected with "M. anisopliae."
   Infected individuals and diseased corpses pose a particular risk for social insects because they can act a source of infection for the rest of the colony. As mentioned above, dead nestmates are typically removed from the nest to reduce the potential risk of disease transmission. Infected or not, ants that are close to death can also voluntarily remove themselves from the colony to limit this risk. Honeybees can actively drag infected nest mates out of the hive and may bar them from entering at all. "Hygienic behaviour" is the specific removal of infected brood from the colony and has been reported in both honeybees and ants. In honeybees, colonies have been artificially selected to perform this behavior faster. These "hygienic" hives have improved recovery rates following brood infections, as the earlier infected brood is removed, the less likely it is to have become contagious already. Cannibalism of infected nesmtates is an effective behaviour in termites, as ingested infectious material is destroyed by antimicrobial enzymes present in their guts. These enzymes function by breaking down the cell walls of pathogenic fungi, for example, and are produced both by the termite itself and their gut microbiota. If there are too many corpses to cannibalise, termites bury them in the nest instead. Like removal in ants and bees, this isolates the corpses to contain the pathogen, but does not prevent their replication. Some fungal pathogens (e.g. "Ophiocordyceps", "Pandora") manipulate their ant hosts into leaving the nest and climbing plant stems surrounding the colony. There, attached to the stem, they die and rain down new spores onto healthy foragers. To combat these fungi, healthy ants actively search for corpses on plant stems and attempt to remove them before they can release their spores
   A new ergate spends the first few days of its adult life caring for the queen and young. She then graduates to digging and other nest work, and later to defending the nest and foraging. These changes are sometimes fairly sudden, and define what are called temporal castes. An explanation for the sequence is suggested by the high casualties involved in foraging, making it an acceptable risk only for ants who are older and are likely to die soon of natural causes.
   BULLET::::- Some termites, such as "Globitermes sulphureus" and ants, such as "Camponotus saundersi" release a sticky secretion by fatally rupturing a specialized gland. This autothysis altruistically defends the colony at the expense of the individual insect. This can be attributed to the fact that ants share their genes with the entire colony, and so this behaviour is evolutionarily beneficial (not necessarily for the individual ant but for the continuation of its genetic make-up).
   The red harvester ant "Pogonomyrmex californicus" has been widely used by natives of Southern California and Northern Mexico for hundreds of years in ceremonies conducted to help tribe members acquire spirit helpers through hallucination. During the ritual, young men are sent away from the tribe and consume large quantities of live, unmasticated ants under the supervision of an elderly member of the tribe. Ingestion of ants should lead to a prolonged state of unconsciousness, where dream helpers appear and serve as allies to the dreamer for the rest of his life.
  
  Section::::Symbolic uses.:In art.
   The "M. multispinosus" is most known for its trait of attaching onto longhorn crazy ants. Once it has attached onto the ants pupa it begins to drain the ant of its haemolymph. The haemolymph is the roughly equivalent of a humans blood. It is the fluid that flows through the ant. "M. multispinosus" doesn't just suck the ants internal fluids, but also begins to consume the internal tissue within the ant's pupa. The host ants that are sought out by "M. multispinosus"are the worker ants. This is due to making sure the reproductive portions of the ant colonies are unaffected so the number of hosts for the parasite to infect is always growing. Regardless, the infection and death of worker ants by "M. multispinosus"can prove deadly for ant colonies if the parasite is present in large numbers.
   Attention to the dead is not unique to elephants or chimpanzees. Dolphins have been known to stay with recently deceased members of their pod for several days, preventing divers from getting close. However, the reasons for this remain obscure. While scientists can observe their actions, the thought processes that motivate them are beyond current study.
  
  Section::::Relevance to the study of early modern humans.
   The changes in the behavior of the infected ants are very specific, giving rise to the popular term "zombie ants", and are tuned for the benefit of the fungus. The spores of the fungus attach to and eventually break through the ant's exoskeleton using mechanical pressure and enzymes. Yeast stages of the fungus spread in the ant's body and presumably produce compounds that affect the ant's hemocoel, using the evolutionary trait of an extended phenotype to manipulate the behavioral patterns exhibited by the ant. An infected ant exhibits irregularly timed full-body convulsions that dislodge it to the forest floor. The ant climbs up the stem of a plant and uses its mandibles with abnormal force to secure itself to a leaf vein, leaving dumbbell-shaped marks on it. The ants generally clamp to a leaf's vein at a height of 25 cm above the forest floor, on the northern side of the plant, in an environment with 94–95% humidity and temperatures between . Infections may lead to 20 to 30 dead ants per square meter. "Each time, they are on leaves that are a particular height off the ground and they have bitten into the main vein [of a leaf] before dying." When the dead ants are moved to other places and positions, further vegetative growth and sporulation either fails to occur or results in undersized and abnormal reproductive structures.
   Oleic acid has been identified as the compound released from dead ants that triggers necrophoric behaviour in genus "Myrmica", however "M. scabrinodis scabrinodis" occasionally respond by engaging in anthropophagy. Males in this species react to the absence of characteristic chemicals (dolichodial and iridomyrmecin) present on the cuticle of their living nestmates to trigger a similar response. About 12%, 16%, and 4% of their faecal volume in spring, summer, and autumn, respectively, is composed of material from this behaviour.
   Workers place small pieces of resin over the entrance holes to prevent ants and the hosts from entering the entrance tube during the raid. Once the raid is complete, they remove the seal.
  
  Section::::Human importance.
  
  Section::::Human importance.:Production.
   Infected ants develop bright red gasters, tend to be more sluggish, and walk with their gasters in a conspicuous elevated position. According to Jonathan (2011), infected gasters had 57% more mass, but 37% lower metabolic rates, compared to uninfected gasters. These changes likely cause frugivorous birds to mistake the infected ants for berries and eat them. Increased reddening coincides with a shift in ant behavior that includes foraging outside the nest, thus increasing the probability of consumption by a duped bird.
  
  Section::::Morphology.
   Workers use several different strategies to deal with their dead, including burying, cannibalism, and avoiding a corpse altogether. To avoid pathogens, termites occasionally engage in necrophoresis, in which a nestmate carries away a corpse from the colony to dispose of it elsewhere. Which strategy is used depends on the nature of the corpse a worker is dealing with (i.e. the age of the carcass).
  
  Section::::Behaviour and ecology.:Relationship with other organisms.
   The few studies of the mutualism between "M. schumanni"–"D. hirsuta" have incorrectly concluded that these clearings are formed by allelopathy on the part of "D. hirsuta". It was established that worker ants were injecting leaves with formic acid, a toxin commonly produced in ant species, and the plants started to die within 24 hours. Lemon ants are the only known insect to use formic acid as a herbicide.
   Sniffles has made several machines to catch the Ant Family, but they usually backfire on him. In some episodes, Sniffles has been very obsessive when trying to eat them. He managed to eat ants in "A Hard Act to Swallow" and "Blast from the Past", but in "A Hard Act to Swallow", the other ants rescue the eaten ant. In order to escape, they tie up one of Sniffles' blood vessels, causing his heart to explode and his chest to rupture. The only time Sniffles got away with eating an ant without being killed was in Blast from the Past, where to stop Cuddles, Giggles, Lumpy, and Toothy from dying he went back to prehistoric times to make sure everything was perfect. When he was leaving, he saw an ant on a fern and ate it. Prehistoric Sniffles saw this and he ate an ant too. Liking it, this started the conflict between ants and anteaters. The present version of the Ant Family, however, have not yet died.
  
presuppositions: Ants carry dead ants back to the nest. Ants carry dead ants back to the nest.
corrections: Ants will carry dead ants AWAY from the nest to prevent the spread of potential disease.  Ants carry dead ants away from the nest so any disease the dead ant has is not spread to other ants.
raw_presuppositions: Ants carry dead ants back to the nest. Ants carry dead ants back to the nest.
raw_corrections: Ants will carry dead ants AWAY from the nest to prevent the spread of potential disease.  Ants carry dead ants away from the nest so any disease the dead ant has is not spread to other ants.