Abstract:Haberl W. 1998. The behaviour of licking the everted rectum in shrews (Soricidae, Insectivora). Acta Theriologica: 43: 113-120.The behaviour of licking the everted rectum in shrews, hitherto referred to as "coprophagy" or "refection" is reviewed. To avoid confusion with "true" faeces-eating, it is proposed to persistently use the descriptive term "rectum-licking" when referring to this phenomenon. The behaviour is characterized by the animal everting the rectum by a series of abdominal contractions and licking… Show more
“…Shrews, small carnivores, have been observed to lick the everted rectum and this behaviour has been referred to as 'refection' or 'coprophagy'. However, it is not appropriate to refer to it as such because it has not been ascertained what was actually licked, which in most cases is probably not faeces (Hirakawa & Haberl, 1998). Haga (1960) reported that the Northern Pika (Ochotona hyperborea) has two types of faeces: one is a deep green, spherical, hard but friable faex which is defecated mostly during the daytime; the other is a blackish-coloured soft faex, coated with a gelatinous and viscous substance.…”
Section: Reingestion In Non-leporid Herbivoresmentioning
Leporids have long been known to reingest soft faeces. However, it was recently found that they regularly reingest hard faeces, too. During the daytime, both soft and hard faeces are defecated and all of the faeces are reingested. Excreted at night are the hard faeces, which are normally discarded but reingested in starvation. The separation mechanism in the proximal colon, which diverts fine particles into the caecum and thus only passes large food particles, produces hard faeces. When the mechanism ceases acting, fermented caecal materials are excreted as soft faeces. The reingestion of soft faeces, rich in vitamins and microbial proteins, is physiologically imperative. Hard faeces are basically a refuse, but their thorough mastication at reingestion reduces poorly digestible large particles to fine ones good for fermentation. The regular reingestion of daytime hard faeces thus promotes food digestibility. The temporary use of night-time hard faeces allows leporids to do without food for some time. It thus gives leporids behavioural flexibility and thereby an ecological advantage. Reingestion is also known in other small-to medium-sized herbivores, which are all caecal fermenters. Morphological differentiation between faeces is reported only in larger species, but all ingested faeces are found to be richer in nutrients than discarded ones. Thus a separation mechanism is probably present in all reingesting species. Reingestion activity is deeply related to other behavioural and physiological traits of small mammalian herbivores, hence its study is important to understanding of their ecology and biology. Leporids are the largest of the reingesting species except for the semi-aquatic Coypu, and reingestion by leporids is certainly the most sophisticated. This development of a reingestion-involved digestive system has probably brought them to their present niche, as terrestrial medium-sized generalist mammalian herbivores, and consequently made their characteristic hide-and-run lifeforms by exposing them to a strong predation pressure.
“…Shrews, small carnivores, have been observed to lick the everted rectum and this behaviour has been referred to as 'refection' or 'coprophagy'. However, it is not appropriate to refer to it as such because it has not been ascertained what was actually licked, which in most cases is probably not faeces (Hirakawa & Haberl, 1998). Haga (1960) reported that the Northern Pika (Ochotona hyperborea) has two types of faeces: one is a deep green, spherical, hard but friable faex which is defecated mostly during the daytime; the other is a blackish-coloured soft faex, coated with a gelatinous and viscous substance.…”
Section: Reingestion In Non-leporid Herbivoresmentioning
Leporids have long been known to reingest soft faeces. However, it was recently found that they regularly reingest hard faeces, too. During the daytime, both soft and hard faeces are defecated and all of the faeces are reingested. Excreted at night are the hard faeces, which are normally discarded but reingested in starvation. The separation mechanism in the proximal colon, which diverts fine particles into the caecum and thus only passes large food particles, produces hard faeces. When the mechanism ceases acting, fermented caecal materials are excreted as soft faeces. The reingestion of soft faeces, rich in vitamins and microbial proteins, is physiologically imperative. Hard faeces are basically a refuse, but their thorough mastication at reingestion reduces poorly digestible large particles to fine ones good for fermentation. The regular reingestion of daytime hard faeces thus promotes food digestibility. The temporary use of night-time hard faeces allows leporids to do without food for some time. It thus gives leporids behavioural flexibility and thereby an ecological advantage. Reingestion is also known in other small-to medium-sized herbivores, which are all caecal fermenters. Morphological differentiation between faeces is reported only in larger species, but all ingested faeces are found to be richer in nutrients than discarded ones. Thus a separation mechanism is probably present in all reingesting species. Reingestion activity is deeply related to other behavioural and physiological traits of small mammalian herbivores, hence its study is important to understanding of their ecology and biology. Leporids are the largest of the reingesting species except for the semi-aquatic Coypu, and reingestion by leporids is certainly the most sophisticated. This development of a reingestion-involved digestive system has probably brought them to their present niche, as terrestrial medium-sized generalist mammalian herbivores, and consequently made their characteristic hide-and-run lifeforms by exposing them to a strong predation pressure.
“…Whether the licking of the everted hindgut observed in many shrew species [e.g. 75] has a similar function remains to be investigated. Figure 1Marker excretion patterns for a solute (liquid)-associated and a particulate marker in species with separation mechanism-based coprophagy and corresponding secondary marker excretion peaks (arrows) indicative of repeated marker ingestion via coprophagy.…”
Section: Gastrointestinal Tract Evolution In Mammalsmentioning
Both teeth and the digestive tract show adaptations that are commonly interpreted in the context of trophic guilds—faunivory, herbivory and omnivory. Teeth prepare food for the digestive tract, and dental evolution focuses on increasing durability and functionality; in particular, size reduction of plant particles is an important preparation for microbial fermentative digestion. In narratives of digestive adaptations, microbes are typically considered as service providers, facilitating digestion. That the majority of ‘herbivorous’ (and possibly ‘omnivorous’) mammals display adaptations to maximize microbes' use as prey—by harvesting the microbes multiplying in their guts—is less emphasized and not reflected in trophic labels. Harvesting of microbes occurs either via coprophagy after separation from indigestible material by a separation mechanism in the hindgut, or from a forestomach by a ‘washing mechanism’ that selectively removes fines, including microbes, to the lower digestive tract. The evolution of this washing mechanism as part of the microbe farming niche opened the opportunity for the evolution of another mechanism that links teeth and guts in an innovative way—the sorting and cleaning of not-yet-sufficiently-size-reduced food that is then re-submitted to repeated mastication (rumination), leading to unprecedented chewing and digestive efficiency.
This article is part of the theme issue ‘Food processing and nutritional assimilation in animals’.
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