Is a rat a Carnirvore

Carnivores (carnivores)

Carnivores are animals that feed mainly or exclusively on animal tissue and derive their nutrients from it. Carnivores include species of almost all animal phyla. Carnivores should not be confused with the order carnivores (Carnivora). Predators (Carnivora) are not necessarily carnivores (Carnivora) and carnivores (Carnivora) are not necessarily predators (Carnivora). There are both carnivores that do not belong to the order of predators, as well as predators that, like many bears, mainly feed on vegetable food and thus belong to the omnivores.

A distinction is made between strict canivores such as felids, which feed almost exclusively on meat, and facultative carnivores, which sometimes also use other food sources. Facultative carnivores differ from omnivores (omnivores) in that their main food source is animal tissue (Kleffner 2008).

Differentiation of carnivores depending on their main prey according to Kleffner (2008):

  • Insectivore: insectivore
  • Molluscivors; also as a subgroup of the insectivore: mollusc-eaters or shellfish-eaters
  • Piscivore: fish eater
  • Sanguinivore: Licking blood

Differentiation of carnivores depending on their size and the proportion of vertebrates according to Kleffner (2008):

  • Meat group: over 70% vertebrate meat
  • Meat bone group: over 70% vertebrate meat and large bones
  • Meat nonvertebrate group: 50 - 70% meat and / or fruits and insects
  • Nonvertebrate meat group: fruits and / or insects and less than 50% vertebrate meat

Carnivores have enamel cusps with several complexly arranged tips (sekodont), which are particularly suitable for cutting and chopping. Most carnivores have brachydontic teeth with low crowns and well-developed or closed roots and complete growth (Fritz 2007).

The incisors and canini are well developed in almost all canivores, the fangs (upper jaw: premolar 4, lower jaw: molar 1) are particularly pronounced. In many insectivores the number and / or size of the teeth are reduced, but the tongue is particularly long (Kleffner 2008).

Author: 20100; Creative Commons license; Original file (as of 05.2013)Author: 20100; Creative Commons license; Original file (as of 05.2013)
Figure 3: Skull of a marten. The marten tears, chops and crushes its food. He's got carnivorous teeth. The chewing surface of bunodont molars is reduced compared to omnivorous ones like the bear (Dierks 2001).
Figure 4: Skull of a cat. The cat's teeth are short and stocky. It is an extremely secodontal carnivore dentition (Nickel et al. 2004).

The digestive tract is comparatively short in relation to the length of the body. The ratio of intestinal length to body length in carnivores is about 4: 1 (Wagner 1835). The stomach is simply built but comparatively large and elastic. The stomach and small intestine are not chambered and the appendix is ​​small, sometimes completely absent. The gastrointestinal passage is short and the food is very easy to digest (Kleffner 2008).

The basal metabolic rate is higher in carnivores than in herbivores (herbivores) (Kleffner 2008).

Omnivores (omnivores)

Animals whose diet is composed of plants and animals are referred to as omnivores, omnivores or pantophages. The term does not include a taxonomic group but describes various species that are not closely related to one another. Typical representatives are, for example, brown rats and wild boars.

The name Omnivor is characterized by a variety of different diets. In addition to the generalized omnivores, the group also includes granivorous, frugivorous and nectarivorous species, as well as mixed forms from these subgroups. Real omnivores can make good use of all food components (Kleffner 2008).

When examining the stomach contents of rats, both vegetable and animal components were found in 11% of the cases. In 10% of the cases only meat or fish (Niethammer & Krapp 1978). In wild boars, animal components were found in 47% of the stomachs, with about 0.9% of the total amount in the stomach being of animal origin (Fielitz 2003). According to studies by Briedermann (1976), animal nutrition in wild boars accounts for around 4%.

Hoffmann (1999) observed animal components as primary food in the omnivorous European badger. However, badgers used very different food sources. Especially in the summer and autumn months, vegetable components play a greater role in the badger's diet.

Table 1: Comparison of the stomach contents in herbivores and omnivores using the example of red deer and wild boar. In the list presented, deviations between individual animals and seasonal feed intake are not taken into account. These are average values ​​(according to Fielitz 2003).

Red deerwild boar
  • Grasses (29 species): 60.2%
  • Herbs (12 types): 24.7%
  • Ferns (2 types): 4.7%
  • Fruits (3 types): 2.9%
  • Needles (2 types): 1.6%
  • Bark: 0.8%
  • Mushrooms (4 types): 0.5%
  • Other: 4.3%
  • Lichen: 0.3%
  • Humus: 0.1%
  • Grasses: 20.2%
  • Fruits: 17.3%
  • Herbs / shrubs / trees: 13.4%
  • Roots: 12.2%
  • Humus: 11%
  • Mushrooms: 7.6%
  • Animal components: 0.9%
  • Other: 17.4%
Figure 5: Comparison of the food choices of herbivores (red deer) and omnivores (wild boar) according to Fielitz (2003). The proportion of a certain type of food does not have to make up a large proportion in its entirety.

A species can have a broad food spectrum and thus be considered a generalist, while the individual populations or even individuals can often have a relatively narrow food spectrum and thus tend to specialize (Nentwig et al. 2012). Steiniger (1950) observed brown rats on Norderoog in the Wadden Sea, off the west coast of Schleswig-Holstein, which mainly lived by catching birds.

Omnivores that have a wide range of foods with foods of different consistencies have bunodontic teeth with rounded, wart-shaped cusps. Most omnivores have brachydontic teeth with low crowns and well-developed or closed roots and complete growth (Fritz 2007). However, an adaptation in the dentition can look very different depending on the type (Kleffner 2008).

Author: NCSSM; Creative Commons license; Original file (as of 05.2013)
Figure 6: Skull of a pig. The pigs' teeth are very original and typical omnivorous teeth (Richter 2011).Figure 7: Skull of a rat. The omnivorous rat's dentition is geared towards a more graminivorous (grass-eating) diet.

The ratio of intestinal length to body length in omnivores such as humans is about 6: 1 (Wagner 1835). In pigs, the length of the intestine is around 15 times the length of the body (Callies 2012). The ratio for badgers is 8: 1 (Hoffmann 1999). The complexity of the digestive tract lies between that of carnivores and that of herbivores. Most omivores have a simple stomach that is smaller than that of carnivores. The small intestine is rather short and the large intestine moderately developed. The larger the proportion of plant-based food, the more developed the large intestine is. Depending on the type, this can serve as a fermentation chamber (Kleffner 2008).

The basal metabolism lies between carnivorous and herbivorous animals (Kleffner 2008).


Herbivores are primary consumers. They are the first level of consumers in an ecosystem. Herbivores include all animals that feed on the leaf organs of plants (grass, leaves, herbs) (Fritz 2007). Depending on the definition, this also includes species that in some cases also feed on fungi, protists or bacteria.

About 90% of the entire mammal population are herbivores (Fritz 2007).

Cellulose cannot be broken down by the body's own enzymes, which is why mammalian plants can only be digested to a limited extent. Herbivores use symbiotic microorganisms to break down the cellulose fibers. The utilization of cellulose by the microorganisms produces short-chain fatty acids, which can be used by the host animal as an energy source. In addition, CO is generated2 and methane which are lost as energy. In addition, the microorganisms are an important source of protein for coprophages and forestomach fermenters and provide B vitamins (Fritz 2007).

In order to ensure the most effective digestion of the plant particles, a thorough mixing of the food pulp and a sufficiently long residence time of the food in the digestive tract is required, as this is a time-dependent process (Fritz 2007).

The ratio of intestinal length to body length is around 28: 1 in herbivores such as sheep and 10: 1 in horses (Wagner 1835).

Herbivores use different digestive strategies to digest food particles.

A distinction is made according to Fritz (2007):

  • Foregut fermenters, which include ruminants, colobus monkeys and kangaroos, have very spacious, compartmentalized stomachs for this purpose.
  • Large intestine fermenters such as equidae and rodents have either a large, partially chambered appendix and / or a large colon.
    • Colon fermenter: animals over 50 kg
    • Caecum fermenter: Less than 5 kg
Figure 8: digestive tract (after Townsend et al. 2009). The digestive tract of herbivores can look different. It has fermentation chambers that contain a rich community of microorganisms.

a) Rabbits, with a fermentation chamber in the enlarged appendix, appendix fermenter

b) Zebra, with fermentation chambers in the appendix and rectum, colon fermenter

c) Sheep, with fermentation in the forestomach - an enlarged part of the stomach - as well as in the rumen (rumen) and reticulum (net stomach), forestomach fermenter

d) Kangaroo, with extensive fermentation chamber in the proximal area of ​​the stomach, forestomach fermenter

In forestomach fermenters, the processes are very slow. But they are effective because the digestive products can be absorbed straight away in the small intestine. With colon fermentation, quality is replaced by quantity. Due to the shorter storage time in the stomach, they take in more food and process it faster (Fritz 2007).

In the case of small herbivores, the energy yield from microbial fermentation is insufficient to meet the needs. They gain most of their energy from the absorption of the cellular substances in the small intestine. Foregut fermentation is possible as a digestive strategy from a body weight of 4 kg. Small ruminants such as muntjacs eat particularly easily digestible food (Fritz 2007).

Small colon fermenters usually have a large appendix that allows them to hold back food for longer. There are different strategies. Animals such as rabbits and koalas periodically direct the contents of the cecum into the proximal colon. There, liquid and finer particles are retained in the so-called haustra. The particles are transported back into the caecum by means of anti-peristaltic waves. Guinea pigs and chinchillas use a longitudinal furrow in the proximal colon and caecum formed by folds of the mucous membrane as a separation mechanism. Bacteria and mucus are channeled into the furrow and transported back into the appendix by means of antiperistaltic bowel movements (Fritz 2007).

According to Fritz (2007), herbivores can be divided into three food groups: grasses, deciduous and intermediate types. Grasses feed on grasses that contain silicate and often have a high fiber content. They can make better use of fibers than leaf grass. Deciduous trees feed primarily on dicotyledonous plants such as leaves and twigs as well as the bark of shrubs, bushes and trees.

The teeth of the herbivorous mammals are characterized by wide incisors with which they cut off the plants. The canines are reduced or completely absent. They have molarized premolars and molars that they use to grind food. To grind the food, transverse chewing movements are possible and necessary. There are also toothless sections and often a frontally elongated skull.

According to Fritz (2007), a distinction is made between the following tooth types based on the structure of the enamel:

  • selenodont: crescent-shaped enamel protuberances; ruminant
  • lophodont: comb-like structured chewing surface with ridges running parallel to the transverse or longitudinal side of the tooth; For example solipeds and many rodents
  • loxodont: comb-like structured chewing surface with sloping ridges. The teeth look like a washboard; For example, some types of mice
  • bilophodont: surface with two transverse furrows / ridges; Vervet monkeys and kangaroos

In many herbivores, the teeth grow back continuously, sometimes even for life. In addition, many herbivores have developed high-crowned (hypsodontic) teeth with relatively short or open roots. The degree of hypsodontia depends on the diet. Grass cutters usually have higher-crowned molars than leaf cutters, as grasses have a higher content of silicates, which, together with dust contamination on the food, increase wear (Fritz 2007).


Briedermann L. (1976): Results of a content analysis of 665 wild boar stomachs. Zool.Garden. 46 (3): 157-185

Callies A. U. (2012): Investigations on the amount of intestinal mucus and its mannose content as well as on the in vitro adhesion of Salmonella Typhimurium to the mucosa of the ileum and cecum of young pigs under the influence of the feed structure, Hanover, dissertation

Dierks K. (2001): Investigations on the skull of the stone marten (Martes foina Erxleben 777) Skull measurements and dentition disorders, dissertation, Justus Liebig University Giessen

Hofmann T. (1999): Studies on the ecology of the European badger (Meles meles, L. 1758) in the Hakelwald (north-eastern Harz foreland), dissertation

Fielitz U. (2003): Investigations into the behavior of radiocesium in wild boars and other biomedia of the forest

Fritz, J. (2007): Allometry of the droppings particle size of herbivorous mammals, reptiles and birds. Dissertation, LMU Munich, pp.66-103

Kleffner H. (2008): Literature study on the digestibility of energy and nutrients in wild carnivorous and omnivorous mammals as a basis for energy value estimates in feed, dissertation, Munich

Nentwig W., Bacher S., Brandl R. (2012): Interactions between different species, Ecology compact, Bachelor 2012, pp 97-172

Nickel R., Schummer A., ​​Seiferle E. (2004): Textbook of the anatomy of domestic animals, Volume II: Guts, Parey bei Mvs; Edition: 9th, unchanged. A. (March 10, 2004)

Niethammer J., Krapp F .: Handbook of Mammals in Europe. Volume 1, Rodentia I. Akademische Verlagsgesellschaft, Wiesbaden 1978: p. 401

Townsend C. R., Begon M., Harper J. L., Hoffmeister T.S., Steidle J. L. M., Thomas F. (2009): Ecology; Springer textbook, ISBN: 978-3-540-95896-3

Richter H. (2011): Comparative analysis of fluoride-induced changes in the dentin of permanent molars of cloven-hoofed animals (Artiodactyla; Cervidae and Suidae), dissertation, University of Hildesheim

Steiniger F. (1950): Brown rats in the wild

Wagner R. (1835): Textbook of comparative anatomy