Adaptations to different diets
- Created by: Emily Cartwright
- Created on: 26-05-14 10:17
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- Adaptations to different diets
- Differences in dentition
- Herbivores
- Tough plant material must thoroughly ground up food before it is swallowed
- Grazers (e.g. cows and sheep) have small, flat top incisors on lower jaw only and cuts against a horny pad on upper jaw
- The canine teeth are not present or indistinguishable from the incisors
- The diastema (a gap) between front teeth and premolars. Allows tongue to move freshly-cut grass to the large grinding surfaces of the molars
- The horizontal jaw movement is a circular grinding motion
- Molars interlock in a W M arrangement
- Teeth continuously growing due to open, unrestricted roots
- Carnivores
- Teeth for catching/killing prey, cutting or crushing bones and for tearing meat
- The sharp incisors grip and tear flesh from the bone
- Large canine teeth curved and pointed for seizing/killing prey and tearing flesh
- Powerful , well developed jaw muscles to enable gripping prey finmly and help in crushing bone
- The vertical jaw movement allowing the jaw to open widely for capturing and killing prey
- Carnassials (specialised cheek teeth), with cisor -like shearing action for cutting flesh
- The premolars and molars are for cutting an crushing
- In total, adult humans have 32 teeth
- 8 incisors for biting and cutting
- 4 canines for biting and cutting
- 10 premolars and molars for chewing, crushing and grinding
- Our teeth are not particularly specialised as we are omnivores - we eat both plant and animal material
- 10 premolars and molars for chewing, crushing and grinding
- 4 canines for biting and cutting
- 8 incisors for biting and cutting
- Herbivores
- Herbivore Digestion
- Herbivorous mammals have a diet that consists of cellulose
- But mammals don't produce the enzyme cellulase to break down cellulose
- Instead, these animals have evolved a symbiotic relationship with bacteria which do produce cellulose; this relationship is called mutualism
- But mammals don't produce the enzyme cellulase to break down cellulose
- Mutualism: 'A close association between organisms of two different species, where both organisms benefit from the relationship'
- Herbivores can be divided into ruminants and non-ruminants
- Ruminants (Fore-gut digesters)
- A ruminant is an animal with a specialised stomach (rumen) in which mutualistic bacteria live
- Ruminants have a stomach made up of 4 chambers
- Three of these chambers are formed by the oesophagus and one is the true stomach
- The region of the gut occupied by the bacteria is kept seperate from the main digestive region so that;
- Food can be kept there long enough for bacteria to digest the cellulose
- The bacteria are isolated from the cow's own digestive juices so that they are in the optimum pH for their activities and they are not killed by extremes of pH
- The region of the gut occupied by the bacteria is kept seperate from the main digestive region so that;
- Three of these chambers are formed by the oesophagus and one is the true stomach
- 1. Mouth
- Grass chopped by teeth, mixed with saliva to form cud and then swallowed
- 2. Rumen
- Cud is mixed with cellulose digesting bacteria to produce glucose
- This is fermented to form organic acids that are absorbed into the blood to provide energy for the cow
- Waste products - carbon dioxide and methane - are passed out
- This is fermented to form organic acids that are absorbed into the blood to provide energy for the cow
- Cud is mixed with cellulose digesting bacteria to produce glucose
- 3. Reticulum
- The cud arrives here before being regurgitated into the mouth and chewed again
- 4. Omasum
- The cud passes here to reabsorb water
- 5. Abomasum
- This functions like a 'normal' stomach and protein is digested
- 6. Small intestine
- Protein and lipid digestion followed by absorption
- Non ruminants (Hind-gut digesters)
- In non ruminant herbivores e.g. rabbits, the caecum is enlarged to provide a region for mutualistic micro-organisms to break down cellulose
- As the digestion of cellulose to glucose occurs after the ileum, the glucose can't be absorbed
- Hind gut digesters get round this by re-eating the faeces and absorbing the glucose 'second time around'
- As the digestion of cellulose to glucose occurs after the ileum, the glucose can't be absorbed
- In non ruminant herbivores e.g. rabbits, the caecum is enlarged to provide a region for mutualistic micro-organisms to break down cellulose
- Ruminant v Non ruminant
- Ruminants are more efficient than non ruminants as the rumen contains a greater variety of mutualistic bacteria than the caecum
- Ruminants are therefore able to achieve a more complete breakdown of cellulose and consequently absorb more glucose
- Carnivores have a short gut because protein is easy to digest. Herbivores have a long gut because cellulose is difficult to digest
- Ruminants are more efficient than non ruminants as the rumen contains a greater variety of mutualistic bacteria than the caecum
- Ruminants (Fore-gut digesters)
- Herbivorous mammals have a diet that consists of cellulose
- Differences in dentition
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