Biology 2.4 - Comparing Herbivores with carnivores

What type of diet do herbivores have?

High cellulose diet

What type of diet do carnivores have?

A diet high in proteins and lipids;also a high energy diet

In the herbivore gut, what type of gut do ruminants have?

They have a highly specialised gut

In the herbivore gut, what type of gut do non-ruminants have?

A very long gut to allow cellulose digestion

In the herbivore gut, what do non-ruminants also have?

A large caecum containing cellulase-producing bacteria

How long is the carnivore gut?

Relatively short gut

What does the carnivore gut have?

A large stomach for digesting a protein-rich diet

In the carnivore gut, how big is the caecum?

Very small (and vestigial)

What type of teeth do herbivores have?

They have large, flat and open rooted teeth for grinding the tough cellulose cell walls of plant tissue

What do many herbivores have that allow them to digest and break down plant foods?

They have several pairs of broad molars that they use to grind leaves, shoots and twigs

What consists in herbivore dentition?

• Molars and premolars

• Jaws

• Incisors

• Dental pad

• Diastema

In herbivores, what shape do molars and premolars fit together in?

A 'W M' shape

In herbivores, what feature do the jaws have?

Loos articulation and are capable of moving sideways which allows these interlocking teeth to grind food effectively - producing a circular grinding action

In herbivores, what are most herbivores missing?

Missing canines entirely or they are indistinguishable

Why do some herbivores have large incisors?

For clipping or tearing vegetation but they may only occur on the lower jaw. Vegetation is cut against a dental pad on the upper jaw

In herbivores, what is the diastema?

A space where the tongue can push food towards the grinding cheek teeth

What consists in carnivore dentition?

• Canines

• Molars and premolars

• Strong jaw muscles

• Carnassial teeth

In carnivores, what are the features of canines?

They are long and pointed which enables the carnivore to pierce flesh and to seize and kill prey

In carnivores, what do the molars and premolars have?

They have sharp cusps that cut and crush

Why do carnivores have strong jaw muscles?

Jaws move in a vertical plane and can open wide and clamp down strongly to hold prey down

In carnivores, what do the carnassial teeth act as?

They act as shears - they slide past each other ripping muscle from the bone

What do ruminants provide?

20% of all animal protein that is eaten by humans

Give some examples of some ruminants

Cows and sheep

What is mainly the diet of ruminants?

Mainly cellulose wall material

Because animals do not make cellulase, what does this mean for them?

They do not digest beta glycosidic bonds in cellulose

What do ruminants rely on?

Microbes in their gut - a mutualistic relationship, the microbes secrete cellulase

In non-ruminants, where are the bacteria found

In the caecum and appendix e.g in rabbits

In ruminants, where is the bacteria found?

In the rumen

What are the 4 chambers of the ruminant stomach?

1. Rumen

2. Reticulum

3. Omasum

4. Abomasum

In digestion of the ruminant, what happens to the teeth that cut the grass?

It is mixed with saliva and a cud is formed, it is then swallowed into the rumen

In digestion of the ruminant, what is the food in the rumen mixed with?

Anaerobic microbes (bacteria, fungi and protoctista) that secrete cellulases, digesting the cellulose into glucose

In digestion of the ruminant, what happens to the glucose?

It is then fermented into organic acid which is absorbed into the bloodstream as an energy source - by products, methane and carbon dioxide are released

In digestion of the ruminant, what does the rumen act as?

As a fermentation vat - a cow's rumen has a capacity of up to 95 litres

In digestion of the ruminant, where is the fermented grass passed to?

The reticulum where it is reformed into cud, regurgitated and chewed again - this is repeated several times

In digestion of the ruminant, what does the cud have added to it?

Urea from the saliva - this provides the anaerobic bacteria in the rumen with a nitrogen source thus enabling them to synthesise amino acids and proteins

In digestion of the ruminant, where does the cud then pass to?

The omasum where water and organic acid (from the fermented glucose) are absorbed into the bloodstream

In digestion of the ruminant, what is the abomasum?

The true stomach where protein is digested at pH 2

In digestion of the ruminant, where is the food then passed to?

The small intestine where products are absorbed