Animal Nutrition III (Ch. 41)

Keywords• Ruminant digestion• Symbiosis

– Definition

– Algal-invertebrate

– Chemoautotroph-invertebrate

• Hydrothermal vent

• H2S (sulfide)

• chemoautotrophy

mouth

Mechanicaldigestion storage

absorption

anus

Basic parts of alimentary canal

Structure of cellulose

Cecum

• Allows breakdown of cellulose in herbivores

• One opening and exit - lower oxygen, slower passage

• Digested cellulose must be reintroduced to digestive system

Ruminant digestion

Ruminant 4 chambered stomach

• Rumen and reticulum - where symbiotic bacteria and protists break down cellulose

• Cow rechews food

• Omasum - where water is absorbed

• Abomasum - further digestion by cow’s enzymes

Symbiosis

Autotroph-invertebrate symbiosis

• Symbionts are algae

• Algae photosynthesize and provide molecules such as sugars to the host

• Hydra, anemones, giant clams, corals

Examples

Chemoautotroph-invertebrate symbiosis

• Symbionts are chemoautotrophic bacteria

• Bacteria use hydrogen sulfide as an energy source and provide molecules such as sugars to host

• Tubeworms, clams, mussels

Where do we find these organisms?

Life at a vent

H2SO2

Respiratory surface of tubeworm

Hb

H2S

O2

Oxygen and sulfide are transported to the bacteria

Chemoautotrophy: Bacteria oxidize sulfide and use the energy for carbon fixation

H2S + O2 SO4=

ADP ATP

CO2

carbohydrate

Calvin-BensonCycle