Animal Nutrition III (Ch. 41)

Keywords Ruminant digestion Symbiosis –Definition –Algal-invertebrate –Chemoautotroph- invertebrate Hydrothermal vent H 2 S (sulfide) chemoautotrophy

mouth Mechanical digestion 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 H2SH2S O2O2

Respiratory surface of tubeworm Hb H2SH2S O2O2

Oxygen and sulfide are transported to the bacteria

Chemoautotrophy: Bacteria oxidize sulfide and use the energy for carbon fixation H2SH2S+ O 2 SO 4 = ADP ATP CO 2 carbohydrate Calvin-Benson Cycle