Let’s Begin by Examining Respiratory Structures in Selected Aquatic Animals Focus on structure and function Focus on the diffusion rates and solubility characteristics of oxygen and carbon dioxide Focus on supplemental means for acquiring sufficient oxygen

Respiration in Unicellular and Small MultiCellular Organisms

Annelid Respiration

Bivalve Mollusc

Crab Gill = blood flow = water flow lamellae afferent vessel efferent vessel branchial chamber

Fish Gill

Concurrent Exchange Countercurrent Exchange

P O2 Length Countercurrent Exchange P O2 Length Concurrent Exchange

Ram ventilation - swimming with open mouth Obligatory - e.g. some sharks and tuna Facultative - e.g. mackerel - switch to ram ventilation at swimming speeds > ms -1

Terrestrial Respiratory Structures Lungs Mollusca Crustacea Amphibia Reptilia Aves Mammalia Tracheae Insecta (no circulatory fluid involved - tubules branch and deliver air directly to tissues)

Insect Respiration

Open Spiracle in Grasshopper Closed Spiracle in Grasshopper

Insect Tracheal System

Lungs diffusion lungs e.g. pulmonate snails ventilation lungs e.g. vertebrates positive press. lungs e.g. amphibians suction lungs (subatmospheric press.) e.g. mammals

Amphibian (Frog) Lung

Avian Lung

Respiratory Tract

Alveoli

pleural cavity lung diaphragm trachea bronchus Mammalian Lung

diaphragm exterior intercostals Inspiration == -- air

Expiration elastic recoil (surface tension) Internal intercostals air