Living in Water challenges Obtaining Oxygen www arkive

Living in Water: challenges?

Obtaining Oxygen www. arkive. org

Obtaining Oxygen in Water Flow

Countercurrent Exchange

Lungs

Buoyancy: Bony Fishes • Neutrally buoyant • How do fish move up and down? What would happen if fish didn’t adjust the amount of gas in the bladder when moving up?

Buoyancy: Bony Fishes • 2 types of bladders

Buoyancy Other Buoyancy Mechanisms • Cartilaginous Fishes – High oil content in liver – Nitrogen-containing compounds

Mechanoreception • Gravity detector • Lateral line system

Electroreception https: //www. youtube. co m/watch? v=JDPFR 6 n 8 t. AQ

Internal Environment of Fishes • Water and ion gradients move. What direction? • Osmotic balance • Freshwater − Water moves? − Ions move? • Saltwater − Water moves? − Ions move?

Internal Environment of Fishes

Exchange of Water and Ions Freshwater Fish • Skin impermeability • Gills – not so much • Influx of water – How to compensate? • Out flux of ions – How to compensate?

Exchange of Water and Ions Marine Teleosts • Impermeable integument • Gills – not so much • Cartilaginous fish – Retain urea – How to deal with salt • Bony fish – Loosing water – How to cope?

Moving in Water • Swim with anterior to posterior sequential contractions of muscle segments…