Hyperosmoregulation

Question 1

What are the 3 main challenges bony fish and lamprey face in freshwater

Answer 1

• diffusional salt loss across body surface
• osmotic water influx
• incidental water influx during feeding

Question 2

Where is most salt loss in bony fish and lamprey?

Answer 2

• gills, they’re designed for gas exchange

Question 3

What does osmotic water influx cause?

Answer 3

• swelling/water loading

Question 4

What are the 4 solutions to overcome freshwater challenges?

Answer 4

• do not drink
• highly impermeable skin
• produce copious dilute urine
• active ion uptake via gills

Question 5

What causes highly impermeable tegument?

Answer 5

• deep tight junctions minimize passive loss of ions

Question 6

What does the kidney act as in freshwater fish?

Answer 6

• bilge pump