Elizabeth Hilmoe
BSCI 207 HW 8: Nutrients, osmoregulation and thermoregulation
1. Letโs think about how different animals adapt and adjust to control their osmolarity. Consider ONE
of the following: a tunafish (marine), a goldfish (freshwater) or a dog. For the listed items, note
relative concentrations or how water and salt move. Mark with a * movement that requires energy
input needed to move salts against their concentration gradient. It is OK if you are a bit redundant
between different entries. Try to note everything that is happening.
Animal= Goldfish (freshwater)
Osmolarity relative to environment= there is higher osmolarity relative to the environment- also
known as hyperosmotic
Ingestion= ingests water through food and by osmosis
Salt and water
Passive transport= water enters by osmosis, and salts diffuse out
Water osmosis= water enters the body through skin and gills
Salt diffusion= salts diffuse out through the gills
Gills or lungs= gills
Water= water enters through the gills
Salt= active salt uptake * to counteract loss
Kidneys
Water= produces large amounts of dilute urine to remove the excess water
Salt= reabsorbs salt * to maintain the internal concentrations
Urine concentration= very dilute because it lives in a water concentrated environment so itโs trying
to expel as much water while preserving the salt inside its body
Urine amount= large volume to remove the excess water
2. Countercurrent exchange is something that organisms take advantage of for a number of systems.
Come up with an example for one of the following systems: circulation, osmoregulation or
thermoregulation. For your example, list what is being transferred, what two fluids are moving in
countercurrent directions, and what is the advantage of setting things up this way.
System
Thermoregulation
Example
Marine mammal
flippers (Like the seal
we talked about in
class)
What is being
transferred?
Heat!!!
