2. Giving specifically-named examples of each, compare osmoconformers and osmoregulators. Explain why certain animals fall into one or the other category

- Osmoconformers: echinoderms, lobsters, jellyfish, ascidians, mussels, etc.

- Osmoregulators: freshwater fish

Explanation:

Osmoregulation refers to the control of the osmotic pressure in order to maintain the organism's homeostasis. Osmoconformers are animals that maintain an internal osmotic pressure in equilibrium with the surrounding water environment, i.e., they are isoosmotic, where salinity within their cells is the same as the external (aqueous) environment. These animals (e.g., marine invertebrates) continuously need to regulate the cellular osmotic pressure, which is accomplished by decreasing the intracellular concentration of osmotically active solutes of their tissues. Conversely, osmoregulators are animals that have to control their internal osmolarity despite the salt concentrations in the environment. Osmoregulatory freshwater fish are hypertonic, where the concentration of salt is higher in the body compared to the surrounding environment. These animals absorb controlled amounts of water through the mouth and accumulate salt from the external medium through mitochondria-rich cells in the gills.