Question

Which of the following are osmoconformers?
1. Sharks
2. Rays
3. Hagfish
4. All of the above

Answer 1

Hint: Osmoconformers are the organisms (marine invertebrates) which keep their internal solutes isotonic to their external environment. It also suggests that the osmotic pressure inside the cell of an organism is about equal to the osmotic pressure of its external or surrounding environment.

Complete Answer-
To solve this question, now, we have to look towards the options we are provided with.
Firstly, sharks are the marine organisms and most of the osmoconformers belong to these marine invertebrates. Sharks actively regulate their internal salinity and match it with their outside environment.
The blood composition of these cartilaginous fishes is similar to that with bony fishes. Rays are osmoconformers whose body fluid concentrations are isotonic with seawater.
We generally know about the invertebrate osmoconformers by Hagfish are the one and only. Vertebrates come under these marine organisms (osmoconformers). These are the only species which are documented to absorb amino acids directly across the skin.
So, above three options are correct and mentioned marine animals are osmoconformers. To show the correctness of all three options we use all of the above.

So, the correct option is Option (D) All of the above.

NOTE-
An advantage of osmoconformers is that such organisms don’t need to expend as much energy in respect to other organisms like osmoregulators. More examples are starfish, lobsters, jellyfish, and mussels. Mussels have special quality to survive in a broad range of external salinities. In order to balance their internal salinity sharks are also able to absorb sea water directly.
It is due to the high concentration of urea which is kept inside their body.