Which main characteristics could be used to separate shark 4 from 8?

Please provide me with more context! I need to know what "shark 4" and "shark 8" refer to in order to help you identify characteristics that could be used to separate them.

For example:

* Are you talking about specific shark species? If so, what are their scientific names?

* Are you referring to sharks in a particular location or habitat? This could help narrow down their characteristics.

* Are you talking about shark size or age? "Shark 4" and "shark 8" might be codes for individuals within a research study.

Once you provide more information, I can give you a more accurate and helpful answer.