Are marine invertebrates endangered?

There are a few species of marine invertebrates that are endangered, but there are many that are not.  Some endangered species include many species of corals and the white abalone.  However, there are so many species of marine invertebrates that have not been well studied and little is known about them.  For example the giant squid lives at such a depth that we have not yet even seen a live specimen.  We do not know their numbers. In light of this fact, it is very hard to determine the true numbers of many marine invertebrates and thus, to determine whether they are endangered or not.