Question: are crabs osmoconformers or osmoregulators?
Answer: Invertebrates. Most osmoconformers are marine invertebrates such as echinoderms (such as starfish), mussels, marine crabs, lobsters, jellyfish, ascidians (sea squirts - primitive chordates), and scallops. ... Mussels are a prime example of a euryhaline osmoconformer.