The short answer is "no" unless you have done prior reading/research on the animals you're wanting. Check the local laws first if you haven't already, as there may be license requirements and/or collecting limits. Back when I was in TX the regulations seemed pretty fuzzy about non-edible inverts and there were a number of protected animals. Many coastal animals are also completely unsuitable for the average nano. If all is well in the legal department, make sure you know how to correctly identify and care for the animals you're interested in so that you can both meet their environmental needs and ensure that your nano doesn't become lunch. If you put something in your tank and it doesn't work out, you can't simply take it back to the beach. You should also plan on QTing.