I find different reports saying there are 32, 35 or 37 animal phyla. I also wonder which of those phyla contain exclusively marine invertebrates and those contain marine and not marine invertebrates.
Phylum is an arbitrary category and different researchers have different opinions. I recommend to have a look at Edgecombe et al. (2011) Higher-level metazoan relationships: recent progress and remaining questions. Org Divers Evol (2011) 11:151–172. They operate with 36 major taxa. Most of those 36 taxa includes marine representatives except Onychophora and Micrognathozoa.