Invertebrates are important food sources for the scores of shorebirds that use Nehalem Bay. The following invertebrates can be found in estuary mudflats (Emmett et al. 1991):
- Bay Shrimp (Crangon franciscorum)
- Blue mussel (Mytilis edulis)
- Pacific littleneck clam (Protothaca staminea)
- Dungeness crab (Cancer magister)
The bay shrimp is the dominant decapod in most Pacific Coast estuaries. It is an important prey item for many Pacific Coast fish and crab species. Estuaries are used as nursery areas by this species, with lower salinity areas being particularly important to young shrimp (Monaco et al. 1990)
The Dungeness crab is important as both a predator and a prey species in estuarine habitats.