Invertebrates in the Sanctuary

There are over 330 known invertebrates in Greater Farallones National Marine Sanctuary including mollusks, echinoderms, cnidarians, arthropods, poriferans, and polychaetes. Learn about these groups below.

Learn more about Sanctuary wildlife.


Mollusks are a type of invertebrate species. It is a broad branch name for soft-bodied creatures, many of whom have shells! Some of the most common mollusks in Greater Farallones National Marine Sanctuary include snails, nudibranchs, squid, and octopus.

Photo: Opalescent Aeolid nudibranch (Hermissenda opalescens); Credit: Steve Lonhart, NOAA


Echinoderms are one of the most diverse groups of marine invertebrates. They play important ecological roles as both predator and prey in their environment ranging from the intertidal and sandy beaches to the deep seafloor. Examples of echinoderms in the Sanctuary include sea stars, sea urchins, sea cucumbers, and sand dollars.

Photo: Bat star (Patiria miniata) and Purple urchins (Strongylocentrotus purpuratus); Credit: Claire Fackler, NOAA


Cnidarians are characterized by radial symmetry, thin tissues, and stinging tentacles. There are over 10,000 species of cnidarians in the ocean. Examples of cnidarian species in the Sanctuary include jellyfish, anemones, and deep sea coral.

Photo: Aggregating anemone (Anthopleura elegantissima) and Giant green anemone (Anthopleura xanthogrammica); Credit: Dr. John Pearse, UC Santa Cruz

Striped shore crab-Photo Credit Chad King NOAA


Arthropods are characterized by an exoskeleton, meaning their skeletal system is on the outside of their body. Many species of arthropods can be found in both marine and terrestrial environments. In the ocean, arthropods live in nearly every corner of the world and in every marine habitat including on the shore, seafloor, open ocean, and deep sea. Examples of arthropods in the Sanctuary include crabs, shrimp, krill, and copepods.

Photo: Striped shore crab (Pachygrapsus crassipes); Credit: Chad King, NOAA MBNMS


Poriferans are marine sponges. They are simple marine organisms with dense, porous skeletons that live attached to the seafloor in various habitats including hard, rocky surfaces, sandy, and muddy bottoms. Sponges are very diverse and found in every ocean on Earth. Many different species can be found in the deep ocean in Greater Farallones National Marine Sanctuary.

Photo: Boring sponge (Cliona celata) and Cobalt sponge (Acanthancora cyanocrypta); Credit: Steve Lonhart / NOAA MBNMS


Polychaetes are a type of marine worm. They are usually around 4 inches long and have a vast range of colors. They have pairs of parapodium, which act as paddles for movement. Many diverse species of polychaete can be found in Greater Farallones National Marine Sanctuary.

Photo: Feather duster worm (Eudistylia polymorpha); Credit: Chad King, NOAA MBNMS