Aquatic Animals

Wetlands of the San Francisco Bay are important for many aquatic species. The calm water and protected salt marsh channels are an ideal nursery for many Pacific fish because the tides move nutrients in the form of phytoplankton and zooplankton throughout the Bay, while the structure and plant life of the channels provide shelter. The Hayward Shoreline salt marsh is a permanent home to many small crustaceans and fish and is visited by larger predators during high tides. 
Bat Ray
Bat Ray
Myliobatis californica
Bat rays live in shallow coastal and bay waters where they stay close to the bottom. Using their fins, they dig up clams, shrimp, fish, crabs, and other small animals for food. The wingspan of a bat ray can reach 6 feet, and they have a small veonmous spine at the base of their tails which they use for defense.
Eastern Mud Snail
Eastern Mud Snail
Ilyanassa obsoleta
An invasive species from the Atlantic coast of North America, it is likely that Eastern mud snails arrived here in shipments of oysters during the early 1900s. They roam the mudflats, eating detritus in the thin layer of film covering the mud. They share a similar niche to the native California horn snail, which has since been restricted to small salt pans where the Eastern mud snails can't survive.
Leopard Shark
Leopard Shark
Triakis semifasciata
Leopard sharks are found along the Pacific Coast, but prefer to spend time in shallow water near the bottom and can be seen in the marshes at high tide. They are born live at 8 to 9 inches long and can grow up to 6 feet long. Using their sensitive snouts, these non-threatening sharks forage for clams, worms, shrimp, crabs and fish on the ocean bottom.
Lined shore crab
Lined Shore Crab
Pachygrapsus crassipes
These crabs grow to 2.5 to 3 inches wide and inhabit rocky intertidal areas of the marsh. They eat algae, scavenge for dead animals and plants, and attack small invertebrates such as snails and isopods. Although lined shore crabs breathe with gills, they can retain moisture out of the water and breathe air for up to 70 hours in the shade.

Three-spined Stickleback
Three­-spined Stickleback
Gasterosteus aculeatus
These small fish grow to about 4 inches in length and are identifiable by the three dorsal fins on their backs, which resemble spines. They are found many places in the world in fresh or brackish water and eat small fish, crustaceans, and other small animals. When they breed, the males build a nest, dance to attract females, and guard the eggs until
they hatch.
yellow shore crab
Yellow Shore Crab (Mud Crab)
Hemigrapsus oregonensis
Also called a bay shore crab or mud flat crab, these crabs grow to 1.5 to 2 inches wide. They are commonly found on mudflats, where they eat green algae and scavenge for dead plants and animals. Because they can tolerate a wide range of temperatures and salinities, they are widespread in Bay Area wetlands. Female crabs can carry up to 4,500 eggs under their bellies, and after the eggs hatch the baby crabs float around in the water as microscopic plankton. Eventually they metamorphose into adults and sink to the bottom. As they grow, they shed their exoskeletons which can be found along the sides of the trail at the high tide line.

Contact Us

  1. Hayward Shoreline Interpretive Center
    4901 Breakwater Ave.
    Hayward, CA 94545
    (510) 670-7270


    Friday - Sunday
    10:00 AM - 5:00 PM

    Closed Nov. 11 & 25