Some can fit in the palm of your hand, while full grown they can weigh over 200 pounds. At any size, it’s hard not to be amazed by the California Bat Ray. Perhaps one of the Bay’s most bizarre creatures, these underwater bird-like fish are but one in the large class of cartilaginous fish. We are lucky to see them frequently in San Francisco Bay, especially around our home port of Redwood City.
Their silky skin and ‘wings’ (which are really pectoral fins) can easily make you forget they possess a formidable defense: a harpoon-like barb filled with a neuro-toxin! Still, with a careful instructor they are perfectly safe to touch, and always a highlight when we see them aboard the Robert G. Brownlee. Their teeth are fused into upper and lower plates, which simply crush their prey. Bottom feeders, like their entire family, they are very well suited to the sandy, muddy bottoms of estuaries such as the San FranciscoBay. Their food source is plentiful too: molluscs, shrimp, and small fish. Thus, while many fish species in the bay have indicated sharp reductions in populations over the last 40 years of our Fish Data surveys, the Bat Ray is doing relatively well. In fact, we have witnessed strong growth in their populations from the 1970s to the present.