Looks wise, the dabs is Picasso-like in its asymmetry. With a compressed body, it lies flat on the sand where the head region displays not one but two visible eyes. However, just below the close-set orbs only half the mouth can be seen. These caddywampus characteristics render a sanddab indescribable in terms of using face up or face down. Instead, eyed side or blind side is preferred. The body’s eyed side matches the color and pattern of the surrounding sand substrate and is further encrypted by black speckles. The blind underside is whitish. Though freaky-looking, a sanddab is an excellent hunter, able to dart lightening-fast to nab prey on the sand’s surface or to swim in a graceful, undulating manner while capturing food midwater.
Small size and specialized spawning behavior may explain much of the speckeled sanddab’s abundance. Growing no more than a few inches long assures no pressure from commerical and recreational fishers. As to spawning, females keep all their eggs in one basket, so to speak, because they simultaneously incubate three groups of eggs, each at a different developmental stage. In this way, a female spawns multiple times per season, thereby increasing survival of at least some of the collective brood. Once hatched, sanddab larvae join the floating plankon party where they feed on tiny shrimplike crustaeans called copepods. How long the larvae spend in this realm depends on the speed of their development, which hinges on how much food is within their reach.
If a sanddab larva makes it to fish form without first becoming prey, it sinks to the bottom to, hopefully, live out its lifespan of about three years. Adults eat widely, from juvenile fish to various invertebrates, benefited by long jaws and sharp teeth. Though poor diggers themselves, sanddabs take advantage of digging experts — bat rays and stingrays. The rays forage for food by digging craters in the sand. Once departed, sanddabs move into the depression to scarf leftovers. Recently, I came upon a bat ray cratering the sand. After the ray left and the dust settled (literally), a frenzy of sanddabs scurried into the excavation, One triumphed with a polychaete worm in its jaws.
If a sanddab survives to adulthood, its life may still be curtailed by predators like larger fish, cormorant birds and marine mammals. Low visibility may also be a life-limiting factor because these little flatfish rely on sight to capture food. Interestingly then, poor visibility (a frequent diver complaint) adds a little-considered twist to the list of risks that may compromise a speckeled sanddab’s existence.
— Judith Lea Garfield, naturalist and underwater photographer, has authored two natural history books about the underwater park off La Jolla Cove and La Jolla Shores. Send comments to firstname.lastname@example.org.