California sea lion
More recently, studies on hydrodynamic detection in the California sea lion ("Zalophus californianus") have been done. Despite the structure of their mystacial vibrissae, different from those of seals, these sea lions can detect and follow a trail made by a small toy submarine. Sea lions use an undulatory pattern of tracking similar to that in seals, but do not perform as well with increased delay before they are allowed to swim and locate the trail.