A s the fog burned off on a recent April afternoon, Richard Hasegawa made his way along the southern edge of Golden Gate Park, passing the hustle and bustle of joggers and cyclists on MLK Drive before reaching a secluded spot near Mallard Lake. It took the biologist no more than five minutes of sifting through twigs and leaves at the water’s edge before he turned over a piece of wood and knew he had found what he was searching for.
There, wriggling in the sunshine, were two creatures that had never been documented on iNaturalist before: the Golden Gate leech, a predatory worm that only exists in the freshwaters of San Francisco’s largest park.
“I just felt this dopamine rush, this great feeling of ‘eureka!’” said Hasegawa, who lives in Berkeley and works for the environmental consulting firm WRA. “It filled me with a sense of wonderment, that there are things we walk past every day like this without realizing.”
But he couldn’t dwell on these feelings for long. Hasegawa had other work to get to: namely, “wrangling” the leeches for their close-up. Wielding a small digital camera in one hand and a twig in the other, he gently nudged the pea-sized animals into a jerry-rigged setup with an aquarium box. After providing them with a bit of moisture so they wouldn’t get dehydrated, he snapped away, capturing the distinctive black speckles on the underside of their abdomens and the dark ring on their posterior suckers. The muscular disc at the tail end of their bodies allows them to crawl, “advance on their prey and engulf it whole,” Hasegawa said. “Unfortunately, I didn’t get to witness that, but it’s incredible to see.”…