Kenneth Glad
In a quiet patch beside the water, a small animal turned up where few people would think to look.
Near Mallard Lake in Golden Gate Park, Richard Hasegawa lifted a piece of wood and found two tiny leeches moving underneath.
The sighting happened during this year’s City Nature Challenge, when residents across the Bay Area photographed plants and animals for iNaturalist.
According to SFGATE, Hasegawa, a Berkeley-based environmental consultant and amateur naturalist, recorded the Golden Gate leech, a small freshwater predator linked to San Francisco ponds.
Two leeches under a piece of wood
Before going out, Hasegawa had searched for unusual local animals that might be missed during the challenge. SFGATE writes that he found earlier research on the Golden Gate leech, first described in 1987 by German evolutionary biologist Dr. Ulrich Kutschera.
At Mallard Lake, the search did not take long. Hasegawa checked wood and leaves along the pond edge and found the animals within minutes.
“I just felt this dopamine rush, this great feeling of ‘eureka!’” he told the outlet. “It filled me with a sense of wonderment, that there are things we walk past every day like this without realizing.”
He photographed the leeches in a small setup and uploaded the images to iNaturalist. It was the first Golden Gate leech record on the platform.
A tiny predator with a long history
The Golden Gate leech is pea-sized, predatory and able to stretch its body as it moves. It feeds on flies, bloodworms and snails.
Experts believe the animal may have reached San Francisco in the 1850s, possibly carried in on plants or debris from South America.
This year’s City Nature Challenge ran from April 24 to 27. Rebecca Johnson of the California Academy of Sciences told SFGATE that 106,350 people in 754 cities submitted more than three million observations.
“The distribution of plants and animals is critically important for us to know as folks who focus on conservation,” Johnson said. “Scientists can’t be everywhere, so these sightings help us better understand species distributions and how they’re changing.”
A parent that carries its young
One detail stood out to Hasegawa: The leech’s care for its offspring. Young leeches attach beneath adults, which carry them while feeding:
“It’s interesting to think such a small, kind of primitive creature takes care of its young like that.”
For Hasegawa, the find came down to research, timing and luck. It also showed that even a busy park can hold animals many visitors never notice.
“It’s cool to see they’re still present to this day,” he said.
Sources: SFGATE
