Close Up of Lake Merritt’s Biodiversity: Organisms of Oakland’s Crown Jewel

a nudibranch animal with orange and glowing bluish lights on the tips
This Santa Barbara Janolus (Janolus barbarensis) is a brightly-colored nudibranch, a sea slug that is usually found in more coastal waters. "[It's] a good indicator that water quality has improved in Lake Merritt. The brightly colored cerata (spikes) on its back are used to ward off predators by presenting toxins and stinging cells that they get from the organisms they eat." Photo by Damon Tighe.

Like the rest of Oakland, Lake Merritt is a microcosm of the world around us. Once in a while, the lesser-known parts of the lake are revealed — such as a little over a year ago, when a massive fish die-off surfaced thousands of sea creatures. Dozens of bat rays, hundreds of striped bass, and other fish suddenly became visible during one of the worst toxic algal blooms in decades.

However, “exotic” might not be the first word that comes to mind when thinking about the Crown Jewel of Oakland. But in many ways, it is. There are tubeworms from Australia, shrimp Hong Kong, and colorful neon-glowing nudibranchs. (And occasionally, bigger animals make their way here).

One person who’s taken the time to examine — and photographed — some of these organisms is naturalist Damon Tighe, who lived by the lake for many years.

“There’s an immense diversity of life in Lake Merritt, and some of it is really beautiful,” Tighe told Oakland Voices. Tighe, who helped document the algal bloom last year via iNaturalist, a community-sourced photo and video app, now sits on the board of the Lake Merritt Institute.

He’s hoping that by sharing some of the photos, people will look at the lake differently — and perhaps, treat it better.

Tighe estimates that 80 percent of the organisms he’s found and photographed are non-native species, likely brought in through ships. Below are just some of the highlights — visit his album for more of Lake Merritt’s animals. Tighe notes that of the organisms were taken from the lake for a brief time, photographed, and then safely released back to the lake. All of the photos were taken between 2014 and 2021.

a blueish clear jellyfish like animal against black background
“The Bell Medusa (Polyorchis penicillatus), a jellyfish-like organism is a rare sighting for Lake Merritt as these are usually associated with eel grass beds where they feed on skeleton shrimp and other small crustaceans.” Photo by Damon Tighe.
two reddish worm like creatures curled up next to each other
Marphysa, a common marine worm found under rocks and shells around the edges of Lake Merritt. “These are a favorite snack of many wading birds along the shoreline.” Photo by Damon Tighe.
a small snake-like creature with long snout against white background
The Bay pipefish (Syngnathus leptorhynchus) is closely related to seahorses. “These a very common to see at Lake Merritt, but once again, this is an organisms that takes patience to see and are usually spotted because all of sudden, a stick in a debris pile starts swimming away.” Photo by Damon Tighe.
a slug-like creature with orange feathery things
Ficopomatus enigmaticus, or tube worm. “It makes itself a calcium rich tube to hide in and then uses its feathery appendages to capture food from Lake Merritt’s water. When enough of these worms are living together, big reefs can be built just of their tubes in relatively short amounts of time. Native to Australia, these tube worms were some of the organisms that in the 1960’s gave Lake Merritt explorer Jim Carlton the idea that some marine species could be invasive and that they were likely being transported via ballast water of shipping boats all over the world.” Photo by Damon Tighe.
a large brown crab on white background
Pyromaia tuberculata, or pear crab, is a large crustacean. “The easiest way to see them is usually to watch a shallow section of the lake for a while, and all of a sudden the ground will just get up and walk away. These native crabs have been one of the few invasives that California has apparently exported to other ports around the world.” Photo by Damon Tighe.
a water slug with feather-like features on top
Hedgpeth’s Dorid (Polycera hedgpethi) is a nudibranch that’s named in honor of Oakland’s own Joel Walker Hedgpeth (1911-2006), who was an influential marine biologist, environmentalist, and author. Photo by Damon Tighe.
a little shrimp on white background
Palaemon macrodactylus is a shrimp native to parts of East Asia. “These are very common around the edge of Lake Merritt. These are UV fluorescent, so if you go out with a UV light at night its very easy to see them at the edge of the lake becuase they will glow. This is a shrimp that is eaten around the world, although I don’t know of anyone eating from Lake Merritt.” Photo by Damon Tighe.
a clear little shrimp like animal with black background and red eyes
Nebalia species. “I’ve sent a few of these out to experts, but no one seems to be confident on an identification. These are usually found when pulling up seaweed.” Photo by Damon Tighe.
a worm shaped creature with glowing blue dots and orange colors
Myrianida pachycera is originally from Australia and first appeared in California in the 1990’s. “Rare to see in Lake Merritt, but likely because of its size.” Photo by Damon Tighe.
Author Profile

Momo Chang is a freelance journalist based in the San Francisco Bay Area. She is the Oakland Voices Co-Director. Her work focuses on healthcare, immigration, education, Asian American communities, food and culture. She is a former staff writer at the Oakland Tribune. Momo has received journalism awards from the Society of Professional Journalists for investigative reporting and the Asian American Journalists Association, among others. Her work has appeared in the East Bay Express, San Francisco Chronicle, Wired, and The New York Times. Momo is primarily a print journalist who also produces audio and visual stories for documentary film and radio. She is a Senior Contributing Editor for Hyphen and formerly the Content Manager at the Center for Asian American Media (CAAM).

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