Exploring Coastal Wonders: BioMaAS Biologists Study Nudibranchs, Bumble Bees, and Snowy Plovers

You know who’s a dedicated biologist when they’re willing to get up at the crack of dawn on a Saturday to brave the cold and the wet. On Saturday, June 28, 2025, a team of biologists gathered at the foggy Maverick’s Beach parking lot to conduct a survey of the intertidal zones around Pillar Point; and to subsequently look for snowy plovers a known nesting beach Francis Beach, Half Moon Bay. In attendance were BioMaAS biologists Aaron Sunshine, Shay Duffy, Hope Martin, Whitney Gabbert, and Ivan Parr; along with Mid Peninsula Open Space District’s Marianne Rogers, California Department of Fish & Wildlife’s Dylan Winkler, and the National Estuarine Research Reserve System’s Becca Morris. Aaron’s partner Acata, who earned a degree in marine biology from Stanford, also joined the group.

Cold and soggy, the team wandered out into the rocky intertidal at 7:00 AM. At a -1.03 foot low tide, parts of the reef that are usually fully submerged underwater were exposed for beachgoers.

Figure 1. Shay Duffy admires nudibranchs on her first ever tidepool excursion

Mr. Winkler’s presence insured that the activities would be covered under a state Scientific Collecting Permit. As part of the team who worked on the potential listing of the Crotch’s bumble bee, he explained to the group how marine invertebrates like the red and black abalone had always been protected under the California Endangered Species Act, but that terrestrial invertebrates were not considered either “fish” nor “game”, and therefore lawsuits had to prove that bumble bees met the definition of “fish” under the California Endangered Species act in 2022 in order to be considered for listing. Today, we’d be looking at marine “fish”, terrestrial “fish”, and wildlife.

At first grumbling about the chill and the freezing water overtopping our boots, we headed out to the furthest reaches of the reef to look for abalone, nudibranchs, and octopuses. No abalones were observed, and this was no surprise. At least a hundred people were out on the reefs already, dropping mussels, turban snails, limpets, and sea urchins into harvest bags. The California Department of Fish & Wildlife used to patrol this beach, but official wardens have been scarce and poaching has become rampant. Possibly worse is the fact that the Fish & Game Code still legalizes high or limitless take of octopuses and other uncommon animals.

Figure 2. Hermissenda opalescens, the opalescent nudibranch

But the mood begins to improve as we take a closer look into the water. We spot the world’s largest chiton, the gumboot chiton, which looks like a crawling French roll; psychedelically-colored lined chitons; red rock crabs angrily holding up their claws in defiance; sea stars, which are making a comeback after years of wasting disease destroyed their populations; giant piddock clams with their enormous siphons peering out from holes; and the many-eyed giant scallops. But it’s the nudibranchs that steal the show. Brightly-colored sea slugs that look like sentient fireworks slithering around the tidepools are what draw various groups of onlookers tailing us through the rocks, asking us to show them “your nudis”. One group excitedly approaches, announcing, “we heard you’ve got slugs!” By the end of the morning, some 15 additional members of the public are tagging along with us and we end up finding 13 species of sea slugs. One species, Tenellia albocrusta, was new even to Ivan, who has been religiously tidepooling these beaches since the age of three.

Figure 3. Tenellia albocrusta, a rare nudibranch

As the tides begin to flood our egress back to the shore, we wade to safety and trek down to Francis Beach in Half Moon Bay. Through pea soup fog, the idea of spotting an elusive shorebird seems implausible and very quickly, the tour turns into a bumble bee survey. Dylan Winkler explains how to tell the difference between male and female bumble bees while Ivan digs up examples of the rare globose dune beetle whose squiggly sand tunnels have baffled several of the biologists for years. Finally, as the team is busily searching under rocks for bugs, someone spots a tiny shorebird hiding among the beach wrack. From a distance, we watch the plover bob at the sea and scurry away from the waves.

Figure 4. A Western Snowy Plover

Snowy plovers are listed as Threatened under the Federal Endangered Species Act, but not the California Endangered Species Act. Its presence on a State beach, however, still mandates that sections of dune vegetation are blocked off with ropes to prevent people and dogs from accidentally stepping on their eggs – exactly the color of sand and all but impossible to see. Jamie, who’d attached to our group at Pillar Point, has joined us all the way to Francis Beach. A former Point Blue biologist, they explained that studies show that snowy plovers were responding to climate change. In an ongoing study jointly published by Point Reyes National Seashore and Point Blue, authors predicted that rising temperatures would increase the likelihood for nest predation due to limiting resources. Additionally rising water levels would limit the amount of available beach for nesting. Surprisingly, however, the study is suggesting that warmer temperatures may also, in fact, improve nestling survival rates.

It was concerning that only one snowy plover, usually common at Francis Beach, was observed by this many trained eyes. But as we trudge back up the beach, someone points out that the kites being flown by the crowds of beachgoers resembled (intentionally, in fact) bald eagles and other birds of prey. Perhaps the snowy plovers were cleverly hiding away in the protected vegetation, safe from predators – real and imagined. Soggy and hungry, we headed off for lunch, stopping along the way to admire bumble bees – the flying fish of the land – in the Francis Beach native gardens.

Figure 5. Aaron Sunshine (BioMaAS), Jamie (formerly Point Blue), Dylan Winkler (CDFW), and Hope Martin (BioMaAS, sporting a pair of new Bushnells) survey for Western Snowy Plovers