Natural Perspectives: Invertebrate ‘hunting’ provides good biology lesson

Vic and I searched for marine invertebrates at the Bolsa Chica Ecological Reserve last week. Accompanying us were 18 young men and women from the Orange County Conservation Corps. Our task was to collect a variety of marine invertebrates for docents at the Bolsa Chica Conservancy to take to a group of kindergarten classes later that morning.

Although it is a lot of fun to catch these critters, I should point out that collecting animals from the ecological reserve generally is not allowed. We were working under a permit issued to the Bolsa Chica Conservancy. The crabs, snails and other critters were removed from the reserve for only a short time and treated with special care. We put them into buckets of seawater, which were then put into ice chests with ice packs to keep them cool. After the animals had served their educational purpose, they were returned unharmed to the wetlands.

A valuable by-product of the assignment was that Vic and I explained something about the biology of each invertebrate to the corps members as they collected them. So in addition to educating kindergartners, the marine critters also educated the corps members. In fact, the teachers at the John Muir Charter School that the corps members attend after work gave them two hours science credit for the morning’s activity.

Vic and I arrived at the wetlands about 7 a.m. at low tide to set a crab trap. I baited it with a frozen squid. I keep a bag of squid in the freezer, because I never know when I might need one. I bought some squid at a bait shop a couple of years ago, spread them out on a cookie sheet and froze them. Once they were frozen, I put them into a bag in the freezer so it would be easy to take them out one at a time. But over time, they had become stuck together. I had to chisel one apart from the smelly block of squid with an ice pick. What a way to start the morning.

We tossed the baited crab trap into the water, tying a thick string from the trap to a secure post on land so it wouldn’t float away on the tide. The trap has a narrow conical opening at the end of a funnel on both ends. The crabs are supposed to find their way into the trap to get the squid, but are then unable to find their way back out. Sometimes it works, and sometimes it doesn’t.

When the corps members arrived at 8 a.m., we explained that their job was to search the rocky riprap under the Warner Avenue bridge, looking for whatever was living. They spread out and asked either Vic or me about the various critters before collecting them.

They found bay mussels, littleneck clams, barnacles, horn snails, a couple of cloudy bubble snails and even some tiny anemones. The anemones were a new species for the Warner bridge area. At least I had not seen them there before. I suspected that they were strawberry anemones, which appeared at Bolsa Chica under the wooden footbridge at the south parking lot within the past decade. They’re about the size of a thumbnail, with long, slender tentacles. They form colonies on shaded rocks or other solid substrate and feed on zooplankton. Under the footbridge, you can see thousands of them growing on the algae.

The cloudy bubble snails were a great find. They tend to be nocturnal, so we had to search for them first thing. These snails have neurons at the base of their eyes that govern circadian rhythm. Impulses from these neurons cause the snails to be active at night. By day, they usually burrow into the mud to hide.

Cloudy bubble snails are about the size of a small chicken egg and are herbivorous. The meat or animal part of the snail is too large to fit entirely within the shell, so a part of it is always outside. One theory is that their fleshy mantle covers their shell to prevent barnacles from attaching. They are not popular in marine aquaria or touch tanks because they leave behind a thick slime trail that fouls the glass of the container that they’re in.

That morning, we were lucky enough to find two still out and about. Because cloudy bubble snails are so slimy, I delighted in passing them around to the unsuspecting corps members, who reacted with disgust. I just love biology.

Our next destination was the tidegates. Our main target there was the California sea hare, a mottled brown marine slug that grows almost as large as a football. The corps members spotted a small one and collected it from the rocks. It was about 5 inches long, which meant that it was probably about 3 to 4 months old.

Sea hares start life from tiny eggs that are laid in yellowish spaghetti-like strands. Larvae hatch from the eggs after about 12 days and are free-floating zooplankton for a month. The larvae then undergo a metamorphosis, settle down onto red algae and change into slugs that glide around on the ocean bottom for the rest of their life, which is about one year.

Sea hares are hermaphrodites, which means that each individual can act simultaneously as both male and female. Many marine invertebrates reproduce by external fertilization, shedding eggs and sperm into the water. But sea hares reproduce by internal fertilization.

An individual sea hare extrudes its male part from where its chin would be if it had a chin, and inserts it into the female part of another sea hare, which is about where its shoulder blades would be if it had shoulder blades. And while a sea hare is mating with the one in front, another sea hare will crawl on its back and mate with it. Each one lays its cream to yellow egg mass onto the rocks or algae. Sea hare eggs are extremely toxic, so don’t handle them.

During the spring and summer, the sea hares form mating circles of four to 10 individuals with each one mating with the one in front and behind at the same time. The corps members said that was sick. Well, yeah, if it were happening in humans. But each species has its own set of behaviors, and that’s normal behavior for sea hares. Marine biology is a wild and wacky world.

The corps members caught a number of lined shore crabs by hand, which surprised me. Generally, the crabs are far too fast to be caught that way. Good thing they caught them, though, because our crab trap came up empty of crabs. But we did manage to trap a 4-inch-long goby, which is a bottom-feeding fish.

We had a very successful morning and were able to find a lot of interesting animals for the kindergarten classes. The lucky corps members who participated in the marine invertebrate hunt were Uzniel Garcia, Chad Bedsaul, Antonio Luevano, Steve Olivares, David Dettevuera, Maria Berber, Johnny Lopez, Bryan Garcia, Annette Gonzalez, Anthony Pipkin, Anthony Arreola, Christopher Romo, Bryan Ledesma, Karen Bermudez, Roger Flores, Andrew Arreola, Maria Gomez and Ruben Garcia. The supervisors accompanying them were Gil Morales and Rodney Gagnon.

VIC LEIPZIG and LOU MURRAY are Huntington Beach residents and environmentalists. They can be reached at LMurrayPhD@gmail.com.