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A strange and wonderful world of starfish breeding

Male and female (right) brittle stars are tested and ready to lay eggs in William & Mary’s Allen Lab. Credit: Adrienne Berard

It takes some effort to make the brittle star feel like breeding in captivity. They need to be well nourished in total darkness and be confident that the world is ending.


“It’s like an attrition warfare,” says Orgie Davis, senior honor student at William & Mary. Davis has just finished pedaling a wheelbarrow with a small bowl of brittle stars on the second floor of William & Mary’s Center for Integrated Sciences. “After a few laps, I turn it upside down in the bowl, but it’s upside down, so I need to turn it upside down again to turn off the lights. Scientifically, there are a few. Voodoo was involved. . “

Every year before and after Valentine’s Day, a lab run by W & M biologist John Allen creates a starfish matchmaker by mimicking nature in a clever way to study the incredible life cycle of animals. I’m playing.

The research at Allen Lab focuses on the life history of marine invertebrates.Both undergraduate and graduate students study the larval ecology and evolution of a variety of organisms, including: Sea urchinSnails, flatworms, starfish, and rarely brittle stars.

Allen explained that brittle stars are difficult for researchers to obtain. Animals are very abundant in the deep sea, but rare and mysterious near the coast, avoiding light and living under rocks where only the tips of their fragile arms are exposed. If you’re lucky, efforts to set Davis’ mood will bring baby brittle stars for the lab to study.

Starfish (fish) crossing lovers — a strange and wonderful world of breeding starfish

Augie Davis ’22 prepares a mature brittle star for spawning in William & Mary’s Allen Lab. Credit: Stephen Salpukas

“It depends on how you want to anthropomorphize it,” Allen said. “They should spawn because you’re tired of them and persuading them that the world will end, or because they’re like that, you somehow make them I’m turning it on. “

One that obviously doesn’t turn on brittle stars is the other brittle stars. In the wild, male and female brittle stars rarely interact, Allen explained. However, although brittle stars and cute ones never meet, a complex breeding process takes place just below the surface of the water.

“In nature, starfish and brittle stars just throw eggs and sperm into the water, so moms and dads don’t even see each other,” Allen said. “It is their gametes, sperms and eggs that have all the fun.”

Allen explained that there is a very intimate communication system between the starfish egg and sperm. The egg is highly harmonious with certain sperm properties, especially a species-specific protein called binh dinh, allowing you to choose which sperm can enter the cytoplasm of the egg. Sperm are equally selective and swim actively only if there is an exact egg match and traces of chemicals placed by mature eggs.

Starfish (fish) crossing lovers — a strange and wonderful world of breeding starfish

Augie Davis ’22 is rowing a wheelbarrow with a small bowl of brittle stars on the second floor of William & Mary’s Center for Integrated Sciences. Credit: Stephen Salpukas

“That’s what makes these animals so fascinating to me,” Allen said. “There is this whole chemical ecology, the whole world of fertilization and choice, with no parents involved.”

He added that changes in water temperature and flow caused by climate change can change the outcome of populations of species whose survival is literally dependent on flow.

For example, the brittle star is an Arctic species. In other words, around mid-February, animals will be in a spawning state when the water is relatively warm. The female brittle star gets clues from certain changes in the environment, such as water temperature, to signal that it is time to begin releasing eggs. And while males and females never meet, brittle stars are still in the form of mating dances.

“When they do their thing, they get up in all five and twist their middle back and forth,” Allen explains the movements of male and female brittle stars when releasing gametes. And said. “They stand up on their feet and ride on the so-called boundary layer, where the water does not rise to where it is moving. Then they move and shed eggs and sperm from their armpits.”

Starfish (fish) crossing lovers — a strange and wonderful world of breeding starfish

Alexis Reece ’22 stands next to a starfish tank in the Allen Lab’s aquarium at William & Mary’s Center for Integrated Sciences. Credit: Adrienne Berard

Brittle stars and starfish are calculated against the survival of almost all animals produced during the spawning event, Allen explained. Imagine a stable population of starfish. There, moms and dads are producing just enough offspring to replace themselves for life. In large body species such as the West Coast starfish that Allen is working on, breeding females may lay 50 million eggs annually. The same female can live for decades, and if she breeds at that level for 20 years, she will lay 1 billion eggs in her lifetime, but on average only 2 will survive.

“That is, the adult starfish we find is almost literally a billionth of an event,” Allen said.

While under pressure for a successful spawning season, Allen quickly adds warnings to similar romance in the phylum Echinodermata (brittle stars, starfish, sea urchins, etc.). Creatures do not have a brain or central nervous system. Although they have thousands of eyes that are known to be sensitive to light, brittle stars do not have a sophisticated system for handling visual stimuli.

“Well, we can probably eliminate love at a glance,” Allen jokingly said. “The jury is still considering whether these animals can even be seen.”

  • Starfish (fish) crossing lovers — a strange and wonderful world of breeding starfish

    Caroline Vanduzer ’23 injects spawning-inducing hormones into starfish. Credit: Stephen Salpukas

  • Starfish (fish) crossing lovers — a strange and wonderful world of breeding starfish

    Brittle star life cycle: The lower left adult releases an egg into the water column and grows into a larva and eventually a larva. In each spin-off cycle, larval clones asexually produce new larvae. Credit: Anna Mehlhorn ’22

In the end, the brittle star romance was successful at Allen Labs, with multiple animals spawning between the two days and the night. Each breeding female lays tens of thousands of eggs, so Allen and his students will lay more than enough fragile babies to work together for their research. They use newly produced animals to study how environmental cues such as changes in temperature and salt affect cloning at the larval stage. The brittle star of each larva has the ability to asexually produce its own genetically identical clone. Understanding the process is the focus of the lab’s latest work.

Fragile babies show that one spawning season was successful, but another attempt at spawning in the lab was not a big win. When Davis was confusing and flipping brittle stars, a team of undergraduates (Caroline Vanduzer ’23, Alexis Reece ’22, Nhu-Lan Pho ’25) used more scientific and chemical induction methods to Found along the east coast and beaches of Virginia. Students injected six male and six female starfish with hormones that have been shown to stimulate spawning.

The goal was to mix gametes and study the resulting larval stage. Starfish, As a student in the previous lab accidentally discovered, cannibalize each other with an elaborate, micro-sized Darwinian display.Unfortunately for this year’s researchers, female starfish do not respond to hormones and their egg..

“They were lovers beyond the stars,” Allen laughed. “If we wanted to say that, we experienced all the right moves of romance, but fate got in the way. Of course, ultimately our goal is why they eat each other. It was to understand, so let’s be honest about science here. In nature, it can be a little weird. ”


Researchers report underwater habitats of cannibalistic echinoderms


Quote: The strange and wonderful world of breeding sea stars (February 9, 2022) is from https: //phys.org/news/2022-02-weird-world-sea-stars.html February 9, 2022. Got a day

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