• Student Mikayla Quinn holds a sea urchin. “Mikayla took the sea urchin out of the tank so we can start the process of extracting the gametes (reproductive cells) to study fertilization,” professor Isaac Skromne said. “Sea urchins look prickly, but they really aren’t. They are gentle and need to be handled with care.”

  • Quinn induces the sea urchin to release its gametes (reproductive cells) by injecting it with a solution of potassium chloride. “This solution temporarily causes the sea urchin to contract its muscles, forcing the gametes to be released,” Skromne said. “You don’t know the sex of the sea urchin until they start releasing their gametes. In this lab, we got six males before we obtained our first female.”

  • A female sea urchin deposits her eggs at the bottom of a beaker. “In the ocean, when the female sea urchin releases her eggs, she does so in the water column to promote egg dispersion,” Skromne said. “In the lab, once we induce the release of eggs, we invert the sea urchin so the eggs released drop to the bottom of the beaker.”

  • Student Emma Bender collects sea urchin eggs from the bottom of a beaker. “Emma will then dilute and spread the eggs inside a glass finger bowl prior to fertilizing them with sperm that was collected separately.”

  • Student Lindsey Armistead fertilizes sea urchin eggs. “After mounting sea urchin eggs on a microscope slide, Lindsey uses a pipette to introduces diluted sperm to the eggs,” Skromne said. “Fertilization is very quick, so everything needs to be mounted and ready in the microscope in order to observe in real time the critical moment in which a sperm fertilizes an egg.”

  • A sea urchin is born. “With the upgrades in microscopes and photographic equipment that the biology department has been doing over the last five years, we can observe the moment a sea urchin sperm fertilizes an egg in our laptop screen,” Skromne said. “The fertilization process is very fast, so we are all paying attention to capture that special and unique moment.” (Left to right: students Lindsey Armistead, Taylor Allen, Mikayla Quinn, Patrick Sutphin, and Skromne.)

  • “Studies of sea urchins provide information on fertilization and development that can be extended to all organisms,” Skromne said. “Their gametes (reproductive cells) are roughly the same size as human gametes, and the mechanisms that allow one and only one sperm cell to enter the egg’s membrane for fertilization to occur are similar to that of humans.”

How do you breed a sea urchin? Very carefully

February 21, 2022

RESEARCH & INNOVATION

Biology professor Isaac Skromne’s developmental biology class spent an afternoon last month in the lab fertilizing green sea urchins (Lytechinous variegatus), which are found along the East Coast of the United States. “We use different species of sea urchins in research laboratories depending on the season,” Skromne said. “The ones we are using come from the Florida Keys.”   

In this photo gallery, Skromne offers a look at how students handle these delicate winter-breeding Floridians.