Imagine spending your entire life up in the water column as a creature of the plankton. You use cilia to swim but are more or less blown about by the currents, never (hopefully!) encountering a hard surface, and feeding on phytoplankton and other particulate matter suspended in the water. Then, several weeks into your life’s…
Tag: sea urchins
Taking their sweet time
After much teasing and titillation, my urchin larvae have finally gotten down to the serious business of metamorphosis. It seems that I had jumped the gun on proclaiming them competent about a week ago, or maybe they were indeed competent and just needed to wait for some exogenous cue to commit to leaving the plankton for…
Competence
In the parlance of invertebrate zoologists, competence is the state of development when a larva has all of the structures and energy reserves it needs to undergo metamorphosis into the juvenile form. In the case of my sea urchins, this means that they have four complete pairs of arms, each with its own skeletal rod, and…
Perfection! And yet….
Thirty-one days ago, on 20 January 2015, I spawned purple sea urchins (Strongylocentrotus purpuratus) and generated six jars of larvae. I’ve been examining the larvae twice a week ever since. At first they were doing great, developing on schedule with no appreciable abnormalities or warning flags. Then, at about Day 24, the cultures began crashing for…
Larvae as . . . particles?
On another glorious afternoon low tide the other day, with the help of a former student I collected six purple urchins, Strongylocentrotus purpuratus. Given that we’re in about the middle of this species’ spawning season, I reasoned that collecting six gave me a decent chance of ending up with at least one male and one…
Immaculate conception
I’ve shown you how sea urchin eggs are fertilized in the lab, and you’ve watched the fertilization membrane develop in real-time. One day a few years ago, my colleague, Betsy, and I set up shop to spawn urchins. We do this just about every year because it is super fun and we both enjoy watching…
Let there be life!
One of the all-around coolest things I do with my students is spawn sea urchins to show them fertilization. We can actually watch fertilization occur under the microscope. And since the early stages of development are the same in sea urchins and humans the students get to see how their own lives started–not in dishes…