Anyone who went to graduate school in the sciences remembers what oral exams are like. I remember not having any fun at all in mine, and by the time I was dismissed I wasn’t sure what my own name was. Fortunately, that is all ancient history and now I get to spend my time performing…
Marine invertebrates
Next step: Building a mouth
My oldest baby urchins have been actual sea urchins for eight days now. Their total age, counting from the time they were zygotes, is 58 days. When an animal undergoes a life history event as drastic as this metamorphosis, it can be tricky deciding how to determine its age. Do you count from when egg…
Learning to walk
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…
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…
Crab feed(ing)!
Anybody who has visited one of the sandy beaches in California has probably seen kids running around digging up mole crabs (Emerita analoga). These crabs live in the swash zone at around the depth where the waves would be breaking over your ankles, moving up and down with the tide. They are bizarre little creatures,…
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…
Wasting leather (star)
Until recently I hadn’t closely observed what it looks like when a leather star (Dermasterias imbricata) succumbs to wasting syndrome. When I had the outbreak of plague in my table almost 18 months ago now, my only leather star was fine one day and decomposing the next, so I didn’t get to see what actually happened…
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…
A whole lotta pink
The temperate rocky intertidal is about as colorful a natural place as I’ve seen. Much of the color comes from algae, and in the spring and early summer the eye can be overwhelmed by the emerald greenness of the overall landscape due to Phyllospadix (surf grass, a true flowering plant) and Ulva (sea lettuce, an alga)….