Pinning down the pea crab life cycle

Until recently, the life cycle of the New Zealand pea crab had not been fully described – in particular, the larval stages were unknown. However, Jessica Feickert, a Master’s research student at Leigh Marine Laboratory, has recently identified the missing stages in the life cycle. In this video, Jessica talks about how she reared pea crab larvae in the laboratory and how she found three distinct larval stages that had not previously been seen.

Point of interest:
Like the larvae of many crustaceans, pea crab larvae swim freely in the open ocean. They can be located many kilometres from the mussels within which they will eventually settle. The larval stages can’t readily be studied in the wild and must instead be grown in the laboratory, as Jessica has done.

Teaching points:
After watching this clip, students could read the article, Life of a pea crab to learn more about Jessica’s research.

Students could annotate the image Pea crab life cycle while watching or listening to this video, and the video How pea crabs find their way home. Which stages in the life cycle have been studied by Jessica?

Transcript

Jessica Feickert (Leigh Marine Laboratory)
So I’ve been looking at the larval stages of pea crabs to try and get rid of them for aquaculture, stop them settling on the farm. So before, we’d seen the egg stages in the adults, but all the stages in between were missing.

I identified what happens after hatching, so the first three larval stages that the crab spends out in the open ocean before they develop into an adult crab. I found the larval life stages of the pea crab by doing a rearing experiment. I had them in a series of pottles, and I had no idea what they ate or what sort of environment they needed, so I just trialled different temperatures, different light phases, different foods and different foods at different life stages as well and took them as far as I could, taking a sample every 2 days. After I’d got them all the way through, which happened after a few months, I looked at these stages and saw there were three unique, like really distinct stages.

Acknowledgements:
Jessica Feickert – Leigh Marine Laboratory, Auckland University.