How mussels spawn

Like many marine animals, green-lipped mussels mate by broadcast spawning – the simultaneous release of eggs (from female mussels) and sperm (from male mussels) into the water. In this video, Andrew Jeffs (Leigh Marine Laboratory) describes what happens during a spawning event and demonstrates the key visual differences between male and female green-lipped mussels.

Focus question: Why do some green-lipped mussels have orange flesh while others have white flesh?

Teaching point: Have your students view the video without sound, then write down (or share with a partner) what they think is happening. They can then watch again with the sound on.

Transcript

Professor Andrew Jeffs (Leigh Marine Laboratory) This is a male mussel. You can see from the very white milky colour – that’s sacs of sperm which the mussel’s accumulating ready to release when it gets the right signal. And over here is a female mussel, and you can see she’s quite different. She’s got a big area of bright orange colour, and this will get brighter and brighter orange as the eggs mature and are ready to be released.

So typically, mussels are found in a bed where there’s lots and lots of mussels all tightly scrunched up together. And something will happen like a storm, which stirs up the water, and it will trigger some mussels to start spawning, releasing sperm, and then the others will start releasing eggs, and then everyone’s at it. Everyone’s hurling sperm and eggs into the water, and then the sperm are looking for the eggs and they’ll fertilise them, and the fertilised eggs then become swimming larvae or little tiny swimming babies of mussels.

Acknowledgements: Professor Andrew Jeffs, Oliver Trottier – Leigh Marine Laboratory, Auckland University. Mass Audubon Joppa Flats Education Center, Massachusetts. www.massaudubon.org/joppaflats