Endless Eggs

This brightly-coloured specimen is a male Hydractinia polyp – a tiny sea creature closely related to corals, which lives on dead crab shells. Despite their small size and simple lifestyle, these animals still have some surprising similarities with humans, especially when it comes to sex. Like humans, Hydractinia have specialised sex organs which make either eggs or sperm from precursors known as germ cells. But while we have a fixed number of germ cells that are set aside before we’re born, limiting the number of eggs or sperm that can be made in a lifetime, Hydractinia keep on making new germ cells as long as they like. Understanding more about how these curious organisms organise and control their germ cells could shed light on the formation of reproductive cells in more complex animals, including humans, and help to explain what goes wrong in infertility when germ cells fail to appear at all.

See a beautiful image of a female Hydractinia by the same group here

Written by Kat Arney

Kat Arney

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Dr Kat Arney is an award-winning science writer, broadcaster and public speaker, and is the founder and Creative Director of First Create The Media.

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• Image by Timothy DuBuc, Ph.D., Swarthmore College
• Centre for Chromosome Biology, School of Natural Sciences, National University of Ireland Galway, Galway, Ireland
• Image originally published with a Creative Commons Attribution-NonCommercial 2.0 Generic (CC BY-NC 2.0)
• Research published in Science, February 2020