Fungal life cycles – spores and more
Fungi are eukaryotic organisms and include yeasts, moulds and mushrooms. Some fungi are multicellular, while others, such as yeasts, are unicellular. Most fungi are microscopic, but many produce the visible fruitbodies we call mushrooms. Fungi can reproduce asexually by budding, and many also have sexual reproduction and form fruitbodies that produce spores.
Unlike plants, fungi do not produce their own food – like animals, they have to source it. So how do fungi find food?
How do fungi move?
Imagine you were as tiny as fungal hyphae, with no legs or wings or other ways of moving. If you have food, water and O2, you can grow from the ends of the hyphae and maybe branch and grow off in different directions. But being so tiny, you will only move a small amount and likely not enough to find a new source of food.
Hyphae
Soil and logs contain lots of fungal hyphae. Hyphae feed, grow and branch to form a colony and may later form a mushroom. Hyphae can also be grown on agar in the laboratory. Hyphae need O2 and produce CO2 like animals.
Fungi must leave their food to find more, and they do this not as hyphae but as spores. Spores are tiny cells that form on special hyphae and are so small that more than 1,000 would easily fit on a pinhead. Being so small and lightweight, spores can easily move unseen in the air currents, and most fungal spores are spread by the wind. You are breathing them in (and out) without noticing it, and the spores don’t cause you any problems. Some spores are also spread by water droplets from rain or in streams, and others need help from animals such as flies. Flies like stinky things, so the stinkhorn fungi have developed their spores in a really bad smelling slime. The flies eat this and then carry the spores until they later deposit them in their poo.
Stinkhorn fungus
The stinkhorn fungus hatches out of an egg-like structure and smells like rotten meat to attract flies.
If a spore lands where there is moisture and food, it may be able to grow (germinate) and produce its hyphae. As the hyphae branch and grow out in all directions from the spore, they form a circle of growth that is called a colony. Many fungi need two of these colonies to grow next to each other and to mate before that fungus is able to form any new spores and so spread further. Fungi need to produce so many spores because most spores simply die where they land, lacking water and food. Some fungal colonies can grow for a very long time and over a very large area.
Mushroom life cycle
Simplified life cycle of a mushroom. Of the many spores produced by a mushroom, only a tiny number will land where they can germinate – to produce hyphae. Hyphae of different species may grow in soil or in wood and may later form a tiny mushroom button. This then grows, and the stalk and cap expand to become a mushroom. (Some other fungi have quite different life cycles.)
Where do spores come from?
Many fungi form a fruitbody shaped as a mushroom, a shelf-like bracket, a puffball, a coral or simply like a splash of paint. The main purpose of the fruitbody is to produce spores so that the fungus can spread.
Spores of mushrooms form on special hyphae on the surface of thin gills that form in a circle hanging on the underside of the cap. The cap has a curved shape (poroharore) so that the rain droplets run off and the spores keep dry. Mushrooms must shed their spores fast as both mushrooms and spores often live for only a few days. If you pick a mushroom or other kind of fruitbody, the feeding stage of the fungus usually keeps growing in the soil or wood, but you will be stopping the mushroom’s spores from spreading to other places.
Can you see fungal spores?
Looking closer at spores
Students from Te Kura o Waikaremoana in Tūai, Te Urewera, using microscopes to look at fungi.
If you use a microscope to make the spores look much larger, you can see them clearly. But without a microscope, it’s easy to see a large group of spores. Check out the spore print activity to learn how to make a print from spores of a mushroom.
Activity ideas
Using microscopes to identify fungi parts – adapt our Ferns under the microscope activity so students can have a closer look at different fungi – and why not build in some additional learning about How microscopes magnify?
Mushroom spores – learn how to make a print from spores of a mushroom.
Acknowledgement
This resource has been from Ngā Hekaheka o Aotearoa, a science/pūtaiao guide for teachers written by Dr Peter Buchanan, Manaaki Whenua – Landcare Research; Dr Georgina Stewart, Te Kura School of Education, AUT University; and Hēni Jacob. These resources have been written from a Māori world view.
The Science Learning Hub would like to acknowledge Manaaki Whenua – Landcare Research and the writers for their permission and help to adapt this publication for the web.
An electronic version of this teacher guidebook is available to download from Huia Publishers.
