Cucu & Bosmina

We proudly present the heroes in the new children’s book:

This is Cucu.


Cucu is short for Daphnia cucullata. This little creature is part of the Cladocera, or water flea, family. Water fleas are related to crustaceans, or shellfish, who you’ve certainly heard of and who you might even have eaten!

Cucu is approximately 1.5 millimetres long, and you can just about see it with your bare eye. If you want to take a closer look at Cucu, you’ll need a microscope.

Here you can see Bosmina.

Bosmina also has a scientific name, just like Cucu – Bosmina longispina. Much like Cucu, Bosmina’s also a member of the water flea clan. Bosmina is smaller than Cucu, measuring in at just 0.6 millimetres. To properly see Bosmina, you really need a microscope!

Naturally, Cucu and Bosmina live in water, after all, they are water fleas. They prefer fresh water, lakes and ponds, but they also live along the shores of the Baltic Sea.

Water fleas are also called plankton. Lots of fish and other creatures in the water eat plankton. And strangest of all, Cucu and Bosmina also eat plankton. Well, whether you even call it eating in the way we understand it is debatable, as they strain the food through slits in their stomachs. Isn’t that fascinating?

What do you think Cucu and Bosmina get up to when they’re not filtering food through their stomachs?

We don’t really know what they do or think, if they even do think. But don’t worry about that, let’s just pretend we know!

What we do know for sure is that they want to live in clean water.

We still have so much more to learn about water fleas and other little creatures floating about in seas and lakes. That’s why we’d love for you to get to know Cucu and Bosmina. Don’t they seem fun?

Follow Cucu and Bosmina on their adventures in a book and on Facebook!

Cucu & Bosmina -book

Text: Eivor Lindgård
Illustration: Satu Zwerver
Publisher: Tmi Zwerver
Pages: 44
Hard cover
Size: 21×21 cm 
ISBN: 978-952-94-1957-9 Finnish
ISBN: 978-952-94-1958-6 Swedish

The book was written by Eivor (Skini) Lindgård

whilst the drawings and photographs are the work of Satu Zwerver.


Skini recalls the early stages of creating the book:
‘I first got to know Satu 20 years ago. It became clear that she had this special passion – water fleas. Satu is an expert in algae and plankton and other tiny bugs swimming and floating in water. She works on water flea-related projects every day, having set up her own business. She’d heard that I like writing – I’d written things like children’s songs (Egils maskin (Egil’s machine) – in the 1990s, sketches, songs and a few plays, for example, for Parainen’s amateur theatre Teaterboulage ( When Satu asked me whether I’d consider writing a children’s book about plankton, my reaction was pretty much how anyone would’ve reacted: What? About plankton? Hmm.

Satu already had the two stars ready – two water fleas called Cucu and Bosmina. She’d drawn illustrations of them on a computer, which was quite something in those days. They seemed fun, and all of a sudden I realised I was seriously contemplating the water flea book. I grew more and more interested and Cucu and Bosmina began to come alive in my head! The story grew and Satu finished off the last of the pictures. With all kinds of things going on in the meantime, we have only now got round to releasing the first book, introducing our two little heroes to the world.

We’re presenting to all little (and why not bigger too) landlubbers two little water fleas – in actual fact two tiny crustaceans – Cucu (Daphnia cucullata) and Bosmina (Bosmina coregoni). Cucu and Bosmina are fighting for a cleaner living environment – in their case, water. They want to show that even if you’re really, really small, you can achieve results if you are brave enough to ask for help and take a dive into the unknown. Cucu and Bosmina’s tale is a fictional adventure story that provides all kinds of information on the world of plankton along the way, whilst reminding us how important it is to have clean water.

A little bit of the text.
A little bit of the text.

The book is intended for children aged three and up, and is suitable for being read aloud at home or at a daycare centre or school. The book works perfectly as the basis for a more in-depth conversation on environmental protection more widely. Inspired by the book, right away our test group took it upon themselves to get their own plastic recycling collection container for their daycare centre!

The book also encourages readers to collect a pot of water and have a closer look with a microscope and their own eyes to see if they can find Cucu and Bosmina in a droplet of water! In the book there are also photos taken with a microscope camera, to show the real plankton world.

A desmid, blue green algae, dinoflagellate...
A desmid, blue green algae, dinoflagellate…

On this page we will be building up a collection of all kinds of hobby activities, courses and learning materials to open the doors to the world of plankton.


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