Kreature Feature started off as an educational presentation at our monthly general staff meetings here at the Two Oceans Aquarium. Now in its fourth month and increasingly popular among Aquarium staff, we decided it’s only right to extend the knowledge and fun to our readers here on our website. Every month PA to Head of Education Katja Rockstroh presents a different animal that we have here at the Aquarium and tells our colleagues more about it. Usually she uncovers some rather interesting facts about the various animals she researches. She also makes sure to entertain her co-workers …

In the second edition of K’s Kreature Feature (check out the first one here), we will be looking at the fascinating creatures that are sponges.

Creatures? Sponges? Many people may think I am crazy, because the sponge that comes to mind is this one:

By Pieria (Uploader and Photographer) [Public domain], via Wikimedia Commons

However, a sponge as a creature may also be very familiar, even obvious, when this guy pops into your head:

But I do not mean either of these. I mean the mystical and often overlooked organism that should win a gold medal in the Ocean Filtering Olympics.

Sponges come in all shapes and sizes, from long and cylindrical in the tropics:

By Twilight Zone Expedition Team 2007, NOAA-OE. (NOAA Photo Library: reef3859) [CC BY 2.0 or Public domain], via Wikimedia Commons

To green and round ones in Antarctic waters:

By Steve Rupp, National Science Foundation (; exact source) [Public domain], via Wikimedia Commons

Sponges are not only diverse in shape and colour, but also in habitat.

You will find sponges in most corners of the ocean, in deeper areas where there are lots of nutrients to filter. There are up to 10 000 different species of sponge, with only 150 of them in freshwater. They clearly dominate the marine environment.

Filtration really is their main skill. They do this with pores, which cover their external surface. They suck litres of water per hour through their body cavities, where cells called collar cells grab anything they can get and use it to feed the other cells.

Because that is what sponges essentially are: a collaboration of cells working together to appropriate food, to grow and to reproduce.

To see their amazing filtration system in action, check out this video:

Going back to Spongebob Squarepants – he is actually the worst representation of a sponge there is. Sponges do not have eyes or ears. They do not have a nose or a mouth. They do not have arms or legs and they most definitely do not wear pants, a shirt and a tie. Or shoes for that matter. They also do not eat Krabby Patties.

They are one of the simplest life forms out there, yet they are extremely good at surviving.

Instead of a skeleton, sponges are made up of either spongin or spicules. Spongin is what the more squishy sponges are made out of, and these particular sponges were used as bath sponges in the olden days.

You would not want to do that with sponges made of spicules, however, and here is why:

By Rob W. M. Van Soest, Nicole Boury-Esnault, Jean Vacelet, Martin Dohrmann, Dirk Erpenbeck, Nicole J. De Voogd, Nadiezhda Santodomingo, Bart Vanhoorne, Michelle Kelly, John N. A. Hooper [CC BY 2.5], via Wikimedia Commons

Spicules are amazingly beautiful and are usually what distinguish one sponge from another, like a fingerprint. While extremely small, they could still cause rather a bit of pain if the sponge is handled roughly, and can leave the handler with a painful graze, with hundreds of these spicules still lodged in the skin. This would deter some predators from feeding on them in the wild. As it so happens, some marine turtle species feed on certain sponges.

So, even though they might not look like they do much, sponges are probably one of the hardest workers on earth, filtering away quietly, getting on with their lives.

Next time you visit the Two Oceans Aquarium, check out our sponges in the Cryptic Exhibit in the Atlantic Ocean Gallery.

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