talking points for nature guides
Phylum Porifera
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Introducing sponges
updated Aug 08

What are sponges?
Sponges are animals!

  • It's OK if you thought sponges were plants.
    Scientists didn't even consider them animals until about 100 years ago!

  • Do you have sponges in your home? In the kitchen? Bathroom?
    Let's think about those sponges at home. They're full of holes right? Your sponges are probably made of plastic. Natural sponges are similar in structure and are also full of holes.

    To use your sponge at home, you have to squeeze it first right? The natural sponge, however, can suck water on its own! The water is filtered through the many holes in the body and tiny bits of food is gathered from the water flow.

  • But a natural sponge is usually not soft like your home sponge. The natural sponge usually has lots of spiky bits inside the body to support itself and to make itself unpleasant for other animals to eat. So please don't rub yourself with a sponge you find on the shore! You might get cuts and skin irritation.

Fascinating sponges!
Sponges come in all kinds of shapes and colours!

  • How many different kinds of sponges can you see?
    Describe their shapes, colours, patterns.

  • Who can find the biggest sponge? The most colourful?

  • Don't touch sponges!

    Sponges have no teeth and can't move. So how do you think sponges protect themselves? From being eaten? From being covered by another sponge? Yes,
    many sponges have tiny hard spikes throughout their body. Some spikes are like glass needles. Others contain chemicals that taste bad or are toxic. A sponge may also release chemicals that irritate other creatures (including other sponges) and prevent them from growing over it.
Sponges are important to the habitat
  • Sponges as shelter: many small animals hide on, under and inside sponges.

    Why is a sponge a nice place for small animals to stay?
    What do YOU like about your home? Can you find food at home? When the weather is hot do you have an aircon or fan?

    A sponge is just like your home. The sponge constantly sucks a flow of water through itself in order to filter out bits of food. So it's like having aircon! Some animals may eat the bits of food that flow in the water too. And most animals find sponges nasty to eat, so the inside of a sponge is quite safe to hide in.

  • Sponges as food: Despite being spiky and full of nasty-tasting chemicals, they are eaten by animals such as slugs, fishes and sea turtles.

  • Let's see if we can find some animals around this sponge? Be gentle when you look!

    Is the animal hiding in the sponge? Or eating it?

  • Some bigger animals in fact use sponges for protection! For example, the velcro crab sticks sponges for camouflage. The nasty tasting sponges also discourages animals from taking a bite out of it.

  • Food chain: These small animals are in turn eaten by bigger animals.
Sponges and you
Recently, sponges are attracting a lot of scientific attention as sources of interesting new chemicals with medical and other applications.

Sponge myths
  • It is NOT true that when you break up a sponge it will reassemble back together again. A broken sponge may die if the damage is extensive. Breaking a sponge not only hurts the sponge, but also the many little animals that live on and inside it.

  • A sponge is NOT a colony! In the way that a hard coral is a colony of individual animals. A sponge is a simple animal made up of a few types of cells. These cells are largely independent of one another and only loosely held together. These cells do not form tissues or organs, so a sponge does not have a mouth, digestive system or circulatory system.
Handling tips

Where to find sponges They usually grow on hard surfaces: rocks, stones, jetty pilings.

Don't step on sponges
They are living animals that take time to grow. Other small animals also live on and inside sponges.

Don't dig or rip!
Don't break up a sponge to show the internal structure or the animals living in them. Use diagrams or photos included in a guidebook if you have to show them these things. If you really HAVE to, only use sponges that have washed ashore.

Don't touch: Sponges often have spiky bits and may have unpleasant chemicals that might cause skin irritation. Worse, if visitors rub their eyes after handling a sponge!
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