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Oceans: Coral Seas

Have you ever seen a pocket of frogspawn in a pond? It looks like a lumpy, slimy blob, right? Now imagine that a blob you thought was frogspawn turned out to be something else entirely!

Workers  at Stanley Park, in Vancouver, were surprised when exactly that happened to them. They discovered that one of the park’s ponds was full of brain-like blobs – blobs that turned out to be animals! The slimy balls are known scientifically as bryozoa (pronounced bry‑uh‑ZO‑uh), but they’re also known as moss animals, or even dragon boogers. Gross!

So what are bryozoa, then? They’re a kind of water-dwelling invertebrate. Individually, they’re microscopic – a blob like the one shown here is actually made up of thousands of little organisms called zooids. These zooids feed by using their miniature crown-like tentacles to scoop food particles towards their mouths.

Lot of species of bryozoa – including the one they found in Vancouver – use asexual reproduction (which means that they reproduce offspring without the need for a partner) to produce lots of identical zooids. These zooids are easy prey for fish and insects, so they all bind themselves to one another with sticky mucus. The result is a firm but slightly squidgy blob, up to a metre wide. Their chances of being eaten become much lower if they stick together, so they stay connected to each other in what’s known as a colony.

This type of bryozoan is normally found in western parts of the United States, so it was a bit of a surprise to come across them in Canada. Some scientists think that rising temperatures across the world have allowed them to migrate into water that was previously too cold for them.

Although this is the first time that anyone has seen these moss animals in Stanley Park, that doesn’t necessarily mean that they’re actually new to this place. Their greenish-brown colour means they are easily camouflaged in muddy, murky water, so it’s very possible that they’ve been there for years, unnoticed. In fact, bryozoa often only come to people’s attention when they grow inside water pipes, eventually blocking them!

So now you know – if you’re out and about near some water and you see a patch of frogspawn, take a closer look. You might be looking at a bryozoan!

Watch Oceans: Coral Seas to find out more about other types of small animals that live in colonies.