Lightbulb seasquirt SWT/Rob Spray
Lightbulb seasquirt SWT/Rob Spray
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The first of a series of profiles to celebrate Suffolk’s fabulous marine wildlife and highlight the need for laws to protect UK seas – by Suffolk Wildlife Trust in partnership with Seasearch.

The lightbulb sea squirt lives communally as clusters of individuals and these communities dot the rocks and wrecks of the North Sea.

Each individual is tubular in shape and up to about 25mm (an inch) high, they often grow in groups of many tens up to bursts of several hundred.

They can frequently be seen growing on the sides of marina pontoons and moorings.

Sea squirts are filter feeders which draw water in, sieve for food particles and then ‘squirt’ it out. To do that they have two siphon openings, some squirts are individuals while others live colonially and have to share their output siphon. Can you spot the 15 separate animals in this picture?

They are spectacular as a dense cluster but are also amazingly intricate internally.

The fine, bright filaments which give them their name can take on colouration from their diet and surroundings. Usually they are quite subtly tinted but can be orange if they are growing on the rusty ironwork of an old wreck.

When sea squirts reproduce during the summer months they release a huge amount of larvae in just a few hours.

Although they look simple – you may not even think they look like animals at all - sea squirts are actually in the same phylum (major scientific group) as humans and other vertebrates – chordates!

As free swimming young they have the vestiges of a spinal chord, which they lose once they have fixed themselves down as adults.

They might seem insignificant but all marine animals contribute to the balance of an ecosystem which covers 70% of the earth, which is why Suffolk Wildlife Trust is campaigning for the protection of our Living Seas.

For more information about Suffolk Wildlife Trust call 01473 890089 or visit

The volunteer diving organisation Seasearch is run by the Marine Conservation Society and supported by The Wildlife Trusts. For details visit