Some squirts
So many sea squirts can be found in the lower shore intertidal region, but without knowing a few these are likely to be overlooked. Looking often like jelly, blobs, colourful patches but no real, clear form, especially out of water, which is how they’re commonly viewed.
An observer can do themselves a favour by attempting to see these animals underwater for ID purposes, but also to enjoy seeing how they’re supposed to look.
Three commonly found species are the focus here:
star ascidian/chwistrell serennog (Botryllus schlosseri)
baked bean ascidian/chwistrell fôr goch (Dendrodoa grossularia)
lightbulb sea squirt/chwistrell wydr (Clavelina lepadiformis)
You will get an introduction here to help you recognise them when you come across them. You will then be tested.
Three squirt species
star ascidian/chwistrell serennog (Botryllus schlosseri)
©Janine Yarwood
- this sea squirt species forms star-shaped colonies, which can stand alone or become part of a larger grouping of star-shaped colonies.
- the star shape, is grouped around a central, shared out-syphon.
- can be found in many different colour forms
- attached to rocks and algae
- low shore species
- beware other brightly-coloured colonies and look for the star-shaped colonies for ID to star ascidian
baked bean ascidian/chwistrell fôr goch (Dendrodoa grossularia)
©Sue Timperley
- individual sea squirts, but can often be found growing in groups, sometimes large groups in sheltered conditions.
- short, rounded with syphons siting high on the non-attached end making it look like a teapot when viewed from the side.
- likes crevices on low shore.
- generally smooth outer surface, but which can be covered in silt.
lightbulb sea squirt/chwistrell wydr (Clavelina lepadiformis)
©North Wales Wildlife Trust
- a transparent animal which grow out from the rocks they’re attached to in long tubes
- grows in groups (small to large), attached by a basal stolon
- clear white lines can be seen along the its length and then around the opening of both in and out syphons – making them look like lightbulbs
- found under rocks and overhangs at low shore
For these squirt species there can be a few comparisons to look out for. It is important to be clear about what you’re seeing (size, colour, pattern, syphon location) and this can be something to take time over, as they’re not moving anywhere.
For the baked bean ascidian, there may be an invasive squirt which might be seen to have a similar look and therefore it’s important to get to know this one and be prepared:
- a smaller, reddish-orange sea squirt can also be found (especially attached to kelp holdfasts) and the individuals within, are attached half way down their body.
- the baked bean squirt is usually one single colour, but can be covered in sediment which is why you could confuse with another squirt called Polycarpa scuba, also take note of whether the syphons are pale and flare out at the ends, to ID P. scuba
- a final comparison can be ID’d by paying attention to the inner rim of the syphon, which in the compass sea squirt (Asteropcarpa humilis), pictured is striped.
Alternative factoids
How much more interesting can this group get? Read on and find out some more outstanding facts about our squirts. This section will not appear in the quiz as questions.
Sea squirts are part of the phylum Chordata.
They are all hermaphrodites, but they can reproduce in several ways, including cloning.
Sea squirts can be solitary, colonial (which can be attached by a type of low stem or else can share the same outer surface “test”).
Sea squirt tunics (the outer covering) can contain acids as a predator defence, they also retract their syphons for the same reason,
They squirt water to defend themselves from ingesting particles which are too large.
The next section is the quiz. Click to begin the quiz, the questions will appear below. If you get any one question wrong within each quiz page, the you will be marked as wrong for the whole page. Answers will appear one you’ve finished each question.
You will be tested on what you’ve learnt so far using the reading and video info. Don’t worry too much, as once you’ve been out on the shore, the ID features you’ve learnt about will make more sense and after a couple of visits you should feel more confident about your ID.
Good luck!