Spirorbis spirorbis
ANNELIDA
Serpulidae
🌀🐚 You have probably seen these small white swirls on algae or under rocks before, but did you know they were worms?!
🪱 Spirorbis are small sedentary worms, living in their own calcium carbonate coiled tube shell. Just like earthworms in your garden, they belong to annelids (a phylum of +22 000 species) and they have a segmented body.
⏰ 🌀The rotation of the swirl is specific to each species! This one, Spiorobis spirorbis is always coiled clockwise and super common on this brown algae (fucus).
🫣🌊 They can completely retract within the tube, sealed by the operculum. It protects them from predators and turbulent tides but also from desiccation when they get out of the water…
🌀🐚 The Spirorbis tube worms build their own calcareous tube using special glands in their upper body segment. Inside the tube, the body is segmented, like all annelid worms 🐛!
👑 🫁The branchial crown is not only their primary feeding structure, it is also their respiratory organ! It’s like having lungs on the top of the head, how crazy is that?!
🔆👄 Just like bryozoans, they are filter feeders and use their specialized crown of tentacles around the heard to catch planktonic particles in the water column. Seems like a trending way to eat around there!
🔐🫣 The operculum (visible on the right of the top picture) seals the opening of the tube to protect the worm from desiccation at low tide.
Sources
- WoRMS
- Doris
- Brinkmann N. & Wanninger A. (2009). Neurogenesis suggests independent evolution of opercula in serpulid polychaetes. BMC evolutionary biology. DOI: 9. 270. 10.1186/1471-2148-9-270