What are these things I found on the beach? BC, Canada
Posted by P05SUM@reddit | marinebiology | View on Reddit | 14 comments
Smelly worm things that seemed to be decomposing, oily substance around them.
deleted_by_reddit@reddit
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marinebiology-ModTeam@reddit
Your post was removed as it violated rule #8: Responses to identification requests or questions must be an honest attempt at answering. This includes blatant misidentifications and overly-general/unhelpful identifications or answers.
deleted_by_reddit@reddit
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marinebiology-ModTeam@reddit
Your post was removed as it violated rule #8: Responses to identification requests or questions must be an honest attempt at answering. This includes blatant misidentifications and overly-general/unhelpful identifications or answers.
grub-slut@reddit
Polychaetes 😍 I wish I could give you a more specific ID but it’s hard to make out with all the reflection on the surface. So cool! I love all the different colors
Eliciosity@reddit
Not a specialist in this area yet, but these are polychaete worms caught in I imagine the same dangerous algae bloom that’s been reported a fair bit where I am in Australia. Interested to see if anyone has any more information on this specific instance and if this should be reported
Eliciosity@reddit
For reference these are some of the Australian reports. It looks identical to me
https://www.theguardian.com/environment/2025/jun/15/deadly-algal-bloom-in-south-australias-coorong-an-environmental-eye-opener-ecologist-says
https://www.abc.net.au/news/2025-06-04/dead-marine-life-algae-bloom-found-in-coorong-sa/105370710
Neyface@reddit
Agree - I am a south Aussie marine ecologist who works in marine biosecurity. Any marine life kill events like this should be reported to the local environmental department or EPA as it can signify an event like a marine heatwave, harmful algal bloom, certain pollution events etc. It may also be worth notifying the local biosecurity agency as well to ensure this isn't a biosecurity concern (i.e., pathogen outbreak or a pest species in a boom cycle).
The taxa in the photo are definitely dead polychaetes, likely nereids. Not sure on Canadian species, though.
RoanokeSea@reddit
I wouldn't be surprised if this is a group of nereid epitokes that have washed up after their spawning session.
Some nereid polychaetes have an "atoke" stage that is more resembling a typical benthic polychaete, and then a pelagic "epitoke" stage where they undergo bodily changes such as longer "bristles" and a faster (?) metabolism ideal for swimming and finding mates, IIRC. This is all from memory from a few years ago, so lemme find a source so that you can get some more information and double check mine haha:
https://www.sciencedirect.com/science/article/abs/pii/S1096495907003545
HepCyaLater@reddit
Second this. OP if you know of any marine labs near the area, it would be great to record date/time/GPS coordinates. I would strongly advise against touching them but someone with the correct background may want to grab some for tissue samples. I’m not a marine biologist or an expert by any means but I believe benthic worms such as these are an important food source for migratory gray whales. If big die-offs of their forage base is occurring, I’m sure scientists would love to know.
P05SUM@reddit (OP)
I don't really know of anything like that besides the local aquarium, how can I find out where to report this and how to?
sabos909@reddit
They look like nereid polychaetes. Usually they burrow into the sediment and predate on other benthic infauna.
I'm not going to lie, it's WILD to see them in this density and on shore. Maybe some sort of hypoxic event drove them up and they got washed onto the rocks here? Hard to say without additional context.
Claughy@reddit
Polychaetes for sure. If I had to guess at species I'd say Alitta succinea.
BobTomJack@reddit
Polychaetes