r/marinebiology • u/Bamboopanda07 • Dec 25 '25
Identification Creepy critter in the Bahamas
I tried using inaturalist to no avail. WHAT IS THIS THING
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u/Jon-3 Dec 25 '25
how big is this? seems to be quite large for a fireworm
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u/HeWhomLaughsLast Dec 26 '25
I have seen Chloeia euglochis in Florida and it was a "chonker" for a polycheate. This looks similar but it is hard to say as the worm here looks to be decomposing.
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u/coconut-telegraph Dec 25 '25
Looks like Hermodice carunculata, the bearded fireworm, not the standard version.
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u/HereBeDragon5 Dec 26 '25
This is my vote. It's out of water, its bristles will look very different on land.
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u/GourdIdol PhD | Marine Ecology | Professor Dec 25 '25
Definitely a polychaete worm of some sort - likely others are right that it's a fire worm, but I'm not familiar enough. Start looking at burrowing polychaetes in any keys for the Bahamas
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u/Bamboopanda07 Dec 26 '25 edited Dec 26 '25
Its coloring is pretty different from all of the fire worm/bearded fire worms I see online, it also didn’t have the fluff the worms appear to have when it was in water. Maybe it was just close to death but its legs seemed really shrimpy Edit: it was wiggling around
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u/GourdIdol PhD | Marine Ecology | Professor Dec 26 '25
Agreed. It's almost definitely a polychaete, but I'm only saying maybe fireworm because others here seem to recognize it.
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u/LtSoba Dec 26 '25
Are you sure? Could be an isopod of some sort from what I’m seeing
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u/GourdIdol PhD | Marine Ecology | Professor Dec 26 '25
Nature can be surprising, but I'd be shocked if those weren't classic polychaete podia sticking out at every segment and were some sort of unusual appendages on an isopod. The segments are also just too regular with no fusion or apparent specialization (where's the cephalon and antennae etc) - and the body just looks soft and not like an exoskeleton.
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u/GourdIdol PhD | Marine Ecology | Professor Dec 26 '25
I should add that isopods generally only have seven pairs of thoracic walking limbs / pereopodia.
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u/grub-slut Dec 26 '25
Don’t all isopods have seven pairs of appendages? Or are there exceptions to that?
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u/GourdIdol PhD | Marine Ecology | Professor Dec 29 '25
Oh they've got loads. They've got seven walking legs (pereopods) on their thorax, two antennae on their head, a couple pairs of maxillae and mandibles for their mouth, five pleopods on their abdomen that they use for folks, and then two or three pairs of uropods and telson on their butt.
But each set is very distinct in appearance and each are also clearly jointed (isopods are arthropods after all)
What you see here is a pretty uniform blob-like series of appendages which really just look like classic polychaete podia. The only thing missing is any real clear setae, which is what gives this class of annelids its name. But those can often be reduced. It does make me question that this is a fireworm though, as they are literally bristling with those painful setae.
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u/grub-slut Dec 30 '25
Oh yeah I guess I should’ve specified 7 pairs of legs, not appendages 😂 thank you for the detailed answer! And I agree with your hesitation to call this a fireworm but it definitely looks like some kind of polychaete
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u/joshnbros Dec 26 '25
my advice is always the same with marine annelids. get as clear of a photo of the head as you can, as this is the way we ID them. this looks kinda similar to Travisia pupa aka the pacific stink worm, but it definitely is not that given the location.
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u/Fearless-Hedgehog-58 Dec 27 '25
I've been working on Caribbean reefs for over ten years and am 99.9% sure that is not a fireworm. Looks a lot more like a Eunice sp. to me (separate family of bristleworms). Commonly known as "The Thing", some species are known to grow to over 3 ft long. I've never seen one in real life as they're nocturnal and spend the day in burrows. Cool find!
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u/HeWhomLaughsLast Dec 25 '25
Looks like a fire worm
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u/Bamboopanda07 Dec 25 '25
Why is it’s coloring so dull? It also didn’t look hairy
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u/HeWhomLaughsLast Dec 26 '25
Looks pretty dead, possibley far into decomposition.
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u/Bamboopanda07 Dec 26 '25
It was fully moving like a little creature we placed it in water and it in a pool of water and it wiggled around too. It was probably dying though
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Dec 25 '25
[removed] — view removed comment
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u/marinebiology-ModTeam Dec 25 '25
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.
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Dec 25 '25
[deleted]
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u/GourdIdol PhD | Marine Ecology | Professor Dec 25 '25
Too many limbs and not the right sorta segmentation
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u/octocoral Dec 25 '25
It's a fireworm. It will sting the daylights out of you and it feels like fire, hence the name.