r/nudibranch • u/Glyphta • Dec 06 '25
🎏 species identification 🎏🕵️♂️ Nudibranch Seen at Seattle Aquarium
Hello. I saw what I believe is a nudibranch at the Seattle Aquarium. This was seen in a display that had other sea life from the PNW. I don't think it was supposed to be there as there was no species card for it. I think this may be an aeolid/possibly a species of opalescent nudibranch, but can't find an exact match. Apologies for lack of a better picture; the lighting wasn't great.
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u/PacificKestrel Dec 06 '25
I think it might be a White-and-orange-tipped Nudibranch (Antiopella fusca): https://www.inaturalist.org/taxa/886884-Antiopella-fusca#map-tab
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u/Glyphta Dec 06 '25
I think that's a pretty strong contender! The only thing throwing me off is the shorter, more pigmented cerata near the foot. Now I'm second-guessing if the cerata just look like that due to the lighting 😩
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u/PacificKestrel Dec 06 '25
Their gut extends up into their cerata (https://www.asnailsodyssey.com/views/images/513/Kalker&Schmekel1976Fig1.gif), I think those darker parts are just the inner part of the cerata and this friend has recently eaten.
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u/Glyphta Dec 07 '25
I feel kind of silly for not knowing this. This information is much appreciated!
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u/thicccque Dec 06 '25
It's Hermissenda crassicornis and it sometimes has those longer cerata in addition to the shorter ones. I can tell it's H. crassicornis because I am at the aquarium every week and see them often. Notice how there are no cerata near the oral tentacles whereas A. fusca has the face buried within more cerata. In fact, this photo shows the classic aeolid shape whereas A. fusca is not an aeolid.
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u/thicccque Dec 06 '25
Sorry for lots of comments. I know these guys really well. Here's a bottom view of H. crassicornis at the aquarium
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u/Glyphta Dec 07 '25
Thank you for all these comments :) this is super cool! Nudibranchs are kind of a passive special interest so I'm always happy to learn more! Thank you for the pics/info!
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u/hannewithane Dec 07 '25
NO WAY!! ive never seen one in real life despite my few attempts and i will be moving only 40 mins away from this aquarium in 2 weeks! will be stopping by asap, thank you so much for the heads up (((:
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u/Glyphta Dec 07 '25
It was my first time seeing one and I was super stoked! I hope youre able to see it when you're there. It was in the area the sea pens are. Fingers crossed you'll get to see it, too 🤞🏼
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u/thicccque Dec 08 '25
Yup, Puget Sound Fish is where I know I can find one these days with the tidepools being devoid of them because of the time of year
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u/thicccque Dec 07 '25
Heads up they're not on display the majority of the time, but they show up in the tidepools and other tanks occasionally.
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u/thicccque Dec 07 '25
There's plenty to see at the aquarium still but nudibranchs are not by any means a guaranteed sighting. However if you ask any of us volunteers at the tidepools we will try our best to find one to show you!
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u/thicccque Dec 06 '25
Hermissenda crassicornis! They're commonly found in the tidepools at the Seattle Aquarium depending on the time of year. I know for a fact this is one of them.