Friday, February 19, 2021

Furry snail shells?

There's always something new ...

In a comment on my last post, a photo of two hermit crabs, blogger Sara Rall asked about snail fur. Snail fur? I'd never heard of it!

I had already spent several hours examining shells under the microscope, wondering about the multi-coloured algae growing on the hermits' shells, but it all seems to grow as if it were painted on the shells.

Pink and greens on an old shell.

Different shell, more pinks, with purple.

Pink and green, with matching anemone, on moon snail shell.

After Sara asked about snail fur, I headed for Google. Yes, there is such a thing! It's a hydroid that grows on old snail shells used by hermit crabs on both coasts of the Atlantic. Does it live here on the shores of the Pacific, too? Google didn't tell me. Only one way to find out; look for it.

Hydractina echinata, snail fur. Plate by George James Allman, Wikipedia.

Hydractinia echinata forms pinkish-brown (when alive) or plain brown (when dead) patches on gastropod shells that are occupied by a hermit crab, often near the aperture of the shell. The horny mat or hydrorhiza is about three millimetres thick. It consists of thick jagged spines that reach three millimetres in height. (Wikipedia)

I spent the day going through all my old hermit photos, then examining all the hermits in my tank, taking their photos and hauling old shells and one live, very annoyed hermit out to pin them under the microscope. Was there snail fur? Well, maybe. Or at least, something that looks like it.

Hairy hermit, with worm and bryozoans. Or are they hydroids? 2016.

Hermit with fuzzies. 2017

I found a photo of a whelk with fuzz that looks like the stuff on yesterday's hermit and on another hermit I found today in the tank.

Whelk with snail fur. Photo: By H. Zell - Own work, CC BY-SA 3.0,

Grainy hand hermit, with fuzzy shell, and an anemone in the tip.

I read that whelks also carry this hydroid, so I looked at my whelks, and found this:

White fuzz on a whelk.

Zooming in. White hairs. I don't see hydroid structures.

So: do my critters have snail fur? I don't know. But they sure have something similar. I'll look again.


Siempre hay algo nuevo ...

En un comentario sobre el último post, Sara Rall me preguntó si teníamos "pelo de caracol" aquí en la costa del Pacífico. ¿Pelo de caracol? ¡De eso, no sabía nada!

Ya había pasado varias horas viendo conchas bajo el microscopio, porque me llamaba la atención las algas de varios colores que lucían. Pero más bien parecía que estaban pintadas, con algo como algas incrustantes.

(Siguen tres fotos de conchas pintadas.)

Después de la pregunta sobre pelo de caracol, lo busqué en Google, y resulta que sí hay tal cosa. Es un hidroide que crece en conchas viejas usadas por cangrejos ermitaños alrededor del oceano Atlántico. ¿Se halla aquí en el Pacífico? Google no me dijo nada. La única manera de saber: buscarlo.

(Dibujo del hidroide Hydractina echinata.)

"Hydractina echinata hace manchas color de café rosado (en vivo) o de café (cuando está muerto) en conchas de gastrópodos ocupadas por cangrejos ermitaños, frecuentemente cerca de la boca de la concha. La capa córnea (hydrorhiza) está cerca de 3 mm. de grueso, consistente en espinas gruesas, dentadas, como de 3mm de alto." (Wikipedia)
Me pasé el dia revisando todas mis fotos viejas de ermitaños, luego examinando todos los ermitaños en mi acuario, tomándoles fotos y sacando conchas viejas y un ermitaño vivo (y no muy contento) para fijarlos bajo el microscopio. Había pelo de caracol? Tal vez. O por lo menos, algo parecido.

(Dos fotos viejos de ermitaños con algo peludo, o tal vez bryozoos.)

Encontré una foto de un buccino con pelo de caracol y se parece a lo que vimos en el ermitaño de ayer, y ahora en uno que encontré en el acuario hoy.

(Foto de Wikipedia, y foto de un ermitaño en mi tanque.)

Leí que los buccinos también pueden tener este hidriode, así que miré a mis buccinos, y esto es lo que vi:

(Fotos de un buccino con pelaje blanco.)

Entonces; ¿tendrán pelo de caracol mis animalitos? No sé. Pero sí que tienen algo parecido. Seguiré buscando.


  1. And off you go, down another "rabbit hole..."

  2. How neat! I don't know much about it, only that a friend of mine who is very experienced in mollusk ID noticed it on some shells I was asking her to identify. As they were for a bioblitz on iNaturalist I was able to count one shell three ways: the shell, the "fur" and the sign of a former hermit crab (as they don't seem to grow the hyoids without a crab present). I was intrigued.

    1. Thanks for the question about it; fascinating!


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