Northwest Dive Club

Hi,
In shallow water after a dive at Skyline in Anacortes, I spotted what I think is a Heptacarpus stylus (stiletto shrimp) on kelp with what looks like the endoparasite Kronborgia pugettensis inside it but from other resports it seems that only Heptacarpus kincaidi are hosts for that particular parasitic flatworm.
Can anyone tell if this a Kincaid's shrimp or a stiletto shrimp?

Thanks!
Karin

Hi Karin, Rich here, Glad to see you signed up. We have a resident crab expert Greg Jensen. I'm sure he will come up with the answer for you.

This coming weekend and that whole week I'll be in PT again if you guys can make it.

Looks to me like a Stiletto, I've seen several around.
Yeah, this one's red, but they come in a bunch of colors. Various shades of brown like yours, to shades of green, to red like this. Seems to be the same critter to me. The blue spots all over give it away.

Hi
yes, I've also found them in Heptacarpus stylus, and it was also at Skyline which seems to have a lot of these worms.
Greg

Thanks for the ID!

Greg Jensen wrote:Hi
yes, I've also found them in Heptacarpus stylus, and it was also at Skyline which seems to have a lot of these worms.
Greg

Thanks! It's weird that there are so many in that spot. Have you ever seen the worms' cocoons? I read that only female parasitic flatworms live in shrimp hosts. Do you know where the male parasitic flatworms live?
Karin

As far as I know males have never been found- I have the original description of the species and they weren't known at that time. Usually there's just one worm in a shrimp, but they found one that had four!
The largest worm was 120 mm long- and the shrimp only gets up to 35 mm.

To quote from the paper: "the host becomes motionless, presumably under the influence of secretions from the worm, and the worm crawls out through the anal opening after the intestine has been dislodged. The worm will only rarely find its way out between two segments. The host was not immediately killed in most cases of emergence that we witnessed in the laboratory. The heart of the shrimp continued to beat and in some cases the shrimp recovered some ability to move after the worm had emerged. The shrimp always died within a few hours, however."

I've never seen the cocoons, but they are coiled around algae, hydroids or tubeworms and "milky-white with a silky sheen" when fresh. The cocoon is longer than the worm, up to 150 mm, but only 1.1 mm in diameter.