Join me in the cold, dark, life-sustaining NE Pacific Ocean to discover the great beauty, mystery and fragility hidden there.

Posts tagged ‘classification’

Shelled Sea Slug! A small mystery solved.

Here’s a bit of a mystery that took me more than a year to sort out.

On April 27th, 2016, I found this egg mass while diving in Browning Pass with God’s Pocket Resort. This is to the north of where I live and is somewhere I only have the joy of diving a couple of times a year.

Mystery sea slug egg mass among horseshoe worms. (From Neil McDaniel re. worm ID – “they are Phoronids most likely Phoronopsis harmeri” – April 2016. ©Jackie Hildering.

I recognized it was likely a sea slug egg mass but did not know the species.

More than a year passed. On May 7th, 2017, I had a chance to dive the same site again and so hoped to find the species who laid the eggs. We quickly swam to where I had found the egg mass the year prior, into the shallows (~5m), and hovered over the ocean bottom strewn with bits of shell remains.

And I found these . . .

Tiny snail-like animals, plowing through the bits of shell and urchin remains. One, two, three . . . six of them!

I tried to calm myself down, to get photos, and to watch how, despite their soft bodies and the sharp bits of shell, they were able to even push under the surface.

They were Stripe Barrel Shells (Rictaxis punctocaelatus) with shells only to 2 cm long)!

A “Striped Barrel Shell” beside an urchin spine, giving a sense of how small these animals area. ©2017 Jackie Hildering.

These are often mistaken as being a marine snail (prosobranch) like a whelk but they are a type of “bubble shell” sea slug. They are also not nudibranchs. They have a thin shell and do not have “naked gills”. Therefore they do not belong in the “nudibranch” sub-group of sea slugs (opisthobranchs).  For the classification super nerds, see this link or the graphic at the end of this blog for my attempt at offering clarity.

Plowing down into the shell debris! ©2017 Jackie Hildering.

Please know that I am not suggesting that this is a rare species. Rather, they are hard to find. Their size makes them hard to see; divers often do not target the sand or shell-covered bottoms where they live; AND . . . . they are often just under the surface.

I was incredibly fortunate therefore to find them out and about – maybe feeding on algae and/or trying to smell where a mate might be (and we think WE’RE challenged in finding a partner!)

And how about those eggs? Are they a match?

Yes, they are! I was able to confirm this thanks to the knowledge and brilliant documentation of Jeff Goddard on the Sea Slug Forum (see below).

Source: Sea Slug Forum; Jeff Goddard. 

 

Another little mystery solved.

Another big influx of wonder about the life in the NE Pacific Ocean! 🙂


My attempt at summarizing the cassification of the group to which sea slugs belong.
Last updated 2020-04-17. Source: World Register of Marine Species.


For an additional blog about another bubble shell sea slug in the NE Pacific Ocean see – “Slugs that Fly? The Great Winged Sea Slug”

Porpoise-full Blog!

This, like my “You Otter Know” blog, is aimed at clearing up species confusion and offering some support to my fellow marine educators.

Yes, I am writing this for much needed educational porpoises. Sorry! I will attempt to restrain myself from further bad puns (but I am counting on you, the readers, to come up with some doozies).

Oh the number of times I have had the joy of an exchange like this:
Me: “Look, a porpoise!”
Response: “Ja, ja, een delfin!” or “Oui, oui, un dauphin” or “Ja, ja,  een dolfijn” or “Yes, yes, a dolphin!”.
Me (armed with images like those below): “Nein – een schweinswal” / “Non – un marsouin” / “Nee – een bruinvis” / “Nope – it really is a porpoise!”

It is so understandable that there is significant confusion. The words dolphin and porpoise were, colloquially, used as if they were synonyms into at least the 1970s.

But, dolphins and porpoises are more distinct than lions and tigers.  Lions and tigers are not only in the same family but in the same genus. Dolphins and porpoises are in different families, having diverged around 15 million years ago.

_JH11109

That’s no dolphin! It’s a Dall’s Porpoise. ©2015 Jackie Hildering.

The differences between porpoises and dolphins span from fin and head shape, to behaviour, vocals and average group size.

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