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

Posts from the ‘MARINE INVERTEBRATES’ category

Twelve Minutes With a Giant

In April, there were quite a few Egg Yolk Jellies around northeast Vancouver Island. I dedicated one dive to trying to find at least one and watch it for a while. You never know what you’ll learn from a species that has survived on Earth for ~500 million years.

Egg Yolk Jellies are also known as Fried Egg Jellies. Gee, I wonder how this species got their common names? 😉 Their scientific name is Phacellophora camtschatica.

They are big at up to 60 cm across the bell. But that’s no where near as big as the other common giant jelly species off our coast, the Lion’s Mane Jelly. They can be 2.5 m across the bell (the bigger Lion’s Mane Jellies are usually not near the coast).

The yellow centres in Egg Yolk Jellies are the gonads. They can be much lighter coloured than the individuals you see here. Egg Yolk Jellies have 16 large lobes that alternate with much smaller lobe-like structures giving the bell a scalloped edge. Each lobe has clusters of up to 25 tentacles making for up to 400 tentacles (25 x 16) and they can be 6 metres long.

Egg Yolk Jelly and dive buddy Linnea Flostrand on a previous dive. ©Jackie Hildering.

I was more than 30 minutes into the dive when I saw the white, slow pulsing through the soup of plankton. The jelly was swimming in my direction. I swam toward the jelly.

For twelve minutes, I watched, photographed, and learned.

I saw how the tentacles became longer and that the jelly stopped pulsing. Motionless in the water column, the tentacles spread out like a net. See that in the series of photos below?

I don’t think there was a “catch” (they feed on zooplankton, including ctenophores and other jellies). Had there been, the tentacles with the prey would have moved toward the jelly’s mouth.

I now have a much better appreciation for how they are not “passively planktonic”. They are active swimmers responding to cues in the environment. Moriarty et al., 2012 used acoustic transmitters to tag them and noted differences in swimming speed and vertical migration dependent on time of day and tidal cycle.

Jellies have sensory structures called rhopalia.

From Rebecca Helm, 2018:
Each ropalium . . . is packed with microscopic crystals at its tip. These crystals help the jelly sense up and down, by bending in the direction of gravity, similar to our inner ear. They also have a small pigment spot, which likely helps the jelly sense basic light and dark. So far, we’ve got an animal that can tell which way it’s pointing in space, and see rough light and shadow. Next we’ve got a few mystery structures, like the little bonnet-like structure surrounding the rhopalium above, which may act like a jelly nose, helping it sense chemicals in the water . . . Each rhopalium also acts like a pacemaker, helping coordinate jelly movement, similar to the way our cerebellum coordinates ours.”

And you thought they were just “going with the flow”. 💙

All photos in the above series are of the same individual.
April 19, 2025 north of Port Hardy in the Traditional Territories of the Kwakwa̱ka̱’wakw (the Kwak̕wala-speaking Peoples). ©Jackie Hildering.

For more information about the diversity of jellies on our coast, see my previous blog post “Gob Smacked” at this link. From that blog:

Lion’s Mane Jellies and Egg Yolk Jellies. are the only two common jelly species in our waters that can create a sting that irritates human skin, even when the jellies are dead. The stinging cells (nematocysts) work even when the jelly is dead or you get a severed tentacle drifting by your face. The sting from a Lion’s Mane Jelly is reported to be worst than that of an Egg Yolk Jelly.

I’ve been stung by both and clearly it’s not been enough to deter me from striving to get photos of them. But if you have far more skin exposed or are a fisher grabbing nets with many of the tentacles wrapped in them, it is reported to be very uncomfortable.

The solution to the irritation is vinegar (acid), meat tenderizer (enzyme) and I know that many fishers swear by Pacific canned milk as well. Research puts forward that vinegar is the only real solution and that urine does not work at all.

Sources:

Generalized lifecycle of a jelly from Lucas, 2001 via “A Snail’s Odyssey”.
There is alternation between a polyp with asexual reproduction and a medusa with sexual reproduction.
I have not been able to find specifics about the lifespan of Egg Yolk Jellies other than “species can have a lifespan of several years.” I have questions about why we saw quite a few dead on the ocean bottom around the same time in different locations, and what that may suggest about the lifecycle.
Dead Egg Yolk Jelly in April 2025 with dive buddy, Brenda Irving. ©Jackie Hildering.

Octopus – enshrouded

I now carry this with me.
I want you to carry it too – the knowledge of this Giant Pacific Octopus. I want you to feel at least some of what I felt. So here is a series of photos for you, with the backstory. 💙

I had my head down, slowly moving along in awe of a little species of sea cucumber that was spawning. I looked up from my focus on the small, and there, looking in my direction, was this Giant Pacific Octopus.

I backed off. The octopus backed up, into the filamentous brown algae. And then, for some 5 minutes, we looked at one another. The octopus veiled in the algae. Me, wrapped in wonder.

One of us a brief, and light-flashing visitor. The other, royalty among the invertebrates.

Octopus evolution goes back some 330 million years (before dinosaurs). That’s 1,000+ times longer than we two-legged weirdos have been on Earth (homo sapiens).

May the photos communicate some of the emotion and connect you all the more deeply to your care for this coast and our extraordinary neighbours – in how/what we buy, in our energy use, and . . . in how we vote.


Photos: April 22nd while at God’s Pocket Resort in the Traditional Territories of the Kwakwa̱ka̱’wakw (the Kwak̕wala-speaking Peoples). ©Jackie Hildering, The Marine Detective.

Egg Yolk Jelly welcome party for my Easter group at God’s Pocket Resort.

The photos below are of the wonderful, kindred divers who joined me on this trip and the outstanding crew at God’s Pocket.

Jelly-dwelling Anemone – ingest me and I will eat your gonads

An anemone species that parasitizes the jellyfish that eat them?! Then they move out, drop off and live on the ocean bottom?! And they can also move Spiderman-like from one jelly host to another?!

Yes! And in all these years this is the first time I THINK I MAY have photographed a Jelly-dwelling Anemone. They are also known as the Twelve-tentacled Parasitic Anemones and are only up to 2 cm across (Peachia quinquecapitata).

Jelly-dwelling Anemone at the stage of its lifecycle where it is NOT parasitic. That happens earlier in their lifecycle, beginning with them being planktonic larvae that get ingested by jellies ©Jackie Hildering.

Oh Nature you are so wildly varied and fabulous! Somehow seeing this remarkable little animal with a wicked lifecycle makes me feel better fortified to cope with the human-inflicted wickedness in the world. I hope it does the same for you. 💙

About Jelly-dwelling Anemones from Hanby and Lamb, Marine Life of the Pacific Northwest:

“After the larva of this anemone is ingested by a jelly, the tables are turned as it begins to feed on the host’s internal organs. Eventually, it transforms into an almost transparent anemone that hangs inside the jelly . . . Ultimately the anemone drops off and assumes a bottom-dwelling existence in a mud/sand habitat . . . “

A Jelly-dwelling Anemone at the stage of its lifecycle where it has fed on the jelly’s internal organs, including the gonads, and could move from one jelly to another. Read on! Photo ©Karolle Wall, karollewall.com
Karolle Wall, karollewall.com

Research by Spaulding published in 1972, reports that in laboratory tests, the larval anemones of this species were endoparasitic for an average of 11 days – feeding on what was in the intestines of the jelly. Then they became ectoparasitic, feeding on the gonads (sex organs) of their host. After an average of 31 days of being ectoparasites they then “had acquired their adult characteristics and dropped off the host medusa to become free-living“.

Jelly-dwelling Anemone on its way between jellyfish host and ocean bottom?
KJ Reed @Leftcoaster via iNaturalist.ca and conditions of the Creative Commons License.

Then there’s this extraordinarily engaging science communication from Dany Burgess for the Washington State Department of Ecology about this species.

Not that I would never say this species, or any other, is a monster 👹. There is nothing for humans to beware when it comes to Jelly-dwelling Anemones. Unless maybe you are living your life on a trajectory where you may get reincarnated as a jellyfish that will have its gonads eaten by this anemone species. If it is possible to sign some humans up for that fate, I currently have a list. You may have the same list.

Beware of cute little monsters:
The jelly-dwelling anemone has a spooky secret . . .
by Dany Burgess

Step aside, Alien. [the northeast Pacific Ocean] has its very own version of this famous parasitic predator, but without the terrifying claws or fangs. Like an eerily adorable child in a horror movie, an innocent-looking exterior hides the sinister intent of this squishy little monster.

Skeletons in the closet
Peachia quinquecapitata sounds like an unassuming name — even charming! But these innocuous anemones have a sordid past, and the road to adulthood is paved with the bodies of those who stood in their way. 

Shortly after hatching into the water column, larval Peachia, called planula, are eaten by jellyfish. You’d think this would be the end of the line, but it’s exactly what the baby anemones were hoping for. Instead of getting digested, the planula get comfortable in their hosts’ gastrovascular cavities and help themselves to food particles. Hey, who doesn’t like a safe place to hide, free transportation and a free meal?

Body snatchers
Unfortunately for the hosts, that free meal is just an appetizer. After a few days, the freeloading anemones begin to hunger for the main course — wait for it — the jellyfish’s internal organs. Duhn-duhn-duuuuuuuh! These pint-size parasites start with the reproductive tissue (a single baby Peachia can consume an entire jelly gonad in two days), then move on to other organs for dessert. Yum!

Weird science
This fascinating research on the Peachia life cycle was conducted at Puget Sound’s own Friday Harbor Laboratories, where scientists determined that up to 62% of one host jelly population (Clytia gregaria) was infected with these little leeches each spring. Although the planula may be able to live freely without hosts, when scientists replicated this process in laboratory culture, only the ones that were eaten by jellies survived. An amazing host-swapping behavior was also observed: the anemones were able to fire their stinging cells into new host jellies and make very slow, sticky Spiderman-esque leaps from one bell to the next. 

Beg, steal or burrow
After about a month of eating the unlucky jellies from their insides out, the anemones have had their fill. Remember the scene in Alien where the thing bursts out of the guy’s chest? Well, picture something like that, only way less disgusting. Like swollen ticks, the now fat and happy anemones drop off and go on their merry way, settling down on the sea floor and burrowing the long columns of their bodies into the mud.

Not much is known about the fate of the host jellies, but I am guessing that having your organs munched is probably harmful to your health.

Beg, steal or burrow
After about a month of eating the unlucky jellies from their insides out, the anemones have had their fill. Remember the scene in Alien where the thing bursts out of the guy’s chest? Well, picture something like that, only way less disgusting. Like swollen ticks, the now fat and happy anemones drop off and go on their merry way, settling down on the sea floor and burrowing the long columns of their bodies into the mud.

Not much is known about the fate of the host jellies, but I am guessing that having your organs munched is probably harmful to your health.

Homebodies
After spending their childhoods wreaking youthful havoc on other living creatures, Peachia adults assume new peaceful identities as model citizens. Occurring in the shallow subtidal zone of the Pacific Northwest, they spend their time with their 12 tentacles splayed out on the surface, passively waiting for food to drift by. A closer look reveals that their striped pattern is made up of delicate chevrons — very on-trend with the interior decorating crowd.

Living hand to mouth
The taxonomy crowd might appreciate Peachia for a different stand-out feature, called the conchula: a projection near the mouth that functions in feeding, and is unique to this genus. In Peachia quinquecapitata, the conchula is divided into five distinct finger-like lobes, almost like a miniature hand. And I have to hand it to these mini moochers…they definitely get away with biting the hand that feeds them!”

©Jackie Hildering

Sources:

My photos included in this blog are from April 6, 2025 near Port Hardy in the Traditional Territories of the Kwakwa̱ka̱’wakw (the Kwak̕wala-speaking Peoples).

Nudibranch named for Dr. Sylvia Earle

I am very late to this party. Back in 2020, a nudibranch was named in honour of Dr. Sylvia Earle when there was reclassification of the Yellow-margin Dorid and the research was published by Korshunova et al.

There is now Sylvia Earle’s Cadlina (Cadlina sylviaearleae).  

Despite my great admiration for Dr. Earle and for sea slugs, I did not realize these two had come together until I recently posted one of the photos you see below. Karolle Wall very kindly let me know that this was no longer a Yellow-margin Dorid (Cadlina luteomarginata).


What follows is focused on the reclassification and how difficult it is to discern these species from external characteristics. If you have an electron microscope, it will be easier. 😉 You would be able to see the differences in the radula (tooth-like structures).

What was historically Cadlina luteomarginata is now at least four described “yellow-margin dorid” species. Sylvia Earle’s Cadalina is described as a sister species to Cadlina luteomarginata. What Karolle pointed out as a helpful discerning characteristic is the space between those distinctive tubercles on the nudibranch’s side.

From Korshunova et al., 2020
“Until recently, C. luteomarginata has been considered a single species with a whitish notum and yellow marginal line with a broad range in the north-eastern Pacific from Alaska to California (e.g. MacFarland, 1966; Behrens, 1991; Behrens & Hermosillo, 2005). Present integrative morphological and molecular analysis reveals that there is considerable hidden diversity among Cadlina from the north-eastern Pacific.”

Sylvia Earle’s Cadalina (Cadlina sylviaearleae)
“Opaque whitish, with some small dorsal tubercles tipped with yellow. Rhinophores with slight yellow tint. Gills are semitransparent white, similar to ground colour . . . differs both molecularly and in a number of morphological features from all other described Cadlina species.” (Korshunova et al., 2020).

Size to at least 2,5 cm. “Known from British Columbia to Oregon”. (Behrens et al., 2022)

Differences with the Yellow-margin Dorid (Cadlina luteomarginata) as originally described by MacFarland (1905, 1966)
“Considerably less tuberculated notum [upper surface of the body], more weakly developed yellow line around notum and by patterns of the radula”. (Korshunova et al., 2020).

Size up to 8.3 cm. “Species confirmed from British Columbia to Mendocino, California, possibly to Punta Eugenia, Baja California” (Behrens et al., 2022).


More from Nudibranchs and Sea Slugs of the Eastern Pacific, 2022:
“Recent molecular analysis work has revealed a number of cryptic species with the genus Cadlina. At least four species have been previously lumped under the name Cadlina luteomarginata and it is unclear at present whether these species can be reliably identified by their external characteristics . . . All are sponge predators.”

Personal note: Reading about these species and writing this blog took me over 3 hours. Why do this? Time evaporates and I get lost for a while in science and the sea. I suppose that’s enough reason. A great bonus would be if this is of use to others too.

Sources:

Behrens, David & Fletcher, Karin & Hermosillo, Alicia & Jensen, Gregory. (2022). Nudibranchs and Sea Slugs of the Eastern Pacific.

Behrens, David. (2022). Slug Site.

Korshunova, Tatiana & Fletcher, Karin & Picton, Bernard & Lundin, Kennet & Kashio, Sho & Sanamyan, Nadezhda & Sanamyan, Karen & Padula, Vinicius & Schroedl, Michael & Martynov, Alexander. (2020). The Emperor’s Cadlina, hidden diversity and gill cavity evolution: new insights for the taxonomy and phylogeny of dorid nudibranchs (Mollusca: Gastropoda). Zoological Journal of the Linnean Society. 10.1093/zoolinnean/zlz126.

Olson, Danielle (2025). Meet Sylvia Earle, the Trailblazing Marine Biologist Who Has Spent Her Career Giving Algae Their Long-Deserved Due. Smithsonian Magazine.

Who Goes There? Sea Otter feeding pits

Who goes there?!
Or should that be – who DIGS there?!

This is the pit resulting from a Sea Otter digging after a Pacific Geoduck – a very large, very long-lived clam species.

Dive buddy Natasha Dickinson posing beside the pit to give you a better indication of its size.
Photo: January 1st, 2025, ©Jackie Hildering.

If you see a Sea Otter going up and down in the same location without coming up with prey the first time (and breaking it open on their belly), this is likely what is happening.

Sea Otter with a Pacific Geoduck.
Photo: March 27, 2021, ©Jackie Hildering.

Geoducks have very long siphons (neck or shaft) and can be buried 1 metre below the surface. So it’s quite the endeavour when Sea Otters excavate Geoducks. My photo of the deep pit should aid in understanding why this is the case!

Pacific Geoduck (Panopea generosa) – World’s largest burrowing clam. Can live to ~160 years.
Source: Goode G. B. (1880). The Fisheries and Fisheries Industries of the United States via Wikimedia Commons.
Pacific Geoduck ©Fisheries and Oceans Canada

Sea Otters are reported to be able to dive up to 5 minutes (more often ~1 minute) but that’s unlikely when exerting themselves when digging like this.

Did the Sea Otter get this Geoduck? We don’t know for sure but there was an empty shell of a Geoduck near the pit.

Note that we did not dive in the presence of Sea Otters. Diving or swimming with marine mammals is illegal in Canada.

Geoduck shell near Sea Otter feeding pit.
Photo: April 20, 2019, ©Jackie Hildering.
Another Sea Otter feeding pit and dive buddy Natasha Dickinson.
Photo: January 9, 2021 ©Jackie Hildering

Background on Sea Otters in British Columbia

Sea Otters were completely wiped out (extirpated) with the last verified Sea Otter in Canada having been shot in 1929 near Kyuquot (NW Vancouver Island).

There are now over 8,100 Sea Otters off the coast of BC (Nichol et al. 2020). How did that happen? Around 89 Sea Otters were translocated to the outer coast of Vancouver Island from 1969 to 1972 (as a mitigation measure for nuclear testing in Alaska).

The population grew (and spread out) from there. And yes, they eat a lot. Even with their incredibly dense fur (which made them so “desirable” in the fur trade), they need to fuel their furnace by eating up to 1/4 of their body mass daily to survive in the cold ocean.

More Sea Otters = more kelp forests (since they eat the urchins that eat the kelp) = more habitat, more oxygen, more food, and more carbon sequestration.

Sea Otters are recognized as a species of Special Concern in Canada.

More Information

Sea Otters
– CBC, To oblivion and back – How sea otters are radically changing the West Coast ecosystem 50 years after their return to B.C.
– Nichol, L.M., Doniol-Valcroze, T., Watson J.C., and Foster, E.U. 2020. Trends in growth of the
sea otter (Enhydra lutris) population in British Columbia 1977 to 2017. DFO Can. Sci. Advis.
Sec. Res. Doc. 2020/039. vii + 29 p.

Pacific Geoduck
– DFO, Geoduck clam
– IFLScience, What Is a Geoduck? The Ocean’s Giant Burrowing Clam
– iNaturalist.ca, Pacific Geoduck

Babies in Their Tentacles!

Oh the fabulously diverse ways that anemones reproduce! I recently documented another species where the larvae develop in the mother’s tentacles! I have even seen the babies move.

See them?!

Snakelock Anemone embryos.
Another Snakelock Anemone with embryos.

For at least the three anemone species I show here, when the males release sperm into the water column, the females do NOT release their eggs into the water. Instead, fertilization is internal. The embryos are protected as they develop in their mother’s hollow tentacles for around 2 weeks (also in areas known as the pseudospherules). Then, out into the ocean they swim as plankton, via their mother’s mouth.

There are other local anemone species where fertilization is internal too. But the embryos don’t develop in the mother’s tentacles .e.g. Brooding Anemones and Proliferating Anemones. For these species the young are “brooded” in the mother’s digestive cavity and then crawl out of her mouth and are protected under her tentacles.

In many other anemone species, like Plumose Anemones and Painted Anemones, fertilization is external. Both males and females release their gametes into the ocean at around the same time (broadcast spawning). Fertilization happens in the water column and the larvae are plankton until they settle to the ocean bottom.

And then some anemones also have asexual reproductive strategies like budding off offspring; splitting into two; or pedal laceration where a torn piece of the bottom of the anemone can grow into another anemone!

I’ve said it before . . . and you thought human sex lives were interesting. 😉

Snakelock Anemone
Cribrinopsis fernaldi
Described as a distinct species in 1976.
Crown up to 20 cm wide.

There has been considerable reclassification of local anemone species. For this species, the development of the young in the tentacles was described in research from 1976.

“Male Cribrinopsis fernaldi  (Fig. 1) in San Juan Islands, Washington release sperm in springtime.  The sperm swim or are drawn into the mouths of the females and fertilise the eggs, some of which are still in the gonads, while others are floating freely in the gastrovascular cavity, in the hollow tentacles, and in swellings around the upper outer surface of the body column.  Development proceeds within the gastrovascular cavity through gastrulation (3 days) to swimming planula larva (10 days), and then to release of the swimming larvae via the mouth (15 days).”

“Some embryos were removed from the tentacles of the adult on day 1 (early cleavage), and day 7, day 13 (planula), and day 34. These continued their development and metamorphosed and settled at the same time as the larvae which remained in the adult until natural release. It is concluded that the brooding behavior is protective rather than nutritive in function.”

Crimson Anemone
Cribrinopsis rubens 
Described as a distinct species in 2019.
Crown up to 10 cm wide.

Before I ever managed to find a member of this species with young developing in the tentacles, I often witnessed the spawning of the males. I realized that it was always only males I saw spawning (I never saw eggs being released).

As referenced above, this species was only described as a new species in 2019 having previously been confused with the Snakelock Anemone. Considering how closely the two species are related, it was expected that they would have similar reproductive strategies.

Crimson Anemone female with embryos.

Below, photos of male Crimson Anemones spawning.

Spotted Pink Anemone
Aulactinia vancouverensis
Described as a distinct species in 2013.
Crown up to 8 cm wide, and as you can see here, not always pink.

Spotted Pink Anemone female with embryos.
Male Spotted Pink Anemone spawning.

Sources:

Say Gilakas’la to the Octopus

I was given homework and I have tears in my eyes.

Last Thursday, I had the joy of teaching “All About Octopuses” to local kindergarten students.

After I had taught them, we were sitting in a circle and the children asked me if I could say hello from them to the next Giant Pacific Octopus I saw while diving.

Of course, I said yes and was really moved. But then they changed their minds.

They said I should not say “hello”. I should say “g̱ilakas’la’”.

Gilakas’la’ means “I share my breath and spirit with yours” in Kwak̓wala.

I’m not crying. You’re crying. 💙

Then, two days later, I was diving and in just 8 metres of water (25′), I chanced upon a Giant Pacific Octopus tucked away in their den. This video is the result. I hope you can hear the joy and earnestness in my voice.

Gilakas’la’ is used to welcome, greet, and give thanks.

For pronunciation listen here.
[ǥi] (la) (kas) (‘la)

Thank you dear teachers at Cheslakees Elementary School

Who’s That (Yellow) Dorid

Yes, yes I do feel somehow better now that I have compiled the following for you. Thanks for asking.

Monterey Sea Lemons and Pacific Sea Lemons are commonly confused with one another (and other yellow dorid-like nudibranchs).

On a recent dive, I was able to get photos of the two species oriented the same way AND when their gills were not retracted! I hoped that by putting these photos side-by-side, it would be useful to others to identify the species.

The easiest differences to discern who is who, are the colour of the gills (yellow or white) and whether the black markings are at the tips of some of the tubercles or not.

I’ve added photos to show (1) their very different egg masses and (2) the variation of colour within the species.

You’re welcome. 💙

The Pacific Sea Lemon is also known as the Noble Sea Lemon.

The name of the Monterey Sea Lemon (aka Monterey Dorid) does not help with clearing up confusion as it is very commonly seen far to the north of Monterey.

Both eat sponges.

The following ranges for the species are as provided by Behrens et al, Nudibranchs & Sea Slugs of the Eastern Pacific:

  • Pacific Sea Lemon: Kodiak, Alaska to Punta Banta, Baja California
  • Monterey Sea Lemon: Kachemak Bay, Alaska to Punta Banta, Baja California

Yes, one day I will another blog discerning all the yellow dorid-like nudibranchs common to British Columbia e.g. Heath’s Dorid, Geitodoris heathi.

Photos: All taken around northeast Vancouver Island, Territory of the Kwakwa̱ka̱’wakw (the Kwak̕wala-speaking Peoples), ©Jackie Hildering.

More information:

Beautiful Berthella – a sea slug that is not a nudibranch

[Update! As a result of writing this blog, I learned that the species has been reclassified AGAIN. As of ~February 12, 2024, this is no longer Berthella chacei. It is now Boreoberthella chacei. I’ve updated the text below and will just reference the species as the “White Berthella”.]

There’s a whole lot of mating going on right now with the sea slug species, Boreoberthella chacei also known as “Chace’s Sidegill” and the “White Berthella”.

Two mating White Berthellas and an egg mass.

Not a nudibranch

The Berthella are examples of sea slugs that are NOT nudibranchs. I’ve emphasized previously that “nudibranch” is not synonymous with “sea slug”.

Dive buddy Jacqui Engel and White Berthellas laying egg masses / ribbons.


The nudibranchs are just one of the seven subgroups of sea slugs (the Heterobranchia). Thereby, all nudibranchs are sea slugs. But not all sea slugs are nudibranchs. I realize those two sentences may make your brain feel sluggish. Sorry / not sorry. 😉

Characteristics shared among nudibranchs are that they are sea slugs that all DO have naked gills on their backs (hence “nudi” and “branch”) and adults DON’T have an internal shell. 

Berthellas belong in a different group of sea slugs than nudibranchs. They are sidegill sea slugs (the Pleurobranchida order). They DON’T have naked gills and DO have an internal shell. The shell of White Berthellas is thin and white and is at least half the length of their bodies. Their gills, as the name “sidegill” suggests, extend from their side.

Specifically, the gills are on the right side, between the mantle and the foot. See them in the photo above?

Perspectives on the White Berthella that show how the rhinophores extend out from under the mantle. Rhinophores are the structures extending from a sea slug’s head that allow them to smell their way around. Berthella can retract these when there is an annoyance around. Yep, an annoyance like me. You can also see the beautiful “oral veil”.

Mating time

It’s typically in February and March that I see mating and egg masses for White Berthellas near northeast Vancouver Island.

Mating White Berthellas with egg masses.


I find it a marvel that they find one another. Throughout the rest of the year I see them quite spread out from one another. There can be some within a few metres of one another but with other sea slugs species, they are often within centimetres of one another.

With other sea slug species, Nature has ensured they are often very close by the species having VERY specific prey e.g. Pomegranate Aeolids ONLY feed on Raspberry Hydroids. Thereby, there are often others of your kind, nearby on this prey.

White Berthellas are reported to feed on sponges (specifically plakinid sponges like Slime Sponge, Oscarella carmela). They don’t seem to aggregate near these sponges, maybe because they are more diffuse? They must find one another by smell detected by their rhinophores and then crawl to be within proximity (this species does not swim).

When they find one another, they appear to jostle for position in aggregations. Pairing up right-side-to-right side means that they can attach by their “gonopores” and mating can occur. Both partners become inseminated and both will lay eggs. Like other sea slugs, they are simultaneous hermaphrodites. It makes a lot of sense when you are a sea slug to maximize how many eggs are laid, especially if your young hatch out to be part of the planktonic soup of the ocean. I believe that more than one egg mass is laid per parent.

Each dot you see in the photo is an egg capsule that is only ~1.6 mm long and it contains 1 or 2 fertilized eggs. Imagine how many fertilized eggs are in the egg masses in the photos below!



The veliger larvae hatch out at the age of around 18 days in 11 to 14 degrees Celcius (it would take longer around northeastern Vancouver Island where temperatures are colder). These larvae have eyespots and shells and are around 153 micrometer long; that’s 0.153 mm! (Goddard, 1984).

Reclassification

The White Berthellahas only been recognized as being a distinct species since 2020 (Ghanimi et al, 2020). It was thought that it was one of two “morphotypes” of the California Sidegill. As mentioned in the update at the top of this blog, very recently the species has been reclassified AGAIN. it is now Boreoberthella chacei.

The White Berthella (Boreoberthella chacei) is up to 7 cm long. The body is white and has little white bumps (tubercles) randomly distributed all over its body and rhinophores. Known range is Alaska south to San Diego, California and the Sea of Japan (Behrens et al., 2022)

The California Sidegill (now also reclassified as Boreoberthella californica) is bigger on average at up to 12.7 cm. Body is white to tan and is smooth. The little white dots are uniformly spread and are not on the rhinophores. Known range is Ventura County, California to the Pacific Coast of Panama and the Galapagos Islands (Behrens et al., 2022)

The egg masses of each sea slug species are distinct. As you can see below in the compilation from the research paper, this is the case for these two species of Berthella.

Side note: How it made me smile to see that my photo of White Berthella egg masses was referenced in the research paper discerning the two species!

Leather Star and Leafy Hornmouths (marine snails) near mating and egg-laying White Berthellas.

Sources:

More photos of White Berthellas mating, and their egg masses:

A White Berthella near a Blood Star.

NatGeo Fail

[Positive update November 12: NatGeo has taken the video down from Instagram and Facebook. But, still has it on their YouTube Channel.]

Whoa!
Astoundingly and disconcertingly inaccurate!

This video is from National Geographic. The added text is mine. The first time they used the video was 5 years ago for “Alaska’s Deadliest on National Geographic TV”. NatGeo Wild posted the sensationalized and inaccurate video again on November 3, 2023 to their audiences of millions of people.


They are evidently not “encumbered” by the lack of logic and truth, despite the feedback of many. They knew how incorrect it was 5 years ago, chose to use it again, and are not heeding any of the concerns. I have provided feedback on their social media posts and am providing it here too in the hopes of countering the misinformation and holding NatGeo accountable for accuracy. They have the responsibility not to create, and perpetuate, sensationalized nonsense.

Is this worth the effort especially with so much else going on in the world? For me, it’s clearly yes. Putting this kind of illogical, inaccurate information into the world especially when perceived as an educational giant is NOT okay. It feeds the atrophying of truth, science and facts.

Deep, deep sigh.

The feedback I provided NatGeo Wild about the video:

“This content is astoundingly inaccurate. Reflect on the reality that salmon eggs are laid in freshwater, on the bottom. These jelly species do not feed on the bottom and are almost always in the ocean, not freshwater.

The eggs you say are salmon eggs being eaten by the Moon Jelly are her own fertilized eggs! In Moon Jellies, when the male releases sperm, the pulsing action of the female Moon Jelly brings the sperm in contact with the eggs under her oral arms and are brooded there.

My photo below shows a female Moon Jelly with fertilized eggs under their oral arms. The eggs she are brooding are brighter white. See them?

Female Moon Jelly brooding fertilized eggs.



Moon jellies are Aurelia labiata, maximum size is 40 cm across. 

NatGeo social media posts with this video are:
Instagram – www.instagram.com/p/CzMDQk4i3oB/ [Now taken down]
Facebook – www.facebook.com/reel/3685193188394528 [Now taken down]
Email – feedback@nationalgeographic.ca
Original YouTube post with the video – www.youtube.com/watch?v=8sO3XJY1hro