The Marine Detective

It’s a Really Good Time to Be . . .

Yesterday, we found two Sunflower Stars!

See the juvenile here to the right of my buddy Natasha? There, right beside the mating Yellow-Rimmed Nudibranchs. This Sunflower Star was in just 5 metres of water.

Today’s two Sunflower Stars are the first I have seen in twelve hours underwater over the last three months and believe me, I have been looking. I only saw one before that. They are such a rarity now. Will these two survive? I have seen waves of juveniles before and then they disappear. Their plight appears to be linked to climate change.

Hope? With action . . . yes, there is shining hope.

Without action . . . no.

Please hang in there. Please read on.

I have been struggling too, looking for escape / reprieve from global realities as another “atmospheric river” is forecast to fall on parts of our province. It is so tempting to want to hide especially if we see the problems we are facing as disparate. They are not.

I have had to remind myself of the common solutions so that I see a way forward that is not guided by the faintness of blind hope; paralyzed by fear and overwhelm; and / or obfuscated by the din of values and voices that serve the few for a brief time.

Common solutions include: to know, live and share the GAINS that come from using LESS (fossil fuels, dangerous chemicals, disposables, less consumerism generally); to speak for truth and science and to have compassion for those who cannot; to exercise our power as voters and consumers to serve future generations; and to care and act on the knowledge of connection to others – across time, cultures, distance, and species.

In short, it’s a really good time to be a good human.

I had to dig for these words for myself. As always, may they serve you too.

Photos: November 21 in Kwakwaka’wakw Territory near Port Hardy at a site where I have been monitoring sea star since 2013, ©Jackie Hildering.

*The same juvenile Sunflower Star a few minutes earlier. Notice the fish? There’s a Painted Greenling on the left and a Blackeye Goby on the right.*

For those who are not yet aware, I include the reality of Sea Star Wasting Disease (SSWD) below. A link to a summary of the research and where to report sightings is in my blog at this link.

*The other Sunflower Star we saw yesterday.*

Since 2013, more than 20 species of sea star have been impacted by SSWD from Mexico to Alaska. There is local variation in intensity of the disease and which species are impacted. It is one of the largest wildlife die-off events in recorded history. Sea stars contort, have lesions, shed arms, and become piles of decay.

Currently, some species of sea star appear to have recovered while others remain very heavily impacted. Sunflower Stars (Pycnopodia helianthoides) have been devastated and were added to the International Union for Conservation of Nature (IUCN) list as Critically Endangered. There are current efforts to have Sunflower Stars assessed by the Committee on the Status of Endangered Wildlife in Canada (COSEWIC) with hopes that they receive protection under Canada’s Species at Risk Act.

There is NOT scientific consensus about the cause. Current hypotheses focus on (i) a virus and (ii) low oxygen at the surface of the sea star’s skin maintained due to bacteria. What is consistent in is that changing environmental conditions appear to allow the pathogen (be it bacteria or viruses) to have a greater impact.

The best current source for a summary of the research is Hamilton et al (August, 2021). From that source: ” . . . outbreak severity may stem from an interaction between disease severity and warmer waters” and “Though we lack a mechanistic understanding of whether temperature or climate change triggered the SSWD outbreak, this study adds to existing evidence that the speed and severity of SSWD are greater in warmer waters”.

What I believe to be the reality off the coast of British Columbia is that there are refuges of Sunflower Stars at depth where it is colder. They spawn with some young then settling in the shallows where they may succumb to the pathogen if stressed by warmer water.

*Close up on the second Sunflower Star. This one was at about 20 metres depth.*

We Are the Weather Makers

I recently had the great joy of meeting artist Nico Kos Earle through another artistic powerhouse, Dawn Dudek.

In this meeting, Nico referenced a line from her poem “We Are the Flood” that hit me full force with its power to capture so succinctly the reality of we humans and climate change. That line is: “We are the weather makers“.

Below I share the full poem with Nico’s permission. There is so much in the words that moves me and fortifies my resolve.
May it do the same for you. 💙

Poem: Nico Kos Earle
Image: Horizon the Humpback by yours truly.

Pacific Spiny Lumpsucker – the fish, the disc, the marvel

Today I right a great wrong. For how can it be I did not have a blog featuring the Pacific Spiny Lumpsucker? This is one of the most cryptic and astoundingly adapted fish in the north Pacific Ocean.

Yesterday, I chanced upon the individual in the photo below and he is what finally catalyzed this blog. Just look at him! He is only about 2 cm long. I noticed him because he was swimming / hovering around like a minuscule zeppelin. Then he alighted on a rock, securing with the pelvic disc this species relies upon.

Pacific Spiny Lumpsucker who lives in Kwakwaka’wakw Territory near Telegraph Cove.
Photographed November 6, 2021

To be a little, round fish like this, nature had to do something to make sure you don’t roll over. You need to be able to secure, not only to rock, but to seaweeds and Eelgrass. The “solution” is that Pacific Spiny Lumpsuckers are among the fish species in which the pelvic fins have evolved into a sucker on their bellies.

This species has very small pectoral fins (even relative to body size) and does not have a swim bladder to help with buoyancy. All the more need to have the disc to be able to hold on between short hovering swims.

My video of a Pacific Spiny Lumpsucker from 2015.

Pacific Spiny Lumpsuckers don’t have scales but rather have lumpy, bony plates known as “tubercles”. Maybe these are what the “lump” in their common name refers to.

There have been many creative attempts to describe the overall appearance of Pacific Spiny Lumpsuckers from simply “cute” to “pingpong ball with fins”, to “swimming strawberries”, “underwater bumble bees”, and . . . “a fish that has quietly come to terms with looking idiotic”. Thanks Dr. Milton Love for that last descriptor. You can imagine the many jokes and allusions made about their name which “sounds like a Shakespearean insult” (comment made by Angela Flute on YouTube).

The species name Eumicrotremus orbis references their rotundity and size. Maximum known length is 12.7 cm but they are more often much smaller, around 2.5 cm.

I believe the Pacific Spiny Lumpsucker we saw yesterday was a male because mature males are reported to be dull orange to reddish brown. Mature females are pale green and have more and larger tubercles.

*Another male and you can see part of the pelvic disc. ©Jackie Hildering*

The one in Paul Wright’s video below is most definitely a male. See the egg-guarding? Male Pacific Spiny Lumpsuckers guard the eggs after fertilizing them, oxygenating them by wafting water over them and protecting them from predators. It’s reported that males die after the eggs hatch and that the females die after egg laying (average of 202 eggs, size of each egg is ~2.2 mm). Outside of when they are breeding, this is a solitary species. Appear to have a life expectancy of around 1 year in aquariums (Casey Cook, pers. com).

It is normal that Pacific Spiny Lumpsucker’s mouths are almost always open and that they appear to be panting (as you see in the video).

Video by W. Paul Wright from 2014with descriptor: “Video taken in Gibsons British Columbia. Male lumpsucker tending to newly laid eggs in discarded Ponds jar.”

Video by Ricky Belanger from 2018.

Video by Victoria High School from 2009 from their aquarium.

Further species information:

Range: Northern Washington to the Bering Sea, along the Aleutian Islands to Siberia and northern Japan. Intertidal to 575 m. Source: Lamb and Edgell, 2010.

Diet: “Small crustaceans such as gammarid andy hyperiid amphipods, along with caprellid amphipods, isopods, and cumaceans” [hooded shrimp species]. Source: Love, 2011.

*He’s not smiling. YOU’RE smiling.*
*©Jackie Hildering*

Sources:

Arita, G. S. (December 01, 1969). Sexual Dimorphism in the Cyclopterid Fish Eumicrotremus orbis. Journal of the Fisheries Research Board of Canada, 26, 12, 3262-3265.

Aquarium of the Pacific – Pacific Spiny Lumpsucker

Cook, Casey, personal communication November 7, 2021

FishBase – Eumicrotremus orbis

Lamb, A., & Edgell, P. (2010). Coastal fishes of the Pacific Northwest. Madeira Park, B.C: Harbour Pub.

Love, M. S. (2011). Certainly more than you want to know about the fishes of the Pacific Coast: A postmodern experience. Santa Barbara, Calif: Really Big Press.

I Know

The following content has been very well-received on my social media. Therefore, I am sharing it here too.

Daring to share . . .

This belongs here, on my page, where ultimately it’s about the welfare of future generations; about equity and connection.

Through recent international “realties”, to situations impacting the welfare of other species and dear friends, I have gained even more insight into how power structures enable abuse and how, at their core, it’s about keeping others small, and preferably . . . silent.

I see, and live, how disparity in power means that those working for equality, truth and justice bleed out time, energy and expense into strategizing to navigate these power systems, adding another layer of disadvantage.

I have felt anger boiling up and exhaustion creeping in. I am an older woman which means . . . I can’t.

I can’t stop.

I found myself going back to a blog I had written on “Lessons Learned from Whales – How to be a Killer Female”. Being this age, I had forgotten that I had included the text you see above beside my head.

Those of us with power must help those who have less, for that is a life well-lived. It does not mean that we have to carry it all. But imagine a world where many more of us recognize and reject the forces that strive to diminutize, divide, distract, and paralyze, and rise into our power to create positive change and help others. More of us united. That’s the world I will continue to work for.

The blog I am referencing is at this link. And yes, by writing this post and that blog, it clears my head, adds to my resolve, represents what motivates me most, and hopefully is of use to others.

#KillerFemale

A Fish as Limp as a Rag?

The fish below was found in the mouth of a Lingcod recently and created quite a stir on social media when the photos by Rugged Point Lodge were shared on social media. What species of fish was this?

I did NOT know the ID of this fish but thankfully Andy Lamb shared his knowledge that this was a juvenile Ragfish. One of the remarkable things about this species is that it is really limp, hence RAGfish

Ragfish are Icosteus aenigmaticus and can be 2.13 meter long (7 feet).

From Andy’s “Coastal Fishes of the Pacific Northwest“:
“The Ragfish usually lives in deep water an is termed a bathypelagic species. However, this fish is often found shallower as a juvenile. It’s only an occassional Pacific Northwest visitor, usually during warm weather events . . . A very limp, flappy body supported by a cartilaginous skeleton.”

Andy confirmed that sightings are vrare. Then, another juvenile was sighted thanks to Heather Lord and Nick Felch. This one was live and in the area of Clayoquot Sound.

More about the species from Dr. Milton Love’s “Certainly More Than You Want to Know About the Fishes of the Pacific Coast“:
“Icosteus means “to yield” and “bone” in Greek, referring to the limp body and “aenigmaticus means “puzzling” in Greek. “Ragfish” comes from its Über-limpness . . .

Ranges: Okhotsk Sea and Pacific Coast of Honshu to Bering Sea and Gulf of Alaska to Point Loma (Southern California). Larvae have been taken further southwards, off northern most Baja California . . . .

Salient characteristics: Oh so flabby is the ragfish; that’s the character you do wish; but if, by chance, you’re satisfied – not; we’ll tell you other things they have got. The juvies: spotted, scaled, and rounded; have pelvic fins to keep them grounded; adults lack pelvics, spots and scales; are brown and purple, both fems and males.”

With thanks too to Dr. John Ford for relaying the second juvenile Ragfish sighting.

The Creature Below the Floathouse?

How I enjoyed receiving the following mystery this week.

Be sure to have your sound on when you read and listen to the clip below.

Yes, it’s a male Pacific Harbour Seal! So many people do not realize that the male Harbour Seals establish and defend territory in the water (unlike species of sea lion and elephant seal who defend territory on land).

From Discovery of Sounds in the Sea . “Harbor seals were thought to be the least vocal of the pinnipeds. Recent studies have shown, however, that males produce underwater vocalizations during the mating season to attract females or to compete with other males. Males establish territories in the waters offshore of haul-out sites. Using underwater vocalizations, they defend their territories against other males and display to females traveling through the area. Their underwater vocalization is described as a roar with a peak frequency at approximately 1.2 kHz. Harbor seals also produce a wide variety of in-air vocalizations, including short barks, tonal honks, grunts, growls, roars, moans, and pup contact calls.”

It is remarkable isn’t it that these sounds were not known to be made by male Harbour Seals until ~1994.? This is the most common marine mammal on so many coasts and yet . . . we know so little.

Note: The person who sent me the mystery preferred to remain anonymous and that the location of the recordings not be provided. I can share that it was in the Sunshine Coast area of British Columbia. However, this underwater sound could be from ANYWHERE male Pacific or Atlantic Harbour Seals wish to pass on their genes.

See below for some of the research into Harbour Seal vocalizations.

From the research of Leanna Matthews:

“Similar to other aquatically mating pinnipeds, male harbor seals produce vocalizations during the breeding season that function in male-male interactions and possibly as an attractant for females. I investigated multiple aspects of these reproductive advertisement displays in a population of harbor seals in Glacier Bay National Park and Preserve, Alaska. First, I looked at vocal production as a function of environmental variables, including season, daylight, and tidal state. Vocalizations were highly seasonal and detection of these vocalizations peaked in June and July, which correspond with the estimated time of breeding. Vocalizations also varied with light, with the lowest probability of detection during the day and the highest probability of detection at night. The high probability of detection corresponded to when females are known to forage. These results are similar to the vocal behavior of previously studied populations.

However, unlike previously studied populations, the detection of harbor seal breeding vocalizations did not vary with tidal state. This is likely due to the location of the hydrophone, as it was not near the haul out and depth was therefore not significantly influenced by changes in tidal height.

I also investigated the source levels and call parameters of vocalizations, as well as call rate and territoriality. The average source level of harbor seal breeding vocalizations was 144 dB re 1 μPa at 1 m and measurements ranged from 129 to 149 dB re 1 μPa. Analysis of call parameters indicated that vocalizations of harbor seals in Glacier Bay were similar in duration to other populations, but were much lower in frequency.

During the breeding season, there were two discrete calling areas that likely represent two individual males; the average call rate in these display areas was approximately 1 call per minute.

The harbor seal breeding season also overlaps with peak tourism in Glacier Bay, and the majority of tourists visit the park on a motorized vessel. Because of this overlap, I investigated the impacts of vessel noise on the vocal behavior of individual males. In the presence of vessel noise, male harbor seals increase the amplitude of their vocalizations, decrease the duration, and increase the minimum frequency. These vocal shifts are similar to studies of noise impacts on other species across taxa, but it is unknown how this could impact the reproductive success of male harbor seals.

Finally, I looked at the role of female preference for male vocalizations. Using playbacks of male vocalizations to captive female harbor seals, I found that females have a higher response to vocalizations that correspond to dominant males. Females were less responsive to subordinate male vocalizations, which had a shorter duration and a higher frequency. Given that male harbor seals decrease the duration and increase the frequency of vocalizations in the presence of noise, it is possible that these vocalizations become less attractive in noise.“

*Click here for Harbour Seal vocal samples from Discovery of Sound in the Sea.*

Sources:

Discovery of Sound in the Sea (DOSITS) – Harbor Seal Sounds (Phoca vitulina).

Hanggi, E. B., & Schusterman, R. J. (1994). Underwater acoustic displays and individual variation in male harbour seals, Phoca vitulina. Animal Behaviour, 48(6), 1275–1283.

Matthews, Leanna. (2017). Harbor Seal (Phoca vitulina) Reproductive Advertisement Behavior And The Effects Of Vessel Noise. SURFACE.

Nicholson, T. E. (2000). Social structure and underwater behavior of harbor seals in southern Monterey Bay, California.

Sabinsky, P. F., Larsen, O. N., Wahlberg, M., & Tougaard, J. (January 01, 2017). Temporal and spatial variation in harbor seal (Phoca vitulina L.) roar calls from southern Scandinavia. The Journal of the Acoustical Society of America, 141, 3.)

Van, P. S. M., Corkeron, P. J., Harvey, J., Hayes, S. A., Mellinger, D. K., Rouget, P. A., Thompson, P. M., … Kovacs, K. M. (January 01, 2003). Patterns in the vocalizations of male harbor seals. The Journal of the Acoustical Society of America, 113, 6, 3403-10.

Can’t see the forest?

Can’t see the forest for the . . . fears?

Yes I am toying with this idiom to get your attention dear community.

Please read. Please take just a few minutes to check in with yourself. Please share if this resounds with you.

This week the findings of a very big, very important report went into the world. Likely you noted the heft of it; urgent words accompanied by imagery of burning, flooding and/or orange, red and yellow graphs?

Yes, I am talking about the 2021 report by the Intergovernmental Committee on Climate Change. Stay with me! What was your reaction? What did you feel? What will you do?

Take a few minutes please to reflect on this. Was it an emotional cocktail of overwhelm, fear, despondency, shutdown? This would be so understandable, especially for you who are already striving for so much socio-environmental good. But, BUT reflect on the amplified danger of this.

If we shutdown, if it is “too much”, if we bury it, or if we reject . . . where is the action? Where is the resolve and dedication to change? Where is the empowerment? Where is the future?

It is such a difficult and delicate dance in how to communicate the urgency for change while not stimulating the fear that catalyzes paralysis or for “hope” to replace action.

What to do? Feel it and then . . . do it.

We don’t need to be perfect in our actions. That notion also manipulates / debilitates us into eco-paralysis. But we do need to act.

At the very core of what needs to be done is that we need to reject that the use of less fossil fuels is about loss. We need to know the great gains achieved by our consumer and voter actions. We need to act on the knowledge of the common solutions to so many problems being achieved through less fossil fuels, less consumerism (consumerism most often fuels fossil fuel use), and more nature.

We need to model the happiness that comes from empowerment and valuing our reliance on the natural world (like the kelp and trees that absorb our carbon).

We need to embrace that disempowerment is not only individually disabling, it is the denial by those who have power over the rights and choices of others.

Care more. Consumer less.

Vote for future generations. 💙

Photo: Bull Kelp Forest in Kwakwaka’wakw Territory. Kelp forests too are in a state of change through a suite of variables that are related to climate change. More heat and/or more wind challenges their health as does the balance of their predators e.g. more grazing by urchins as a result of less Sunflower Stars. ©Jackie Hildering The Marine Detective

Do you need more red, orange and yellow graphs? Probably not, but if you do or if you want to look at the scenarios for the best future:

IPCC, 2021: Summary for Policymakers. In: Climate Change 2021: The Physical Science Basis.
Contribution of Working Group I to the Sixth Assessment Report of the Intergovernmental Panel on Climate
Change [Masson-Delmotte, V., P. Zhai, A. Pirani, S. L. Connors, C. Péan, S. Berger, N. Caud, Y. Chen, L.
Goldfarb, M. I. Gomis, M. Huang, K. Leitzell, E. Lonnoy, J.B.R. Matthews, T. K. Maycock, T. Waterfield,
O. Yelekçi, R. Yu and B. Zhou (eds.)]. Cambridge University Press. In Press.

For those who have found their way here but, for whatever reason, are not able to believe there is a climate crisis, my empathy to you. If this post provokes you, there is emotional truth in that too. There are of course deep reasons for why you believe what you do. Please know that I understand but I will not tolerate any comments that are motivated by countering precaution and/or countering science and reasoned and respectful dialogue.

Stop! That’s not garbage! Moonsnail eggs

This blog is so overdue. Over a year ago, a social media post I made about moonsnails went viral. That’s how many people valued learning that these egg collars are NOT garbage.

Below, I provide the image and text from that viral post but . . . this blog grew into so much more. Read on, I truly believe you will be moved by the marvel of moonsnails.

Text provided with the above image: “Oh oh. With recent low tides it has surfaced again that (mostly) well-intentioned people are moving or “cleaning up” moonsnail egg collars. These are not garbage. They are wondrous constructions to house and protect moonsnail embryos (of several moonsnail species on our coast).

Detail: The female moonsnail forms one layer of the collar by gluing together sand grains with mucus; then the fertilized eggs are laid on this layer and THEN she seals them in with another layer of sand and mucus!

The female forms the collar under the sand and then forces it above the sand when done. The thousands of eggs develop in the the sand-mucus matrix. The process of making the egg collar takes 10 to 14 hours and reportedly starts at the beginning of a flood tide.

As long as conditions are good, the egg collars found on beaches are likely to have embryos developing inside them (if they are still rubbery and moist). When the egg collar is intact as you seen in the images above, the young have NOT hatched out. The collar disintegrates when the larvae hatch.

The larvae are plankton for 4 to 5 weeks and then settle to the ocean bottom to develop further. There is contradictory information on how long it takes the eggs to hatch (one reliable source relays about 1 week while another reports up to 1.5 months). The moonsnail species in the photo above is the Northern Moonsnail whose shell can be up to 14 cm wide (Neverita lewisii is also known as Lewis’ Moonsnail). Photos taken in British Columbia, Canada but there are moonsnail species, and their collars, off so many coasts.”

What has catalyzed my finally also adding this content to my blog is that Mickie Donley shared her video with me showing a female Northern Moonsnail pushing her eggs to the surface.

You might be wondering how a snail THAT big can fit into their shell. Through the rapid uptake of seawater, the foot of can inflate up to four times the size of what it is when in the shell The water is expelled when moonsnails squeeze back into their shells. They need such a big foot to dig for their clam prey AND for females to construct their egg collars below the sand.

*The Northern Moonsnail is the largest moonsnail species to 14 cm long (Neverita lewisii). Males are smaller. Species reported to live to 15 year*s. *It’s the most common moonsnail species off the coast of British Columbia.*

With the entry to the shell having to be big, of course moonsnails need an “operculum”, a door-like structure that seals off the opening to the shell. See my “Shut the door” blog on opercula at this link.

*A Northern Moonsnail’s operculum – the structure attached to the bottom of the animal’s foot so that when it retreats into its shell, the opening is sealed.*

Who drilled those holes? Moonsnails!

While some whelk species also drill holes into their prey with their radula (rough tongue-like structure), when moonsnail species drill holes into their prey, there is the sunken / bevelled edge you see here. Notice too how the hole is almost always near the “umbo” of their prey’s shell (highest part). That’s also a clue that the predator was a moonsnail species, not a whelk species. See bottom of my blog at this link for more information on the radula.

From Washington State’s Department of Ecology: “The average moonsnail takedown lasting 4 days as it drills ½ mm per day. In order to speed things up a bit, the moon snail produces hydrochloric acid and other enzymes to help dissolve the shell and liquefy the clam’s insides . . . Once a perfectly rounded hole is made in the shell, the moon snail inserts its tubular, straw-like mouth and slurps up the “clam smoothie” inside. It can take another day or so for the moon snail to ingest the clam innards. Talk about delayed gratification!”

Note that I have found moonsnail shells with holes drilled into them from . . . . a moonsnail.

Who goes there?
I believe the tracks in my image below are from Northern Moonsnails.

Moonsnails clearly need to live in sandy habitats. It’s where their prey live and they also need the sand to make their egg collars.

Notice the mucus trails behind the Northern Moonsnails in the images below. While I have found no research to support this, I wonder if the the mucus may have a chemosensory role so that individuals may more easily find one another for mating.

Other moonsnail species?

There are five species of moonsnail that range from Alaska to southern California or northern Mexico.

Northern Moonsnail as shown in all the images above. Neverita lewisii is the biggest moonsnail species in the world (largest member of the Naticidae family).
Aleutian Moonsnail – Cryptonatica aleutica to 6 cm across.
Arctic Moonsnail – Cryptonatica affinis to 2.5 cm across.
Pale Arctic Moonsnail – Euspira pallida to 4 cm acrross.
Drake’s Moonsnail – Glossaulax draconis to 9 cm across and more common in California.
Note that it is acceptable to use “moon snail” and “moonsnail”.

*Aleutian Moonsnail (Cryptonautica aleutica). Notice the brown dots on the mantle in this species.*

I feel better! How about you?

There, I feel relief now that I have finally been able to commit this information about moonsnails to a blog.

I considered entitling this “Moonsnails – the Gateway Mollusc”. Why? The Northern Moonsnail is one of the first species that erupted the lava of interest within me for marine invertebrates. It started with two mysteries: I found a shell with a perfectly round hole drilled into it and . . . I found the strangest, grey, round, seemingly cemented coils of sand.

Look where it got me. 🙂

I hope this added to your knowledge and appreciation for marvellous moonsnails.

*Female Northern Moonsnail digging back into the sand after pushing her egg collar to the surface.*

More detail on moonsnail reproduction and feeding from Dr. Thomas Carefoot’s “A Snail’s Odyssey“

Reproduction:
Sexes are separate in moon snails [Neverita lewisii] and sperm transfer is direct via a penis . . . The fertilised eggs are enclosed one to a capsule and extruded from the female in a mucousy mixture that is combined with sand (left drawing below).

The colour of the egg collar depends upon the type of sand and other inclusions contained within it.

Each egg/embryo rests in a jelly matrix within an egg capsule. Moon snail veligers range in shell length from 150-200µm. The unusual shape of the egg collar results from the extruded mixture being moulded between the propodium and the shell before it sets into its final sand/jelly state (left middle drawing below).

The extrusion and moulding take place under the sand, commence at the start of flood tide, and take 10-14h. After the initial moulding is finished, the female works over the egg-collar surface one more time adding a protective sheath of sand and mucus (Right middle drawing below) and, at the same time, pushing the collar upwards to the sand surface (right drawing below).

Development within the capsule to a swimming veliger larva takes a week or so, and it is possible that the capsular fluid is utilised as food. Simultaneous with the emergence of the larvae from their capsules, the sand-mucus matrix of the collar disintegrates and the larvae swim freely in the ocean.

Feeding

Adult moon snails are strict predators and mostly eat bivalves. As many of their prey live at depths of up to 20cm or more, the snails have to burrow quite deeply to find them. Burrowing by moon snails is enabled by a large foot that is capable of inflating up to four times the shell volume through uptake of seawater. The inflation is quick, allowing fast penetration into and displacement of sand. The moon snail catches hold of its prey and hauls it to the surface to begin drilling.

Moon snails manipulate the shell of their bivalve prey so that the umbo is closest to the mouth. Whether this provides easiest handling, or whether it is to place the drill-hole directly over the bulk of soft body tissues, is not known. Another special feature of drill holes of Neverita lewisii is that they are countersunk. This feature allows the predatory records of the snails to be monitored more closely than that of, say, whelks (whose drill-holes are less distinctive). After a hole is drilled, the snail extends its proboscis hydraulically and commences scraping and eating the soft internal tissues with its radula, which is at the tip of the proboscis.

Sources:

Carefoot, Thomas. A Snail’s Odyssey

Moonsnail feeding
Moonsnail reproduction
Moonsnail locomotion

Gronau, Christian – Cortes Museum blog; The Biggest Moon of All

Lamb, A., Byers, S. C., Hanby, B. P., Hanby, B. P., & Hawkes, M. W. (2009). Marine life of the Pacific Northwest: A photographic encyclopedia of invertebrates, seaweeds and selected fishes. Madeira Park, BC: Harbour Publ.

Washington State Department of Ecology – We’re over the moon for the moon snail

Get Back I Tell You!

Here’s a post about anemone enemies (say that 5 times).

See those really long tentacles extending from the Short Plumose Anemones in the following image? These are “catch tentacles” that can extend to be up to four times longer than the feeding tentacles.

Short Plumose Anemones reach around with these specialized, extendable tentacles and THEY ATTACK if they come in contact with a different species of anemone, or others of the same species who do not have the same DNA (are not their clones).

The tip of the specialized tentacle breaks off and kills the cells in the spot where they touch their anemone enemy. Apparently this can even kill the target anemone. Short Plumose Anemones on the outside of a group of related clones are more likely to use / develop these specialized tentacles.

Short Plumose Anemones AND Giant Plumose Anemones also have nematocysts (stinging cells in their feeding tentacles) AND they have acontia. See following image. These are defensive strands filled with stinging cells that are EJECTED from their mouths or through the anemones’ bodies when threatened or stressed. These threads extend far beyond the anemone and provide longer distance defence than the stinging cells.

None of the stinging cells of local anemone species impact we humans. But how I wish I had some acontia! Yes, I have defence envy. 🙂

From Invertebrates of the Salish Sea: ” Animals on the border of a clone often develop up to 19 “catch tentacles”, which generally occur close to the mouth. These tentacles, which are larger and more opaque than the other tentacles, have special nematocysts and are unusually extensible (they can become up to 12 cm long or more). They probe the area around the anemone. While they do not respond to food, they DO fire when they contact either A. elegantissima [Aggregating Anemone] or another clone of M. senile. When it fires, the tip of the tentacle breaks off and sticks to the victim, which may retract and bend away. Tissue damage can generally later be seen in the stung area, and the attacked individual may even die.”

Image is of Giant Plumose Anemones = *Metridium farcimen* to 1 metre tall. Short Plumose Anemones are *Metridium senile* to only 30 cm tall and their crown is not as lobed. This photo is the image for this month’s WILD Calendar.

Great White! Not what you think . . .

Great White!
Not quite what you were expecting?

These are Great White Dorids. Yes, they are a species of nudibranch and the individuals featured here are mating, prowling for sponges AND succeeding in laying their astounding egg masses.

Mating Great White Dorids: Reproduction of nudibranch species is always right-side-to-right-side; attached by structures called “gonophores”. As reciprocal hermaphrodites, both parents become inseminated and lay eggs.

EACH dot you see in the egg masses (photos below) contains 8 to 12 fertilized eggs. They are laid by both parents because it makes a lot of sense to be a hermaphrodite when you are a sea slug and your eggs hatch into the sea. More fertilized eggs = more chances of some young surviving.

Even after so many years, I find the intricacy and diversity of sea slug egg masses something of jaw-dropping wonder. Not such a good thing when you are supposed to hold a regulator in your mouth while diving. 🙂

Scientific name of this species is Doris odhneri. They can be up to 20 cm long and their egg masses can be at least that size too.

Body design is classic for the sub-classification of nudibranchs that is “the dorids”. Those tufts on their hind ends are the gills and the projections on their heads (which all nudibranchs have) are the sensory rhinophores (rhino = nose). It’s how they smell their way around to find mates, food and whatever else is important in their world.

Notice in the next photo how dorid species are able to retract their gills when disturbed by the likes of an annoying underwater photographer.

Amazing too to think of the importance of smell in the sea isn’t it? Why is the individual in the following photo reared up like that? I believe it allows a better position to smell / detect the chemicals of food and/or a mate. Maybe they are even releasing pheromones? Note that is me musing. There is no research I know of to support this.

Same individual as in the first photo in this blog. I asked super sea slug expert, Dave Behrens, about this behaviour years ago and his response was: “I will agree the “rearing” is unusual in this group of dorids. Rearing is common amoung phanerobranch dorids (those that cannot withdraw their gill) . . . Although we will never know for sure, the behavior is thought to be a way for the slug to elevate itself above the substrate in search of chemical clues for its favorite prey.”

In featuring this species, the Great White Dorid, you see that not all nudibranch species are super colourful. But they are all super GREAT.

Species is also referenced as the GIANT White Dorid or Snow White Dorid, or White Dorid or White-Knight Nudibranch . . . etc. Known range is from southern Alaska to California but it’s a species I don’t see often where I dive around northeastern Vancouver Island.