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

Posts from the ‘Anemones’ category

Sea of Love – Broadcast Spawning!

Most often, divers prefer good visibility. But oh to have the good fortune to happen to be in the water when marine invertebrates are spawning!

I’ll never forget the first time the seas suddenly turned white and these green packets drifted by my mask.

Orange sea cucumber egg pellet

Egg pellet from an Orange Sea Cucumber. ©2014 Jackie Hildering.

 

I was euphoric that I happened to be in the water when Orange Sea Cucumbers (Cucumaria miniata) and Giant Plumose Anemones (Metridium farcimen) were broadcast spawning. Witnessing the magnitude of this great force that ensures these species will survive is as awe-inspiring as witnessing the annual spawn of herring or salmon.

Female orange sea cucumber about to release an egg pellet. Click to enlarge. © 2014 Jackie Hildering; www.themarinedetective.ca

Female Orange Sea Cucumber about to release an egg pellet. ©2014 Jackie Hildering. 

The same female orange sea cucumber 1 minute later, releasing the egg pellet. Click to enlarge. © 2014 Jackie Hildering; www.themarinedetective.ca

The same female Orange Sea Cucumber 1 minute later, releasing the egg pellet.  ©2014 Jackie Hildering. 

Another spawning male. Orange sea cucumbers can also be this darker colour. Click to enlarge. © 2014 Jackie Hildering; www.themarinedetective.ca

Spawning male Orange Sea Cucumber. Species can also be this darker, brownish colour. ©2014 Jackie Hildering. 

 

During broadcast spawning, invertebrate males and females each release their sex cells into the water column – in astoundingly copious amounts.

You can imagine how many gametes must be released for there to be a chance of fertilization and for enough of the resulting larvae to survive and not to be eaten by the many filter feeders such as barnacles, anemones and sea cucumbers!

Not only was it the male Orange Sea Cucumbers that were making the cloudy with their astounding numbers of gametes. The Giant Plumose Anemones were broadcast spawning too. Males releasing slow, white jets of their sperm and females then releasing their pinker egg masses. (Note that Giant Plumose Anemones can reproduce asexually as well by pedal laceration but broadcast spawning allows for diversity through sexual reproduction). [Update 2017: Photos added showing contrast between male and female gamete “packages” with thanks to Neil McDaniel for confirming the pink masses are eggs.]

Spawning giant plumose anemone. Click to enlarge. © 2014 Jackie Hildering; www.themarinedetective.ca

Spawning male Giant Plumose Anemone. © 2014 Jackie Hildering.

Giant Plumose Anemones spawning. Males release the whiter masses of gametes while the females’ masses of eggs have a pinkish colour. See them here? ©2017 Jackie Hildering.

Giant plumose anemone releasing gametes. Click to enlarge. © 2014 Jackie Hildering; www.themarinedetective.ca

Close-up of a male Plumose Anemone spawning. ©2014 Jackie Hildering. 

 

It is of course a good strategy to have males and females living in close proximity and that timing is everything! The spawn must be synchronized. To release sex cells when others of your kind are not doing so, would be a very failed reproductive strategy indeed.  Probable cues for spawning are ocean temperature; the number of days/hours of sunlight (cumulative temperature); and/or the presence of a plankton bloom.

Apparently for both Orange Sea Cucumbers and Giant Plumose Anemones, the males are the first to release their gametes, triggering the females to spawn.

Research has also found that, in the case of Orange Sea Cucumbers, females release around 130,000 eggs packaged in buoyant egg pellets. The egg pellets drift to the surface and dissociate into the individual eggs after about 20 minutes. Spawning in orange sea cucumbers most often happens within 1.5 hours after slack low tide which adds to the success by allowing for a greater concentration of sex cells, maximizing the chances of fertilization.

Through these images, I hope I have been able to relay the awe I felt at witnessing this biological marvel that has allowed these species to survive on Earth for thousands of times longer than we humans have walked upright.

Female Gumboot Chiton spawning. Click this link for video and more information.

Giant Plumose Anemones spawning. Males releasing the whiter masses while females’ eggs have a pinkish colour. See the pink egg mass from a female on the right ? ©2017 Jackie Hildering.

Giant plumose anemone releasing gametes. Click to enlarge. © 2014 Jackie Hildering; www.themarinedetective.ca

Male Giant Plumose Anemone spawning. ©2014 Jackie Hildering.

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Super Mom! Up to 300 young under her care.

This is a brooding anemone (Epiactis lisbethae to 8 cm across).

She may not have a backbone but she’s a Super Mom!

As many as 300 young can be clustered around her in up to 5 rows, benefitting from the protective canopy of her tentacles which contain stinging cells (nematocysts). The offspring  remain here until big enough to stand a good chance of surviving on their own. They then crawl toward independence, claiming their own piece of the ocean bottom.

Brooding anemone 1

Brooding anemone with young (Epiactis lisbethae). © 2013 Jackie Hildering. Click to enlarge.

I am awestruck by this species’ beauty and reproductive strategy. It is also a reminder of how little we know about marine species that the brooding anemone was not recognized as a distinct species until fairly recently, and it still so often getting confused with the proliferating anemone (Epiactis prolifera).

I share my marine “detectiving” about this species with you to provide a further example of how extraordinary our marine neighbours are and maybe, thereby, help inspire greater conservation efforts.

But yes, the timing of the blog is no accident. It may be that reflection upon an anemone Super Mom stimulates thought about our human mothers – just in time for Mother’s Day.

So here goes . . . bear with me as I build to clarifying the reproduction of our featured species.

© 2013 Jackie Hildering one time use only-4240156

Anemones have many reproductive strategies.

For many species, reproduction can be asexual as well as sexual with 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!

Some species are hermaphrodites with highly diverse ways by which offspring develop into adults.

In species that have separate sexes, many are broadcast spawners where Mom and Dad release their eggs and sperm into the ocean around them. Fertilization and development thereby happens in the water column.

Then, for only some 20 species of the world’s more than 800 kinds of anemone, there are those in which the female captures the males’ sex cells as they drift by and draws them into her digestive cavity to fertilize her eggs. She “broods’ her young.

Some such anemone species are internal brooders.  The young develop inside Mom until they hatch and are expelled into the water column as planktonic larvae.

But then there’s Super Mom – the brooding anemone (Epiactis lisbethae). She’s an external brooder.

After she has fertilized the eggs inside her digestive cavity with the sperm she has captured, the young develop inside her until they hatch into planktonic larvae. THEN, they swim out of her mouth, settle on her body under the tentacles and grow into little anemones that feed themselves.

When the offspring are big enough to stand a good chance of survival without the protection of Mom’s tentacles, they shuffle away to independence, leaving space for next season’s young.

The brooding anemone’s young are all of the same generation and are therefore all about the same size.

However, there is a second externally brooding anemone species in the eastern North Pacific where you most often see young of different sizes huddled under Mom’s tentacles. This species – the proliferating anemone (Epiactis prolifera) is the one that very, very frequently gets confused with the brooding anemone.

Proliferating anemone.

Proliferating anemone with young (Epiactis prolifera). Often confused with the brooding anemone (Epiactis lisbethae). © 2007 Jackie Hildering. Click to enlarge.

I have strived to clarify the many differences between these two externally brooding anemone species in the table below but to summarize: the proliferating anemone is smaller and does not have striping all the way down the column; adults are hermaphrodites; breeding happens year round; there are far fewer young clustered under mom’s tentacles; and they start off there as fertilized eggs, not as free-swimming larva.

The main similarity between these two species is and yes, I am going to use a tongue twister here since I believe it is inevitable when discussing anemones – with anemone mothers like these, baby anemones are protected from their anemone enemies.

Now off you go, share some ocean love with a Super Mom!

There are so many human females out there worthy of awe. Where, were we to consider how many young they have shielded and helped to independence, the number might well be 300 or more!

 

brooding vs. proliferating table

Click to enlarge. Table summarizing the differences between brooding and proliferating anemones.

 

Brooding anemone with young (Epiactis lisbethae) - all the same age. ©2016 Jackie Hildering.

Brooding anemone with young (Epiactis lisbethae) – all the same age. ©2016 Jackie Hildering.

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