Elegant anemone-Clone of my own

by Matthew Norton

In the natural world, creating the next generation is a complicated process with multiple ways for animals to reproduce. The coming together of a male and female to create new life (sexual reproduction) provides each of their offspring with a unique mix of their genes. This helps to keep the variety of genes in the species high, which in turn creates a high variety in all the features that genes control (e.g. body size, eye colour) and gives evolution more options to work with. However, there are some species that use the older method of producing exact copies of themselves (asexual reproduction).

Elegant anemones, Sargatia elegans (not to be confused with Actinoporus elegans), produce their identical clones from bits of their body that break off as they crawl along the seabed. This can allow elegant anemones to rapidly take over sections of the seabed with sheer numbers. They are also well equipped to defend their territories, using their long stinging tentacles to drive away corals, sponges and other anemones. However, this is not a perfect defence and some bacteria are able to slip through the net and live in elegant anemones’ tentacles.

Elegant anemone blog article image 1
Elegant anemones stand out with their banded colour pattern and the jagged outline on their base (not visible here) which is a tell-tale sign of their reproduction through fragmentation.

Of course, there are drawbacks to how elegant anemones reproduce. For example, they do not release their young into the water to be carried away by the currents (as is the case with many other marine species), which can make it difficult for elegant anemones to disperse into new areas. Also, because they rely on producing identical clones, elegant anemone populations may struggle to adapt to changes in their environment because evolution have fewer sets of genes to work with. For example, elegant anemones have been wiped out from some areas of the seabed around the Netherlands following a severe winter.

Surprisingly, elegant anemones have managed to overcome their limitations and distribute themselves over large areas of the world’s oceans with reports in 2013 of their spread into the Black Sea. Also, their populations seem to have surprisingly high variety of genes, which suggests that each population was founded by multiple anemones with different genes. In theory, this is possible if these founding anemones came from different populations that were separated from each other and allowed to develop different sets of genes over time before being brought together at a later date.

There is a common misconception that creatures with simple features, such as asexual reproduction, are in some way less evolved. However, the truth is that evolution only provides each species with the upgrades that they need, and not every species needs to be so complicated. It is also worth mentioning that even without sexual reproduction, there are various ways that an animal’s genes and physical features can change over time and give evolution the tools it needs.

From a human perspective

A lot of sea creatures have evolved weapons for attacking prey and defending themselves from predators and unfortunately we can sometimes get caught in the crossfire. In the case of elegant anemones, and other Sargatia anemones, their tentacles are loaded with special stinging cells called nematocysts.

Elegant anemone blog article image 2
All cnidarians (e.g. jellyfish, anemones, corals) have these microscopic harpoons tipped with toxins that can produce a nasty sting.

These stings are a particular danger to fishermen who collect the sponges that live among Sargatia anemones and may then suffer from sponge fishermen’s disease, also known as Sargatia’s dermatitis. This condition can include some nasty symptoms, such as burning/itching sensations, redness of the skins and blisters, which can then develop into ulcers and abscesses. In more extreme cases victims suffer from nausea, vomiting, fever and muscle spasms.

Elegant anemone blog article image 3
Portraits of sponge fishing seem to date back to at least the 19th century which probably means there have been sufferers of sponge fishermen’s disease since then.

Apart from their stings, elegant anemones do not appear to have any other connections with our lives. However, I would like to suggest some ideas on how these anemones may still be useful to us, especially in scientific research. For example, their strange way of reproduction may make them a species of interest for genetic research (the study of genes), particularly in how genes change over time without sexual reproduction. This idea was explored (sort of) in a 1929 experiment where several anemones, including elegant anemones, were studied to compare their very different ways of reproducing, although genetic research was a very new science back then.

Elegant anemone blog article image 4
The 1929 study on several sea anemones included species that can reproduce through cutting off fragments from their base (left), species that are hermaphrodites (both male and female) and practice sexual reproduction (middle) and species where new anemones stretch out from their parents and then snap off (right).

Their ability to easily produce identical clones of themselves could also make useful ‘lab rats’ for all kinds of laboratory experiments. Especially, because this (almost) removes a common source of confusion with the results of these experiments, the difference in genes among the test animals. However, we do need to be careful because genetic differences between animals are an important part of the natural world and without them the results of these experiments may not be that useful.

There are also practical reasons why elegant anemones are useful test animals to keep in a laboratory, despite their stinging tentacles. It is easy to get lots of them to work with by collecting the fragments from a few wild caught anemones and, being quite simple animals, all you only really need to provide them with food and the right living conditions in a small water tank. Also, because of their limited ability to disperse into new areas, elegant anemones are unlikely to escape from the laboratory and invade new areas of the seabed, although such escapes should still be prevented where possible. Not only would these potential invaders be stuck to one area, but they would likely struggle to adapt to their new surroundings. There are even records of an elegant anemone invasion in Massachusetts in 2000 eventually failing by the end of the decade.

In this article I have included some ifs, buts and a lot of blue sky thinking with not much evidence to back it all up. In all honesty, the nasty effects of elegant anemone stings was all I really had and I didn’t have much luck in finding particular incidents to talk about. However, I think it is always worth imagining how else the creatures of the sea might affect our lives, especially as there is so much of their world that we know nothing about.

Elegant anemone blog article image 5
Thanks for reading

Sources

Wikipedia. 2018a. Sargatia elegans. https://en.wikipedia.org/wiki/Sagartia_elegans. Last accessed 09/06/2019

Wikipedia. 2018b. Elegant anemone. https://en.wikipedia.org/wiki/Elegant_anemone. Last accessed 09/06/2019

Marine Species Identification Portal. Sagartia elegans. http://species-identification.org/species.php?species_group=anthozoa&id=80. Last accessed 09/06/2019

Schuett and Doepke. 2009. Endobiotic bacteria and their pathogenic potential in cnidarian tentacles

Ates et al. 1998. The occurrence of Sagartia elegans (Dalyell, 1848)(Anthozoa: Actiniaria) in the Netherlands

Shaw. 1991. Effects of asexual reproduction on population structure of Sagartia elegans (Anthozoa: Actiniaria)

Bengtsson. 2003. Genetic variation in organisms with sexual and asexual reproduction

Grebelnyi and Kovtun. 2013. A species of sea anemone Sagartia elegans (Dalyell, 1848) (Anthozoa, Actiniaria, Sagartiidae) that is new for the Black Sea and is capable of clonal reproduction

Bonamonte et al. 2016. Aquatic Dermatology: Biotic, Chemical and Physical Agents

Elston. 2007. Aquatic antagonists: Sponge dermatitis

Wells. 2013. The failed introduction of the sea anemone Sagartia elegans in Salem Harbor, Massachusetts

Stephenson. 1929. On methods of reproduction as specific characters

Image sources

gordon.milligan. 2014 [CC BY 2.0 (https://creativecommons.org/licenses/by/2.0)%5D. https://commons.wikimedia.org/wiki/File:Sagartia_elegans.jpg

Mike Noren. 2001 [CC BY-SA 3.0 (https://creativecommons.org/licenses/by-sa/3.0)%5D. https://commons.wikimedia.org/wiki/File:Diadumene_cincta_DSCN1979.JPG

Ecomare/Sytske Dijksen. 2016 [CC BY-SA 4.0 (https://creativecommons.org/licenses/by-sa/4.0)%5D. https://commons.wikimedia.org/wiki/File:Ecomare_-_slibanemoon_(pcd02025-slibanemoon-sd).jpg

Fernándo Herranz Martín. 2005 [GPL (http://www.gnu.org/licenses/gpl.html)%5D. https://commons.wikimedia.org/wiki/File:Actinia_pedunculada_014.jpg

Mike Noren. 2001 [CC BY-SA 3.0 (https://creativecommons.org/licenses/by-sa/3.0)%5D. https://commons.wikimedia.org/wiki/File:Sagartiogeton_laceratus_DSCN2001.JPG

Learning by action; Stichting Natuurbeelden. 2010 [CC BY-SA 3.0 nl (https://creativecommons.org/licenses/by-sa/3.0/nl/deed.en)%5D. https://commons.wikimedia.org/wiki/File:Actinothoe_sphyrodeta_in_the_Netherlands.jpg

All other images are public domain and do not require attribution

 

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