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James Dawson
James Dawson
Introduction
Introduction
Can animals use photosynthesis for their primary feeding? If you answered no there is no way that can happen, nope there is an exception just like every other rule in science! There is the Emerald green sea slug which can use photosynthesis to feed. This awesome slug has the ability to produce its very own chlorophyll which is the pigment found in almost all plants. Not only can it do this, but it has the appearance of a leaf with a snail head in the shallow salt marches of the North American Atlantic coast. These amazing creatures have a life span of 9 to 10 months. In this time, they can grow anywhere between 1-6 cm (Rafferty, 2020).
It is believed the photosynthetic ability come from eating a yellow-green alga called Vaucheria litorea. The genes from this alga is incorporated in the slug’s DNA but is not used. The slug can survive in extreme darkness, so this means they are consuming nutrients from other sources (Rafferty, 2020).
Retrieved from: https://www.nature.com/articles/sdata201922
Image showing metamorphosis
Image showing metamorphosis
Image shows the metamorphosis of slug from formation to young to inclusion of chloroplasts to adult form.
Retrieved from: https://www.pnas.org/content/105/46/17867
Taxonomy
Taxonomy
Common Name: Emerald Green Sea Slug or Eastern Emerald Elysia
Scientific Name: Elysia chlorotica
Taxonomic classification hierarchy. (As you progress through the hierarchy of the classification you get more and more specific until the species is reached.) This is in the genus of Elysia which included most of all of the sea slugs.
Kingdom: Animalia
Subkingdom: Bilateria
Infrakingdom: Protostomia
Superphylum: Lophozoa
Phylum: Mollusca
Class: Gastropoda
Subclass: Opisthobranchia
Order: Sacoglossa
Family: Elysiidae
Genus: Elysia
Species: Elysia chlorotica
From: (ITIS)Niche and Habitat
Niche and Habitat
This emerald sea slug is found across the east coast of North America in the Atlantic Ocean. They are found as far south as Florida and as far north as Nova Scotia, Canada. They can be found in salt and tidal marshes, and shallow creeks or pools. They are also known to have the highest survivability in salt of any other organism. They can survive waters as high as 24 mosm levels of salt. They are always found close to their food source which is the Vaucheria litorea which is a yellow-green alga. This relationship is known as a obligate relationship where the slug relies on the alga to survive. This source is so important because not only does it supply nutrients but impacts physical development (Blanchet, 2012).
Dots show hot spots for the emerald green sea slug
Retrieved from: https://www.discoverlife.org/mp/20q?search=Elysia+chloroticaEvolutionary History
Evolutionary History
As in the pictures this slug looks like it is a leaf. How did this slug evolve to not only look like this but use photosynthesis as a source of food? This happens before the slug matures. The slug ingests algae in its larval stage. This is where the chloroplasts become a part of the slug. The slugs will turn a green color because the chlorophyll pigment is expressed. That is why the appearance of a leaf is formed so the slug can maximize the amount of sunlight it picks up (Encyclopedia of the Environment).
Most of the time in other animals these chloroplasts would be digested but not in this slug. The chloroplasts are not broken down but become a major part of the slug’s body system. For photosynthesis to work the slug’s genetics are changed. This is accomplished by a horizontal gene transfer between the algae nucleus and the nucleus of the slug (Rafferty, 2020).
Picture shows the leaf like body of the slug
Retrieved from: https://www.encyclopedie-environnement.org/en/zoom/elysia-chlorotica-the-slug-who-thinks-shes-a-leaf/Environmental Impacts
Environmental Impacts
These slugs have hardly any impact on the environment because of how they feed. Since they only eat the algae V. litorea and do not consume anything else there is not any kind of possible problems they can cause (Blanchet, 2012). The use of sunlight as their main source of nutrients also means they can take in CO2 (Encyclopedia of the Environment).
Shows the sea slug with algae
Retrieved from: https://mymodernmet.com/elysia-chlorotica-solar-powered-sea-slug/Conservation
Conservation
It is very hard to find these slugs, but they are not on any lists for conservation. The only concern is the loss of their habitat. Since they live in salty marsh on the east coast there is a chance of development taking their natural homes. These are very strong animals and can survive well (Blanchet, 2012).
They have not shown any current benefits to humans, but they are very interesting for scientists to study. They have many components before they eat the alga. This is something not currently understood as to why this animal is able to do this (Blanchet, 2012). This slug is not showing any signs of disappearing, but they do need to like all other organisms looked after.
Image illustrates the slug floating along with the algae
Retrieved from: https://en.wikipedia.org/wiki/Elysia_chloroticaFriends or Foes?
Friends or Foes?
These slugs mainly just coexist with V. litorea. This alga is very important to develop these slugs so if this alga disappears so do the slugs. They have to feed on it before they can go through metamorphosis. Once the slug becomes an adult it still relies on V. litorea to collect nutrients from the chloroplasts. Once the slug digests these nutrients, they turn the green color and can be photosynthetic for up to 10 months (Blanchet, 2012).
There are absolutely not any predators that these slugs have to worry about currently. They can blend in with the vegetation due to their green- leaf like body (Blanchet, 2012). This makes it to where they do not have to worry about being eaten.
A enhanced view of V. litorea
Retrieved from: http://www.seaslugforum.net/find/1969Videos to watch
Videos to watch
Web Resources for Audience to Explore
Web Resources for Audience to Explore
This web site can give a introduction to photosynthesis: https://www.livescience.com/51720-photosynthesis.html
This web site can show other cool sea slugs: https://www.boredpanda.com/sea-slugs/?utm_source=google&utm_medium=organic&utm_campaign=organic
This web site gives some additional information on Vaucheria litorea: https://www.algaebase.org/search/species/detail/?species_id=522
This web site gives some additional information on the gene transfer used by Elysia chlorotica: https://www.newscientist.com/article/dn16124-solar-powered-sea-slug-harnesses-stolen-plant-genes/
This web site shows 2 additional animals that use photosynthesis: https://futurism.com/photosynthetic-animals
Resources
Resources
Blanchet, C. (2012). Elysia chlorotica. Animal Diversity Web. Retrieved on June 11, 2020, from https://animaldiversity.org/accounts
Encyclopedia of the Environment. (N.D.). Elysia chlorotica, the slug that behave like a leaf. Retrieved on June 11, 2020, from
ITIS. (N.D.) Elysia chlorotica. Retrieved on June 11, 2020, from https://www.itis.gov/servlet/SingleRpt/SingleRpt?search_topic=TSN&
Rafferty, J. P. (2020, June 6). Elysia chlorotica. Britannica. Retrieved on June 11, 2020, from https://www.britannica.com/animal
When applicable add your google docs lesson plan here.
When applicable add your google docs lesson plan here.
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