Secret life of Plankton

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Secret life of Plankton

Two scientists try to unravel the secrets of the jellyfish’s life cycle.
While one cuts the animals into halves, the other dissolves the whole animals into their single cells.

Have you ever thought about what lives in the water you swim in?

Let’s venture out into the Fjord.

Untangle the net.

The water looks super clear today.
Hope we don’t catch any Jellyfish!

Excited to see what we caught!

The water looks incredibly clear!

Let’s take a look underneath the microscope.

Through the microscope, a previously invisible world is unveiled to us.

Giving us a peek into the

Secret life of Plankton

Through the microscope, a previously invisible world is unveiled to us.

Giving us a peek into the

Secret life of Plankton

Most of plankton is made up of larvae -
the distinct pubescent (juvenile) forms of many sea creatures.

Like we find here!

Secret life of Plankton

Most of plankton is made up of larvae -
the distinct pubescent (juvenile) forms of many sea creatures.

Like we find here!

Hover over the larvae to see their adult forms.
You might be suprised by a few!

How do relatively similar looking plankton
transition in to vastly different adult forms?

Lets take a closer look at the
life cycle of Clytia as it grows into a Jellyfish.

How do relatively similar looking plankton
transition in to vastly different adult forms?

Lets take a closer look at the
life cycle of Clytia as it grows into a Jellyfish.

The larva drifts around in the ocean.

When the conditions are right, the larva attaches to the ground.

...to metamorphose in to a polyp that will give rise to a colony.

Eventually, some of the polyps bud off baby jellyfish

...that grow into mature jellyfish.

Metamorphosis

It’s incredible, almost unbelievable, how the jellyfish larva and other plankton can transform in to vastly different body forms, just like Kafka’s Metamorphosis.

Metamorphosis

It’s incredible, almost unbelievable, how the jellyfish larva and other plankton can transform in to vastly different body forms, just like Kafka’s Metamorphosis.


It’s a fascinating topic and scientists
around the world are trying to uncover
its secrets.

Metamorphosis

It’s incredible, almost unbelievable, how the jellyfish larva and other plankton can transform in to vastly different body forms, just like Kafka’s Metamorphosis.

It’s a fascinating topic and scientists
around the world are trying to uncover
its secrets.


Depending on the questions you ask,
there can be numerous different ways
to search for an answer.

Anna and Julia

Our researchers from the Villefranche-sur-Mer Marine Station are trying to uncover some of the secrets of this Jellyfish, Clytia Hemisphaerica.


They each use different approaches in their research process. Julia cuts the animals into halves, while Anna dissolves the whole animal into its single cells.

Anna and Julia

Our researchers from the Villefranche-sur-Mer Marine Station are trying to uncover some of the secrets of this Jellyfish, Clytia hemisphaerica.


They each use different approaches in their research process. Julia cuts the animals into halves, while Anna dissolves the whole animal into its single cells.

The settlement

Julia is interested in the transition from the larva stage to the adult polyp.


It is a key process in allowing species to colonise new ecosystems.


The larva fixes onto a surface, which could be a rock, algae, the sea bed... choosing a suitable environment

The settlement

Julia is interested in the transition from the larva stage to the adult polyp.


It is a key process in allowing species to colonise new ecosystems.


The larva fixes onto a surface, which could be a rock, algae, the sea bed... choosing a suitable environment

The settlement

Julia is interested in the transition from the larva stage to the adult polyp.

It is a key process in allowing species to colonise new ecosystems.


The larva fixes onto a surface, which could be a rock, algae, the sea bed... choosing a suitable environment

Julia wants to understand how the larva senses and responds to external cues to find the best place to settle.

We know that larvae fix to the substrate through the front end of the body.

We also know that the nervous system of
the larva is concentrated here.

We know that larvae fix to the substrate through the front end of the body.

We also know that the nervous system of
the larva is concentrated here.

This is why Julia cuts the larva in two halves
(the anterior & the posterior) to then compare their cellular and molecular composition.

This is why Julia cuts the larva in two halves
(the anterior & the posterior) to then compare their cellular and molecular composition.


To understand this process better, she then looks for specific cells and genes in the front half of the larva that are key in the settlement.

Cutting animals in halves

While Julia applies this traditional technique of cutting the animal into halves to answer her question,

Anna asks a different question and therefore follows a different and new technique.

Adult and Larva

Anna is interested in the differences between the adult jellyfish and the larva.

We have two completely different looking body forms during one animal’s life, but there might be more similarities when we take a look at the cells that make them up.

Anna is asking: Do the adult and
larva share similar types of cells?

For this she dissolves the whole larva and
adult animal into their thousands of individual
single cells, by immersing the animals into a
modified artificial sea water without calcium and magnesium.

She then filters the cell suspension.

She now needs to identify, group and compare the individual cells.

This is done on a molecular level.

Real image of single cell suspension

Techniques

This approach is very new and has only been established in recent years. We can actually compare individual cells across the broad range of different species and their life stages!

Techniques

This approach is very new and has only been established in recent years. We can actually compare individual cells across the broad range of different species and their life stages!


In comparison, the traditional technique of "cutting animals into halves" is used to understand the mechanistic rules of development within an animal.

While Anna and Julia are trying to uncover the secrets of a single living species, we can also take a look at the bigger picture again and at questions that arise if we think about their evolution.

Why are larvae of marine animals so similar to
each other when the adults are so different?

Why are larvae of marine animals so similar to
each other when the adults are so different?


Is it because the last ancestor of these animals already had a larva and these evolved much more slowly than the adult forms?

Why are larvae of marine animals so similar to
each other when the adults are so different?

Is it because the last ancestor of these animals already had a larva and these evolved much more slowly than the adult forms?


Or are the similar-looking features of these larvae so well suited for living in the sea that different animals re-invented them over and over again in the same way?

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