Underwater creatures with regeneration ability (Part 1)

Underwater creatures with regeneration ability (Part 1)

Have you ever heard of underwater creatures with regenerative abilities? It is the same as tissue, organs, body parts lost or damaged by a cut, disease, or aging of the body parts are being repaired, left to be repaired and grow a new one!

Now let us introduce you to some underwater creatures with special regeneration functions! you may not really know! It’s really exciting!

Octopus

Regeneration of the octopus is more advanced
Photo credit: Morten Brekkevold

Octopuses can break their arms (tentacles) to survive when in danger. We’ve all heard that lizards can regenerate their tails, but regrown tails aren’t as good as the original tails in shape and function.

The regeneration of the octopuses is more advanced and they grow again. Its arms and legs can be as perfect as the original ones.

When the arm breaks, the regeneration process begins. The first is to narrow and close the blood vessels in the injured area by itself to prevent bleeding.

After 6 hours, the blood vessels start to circulate and the blood gradually circulates through the injured tissues. The solid clot covers unhealed wounds on the arms and limb.

Acetylcholinesterase (AChE) plays the most important role in activating repair during this process.

This enzyme is also present in human brain neurons. It is especially active in the repairing octopus arm.

The wound can heal completely the next day and a new arm will grow to one-third of the original length after one and a half months.

Sea cucumber

regenerative ability of sea cucumber is also stronger
Photo credit: Dawid Kalisinski

The sea cucumber is an echinoderm that has survived for over 600 million years.

Although this is a low-level animal with almost no attack ability, it can survive multiple extinctions. Sea cucumbers can thrive in such a family.

First, they cannot do without their super reproductive capacity. An adult sea cucumber can lay 5 million eggs at a time.

As long as a survival rate of one in ten thousand can ensure the prosperity of the offspring. The regenerative ability of low-level animals such as sea cucumbers is stronger.

Unlike higher creatures who can only heal wounds, sea cucumbers have incredible ability.

When sea cucumber is attacked from outside the marine environment becomes worse, it should expel their own organs from the chrysanthemum.

The internal organs (the sea cucumber that loses internal organs will not die), first feed the enemy a full meal and save a sea cucumber’s life. A whole set of internal organs can be regenerate in about 30-50 days.

Starfish

The regeneration and repairing ability of the starfish is familiar to us
Photo credit: Tijana Mihajlovic

The regenerative and repairing ability of the starfish should be familiar to us. If a wrist is broken, a new one can grow.

Some starfish must have a central disk (the central part of the body) to regenerate other wrists, and some Starfish can only use one wrist to give birth to a whole starfish.

This powerful regeneration ability comes from the scattered nervous system and stem cells of the starfish.

The body of the starfish is radially symmetrical. Most of the important organs are found in the wrist. The nervous system is also distributed throughout the body.

When some limbs are injured, they will not die immediately. Stem cells in the body are activated and can differentiate with any need for regeneration. The cells help regenerate the damaged part.

Conch

The closeup Picture of Conch from Sharon Channel
Photo credit: Sharon Channel

The conch has more visual abilities than other gastropods. The queen conch in the picture above has a pair of stalked eyes.

Compared with other gastropods, their eyes are very large, with a diameter of 1.5mm and complex.

The principle of optical imaging. Unlike the regeneration of broken hands and feet, this type of conch can grow new long eyestalks within a few weeks.

It is necessary to know that the structure and fineness of the eyes are much more complicated than the hands and feet, and they need to be composed of visual organs.

Highly specialized cells and complex neural networks work together to complete vision.

Regeneration process of eye stalks of Conch with in 8 weeks appears in this figure
Photo credit: Jamie Clark

Jellyfish

Jelly fish also have a different  regenerative strategy
Photo credit: Peter Neumann

Jellyfish can not only heal and regenerate damaged bodies like the several marine creatures mentioned above but when the tentacles are cut, they are not just as simple as regenerate tentacles, they have a completely different regenerative strategy: sea moon jellyfish The two tentacles of (Aurelia aurita) have been cut off.

Instead of directly regenerating new tentacles, it rearranged the remaining six tentacles to adjust the muscles to maintain its own balance. This process is also called “symmetrization”.

Regeneration of jellyfish tentacles by adjusting the muscles to maintain its own balance
The picture is from Abrams et al.

The life of a jellyfish begins with a jellyfish larva, drifting in the ocean, looking for a suitable surface to stop, develops into a polyp, and then develops into the second stage of the jellyfish life, the jellyfish body can also “resurrect from the dead”.

When the body of the flagship jellyfish (Turritopsis nutricula) dies, its cells will reassemble and restart the life cycle of the jellyfish, forming the first stage of the hydra, and then developing into a new jellyfish.

Lobster

The lobster mentioned here refers to the lobster family (Nephropidae). For example, the Boston lobster has two large lobsters, and they can live to be over 100 years.

Spiny Lobsters, like Aolong (Australian lobster), have thick tentacles and spines, and their lifespan is only around 20 years.

The secret to lobster longevity is hidden in their genes. Under normal circumstances, human cells continue to divide and replicate throughout their life, but most cells can only replicate about 50 times before reaching their limit and starting to age and to die.

Spiny lobsters have thick tentacles and spines
Photo credit: Wen Panda

This limit is determined by the telomeres (telomeres) at the ends of chromosomes in the cell.

Each time a cell divides, this telomere shortens until the chromosomes cannot be protected, so the cell dies.

Almost all animals comply with this rule. But the situation with lobsters is completely different.

They can produce enough telomerase, which can restore the length of telomeres and maintain the ability of cell proliferation.

In theory, lobsters seem to grow indefinitely and live forever. However, the impact of the actual living environment, the invasion of viruses and bacteria, and the fishing of humans have prevented them from achieving immortality.

Moreover, the main reason why they can’t grow indefinitely is also the death caused by being oversized. Lobsters have exoskeletons. Every time they grow, they need to go through the process of shelling.

The bigger lobsters grow, the more energy they need to replace. Shell, many lobsters eventually die from energy exhaustion, incomplete shell replacement, inability to resist predators during shell replacement, and so on.

Conclusion

Creatures with regenerative ability in the ocean are not just the ones above, in the next article, We will continue to introduce you to more amazing marine organisms with regenerative ability!

Related article

How Octopus Arms Regenerate with Ease

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Deep Diving Exploration Under Antarctica: a shocking world

References

Okada, A., Kondo, M. Regeneration of the digestive tract of an anterior-eviscerating sea cucumber, Eupentacta quinquesemita, and the involvement of mesenchymal-epithelial transition in digestive tube formation. Zoological Lett 5, 21 (2019).

Clark, J. M. (2018). Restoration of visual performance and opsin expression within the retina during eye regeneration in the Florida fighting conch (Strombus alatus).

Disclaimer

Some photos of the article are from the Internet. If you have any copyright issues, please contact us.

Rajitha Dissanayake

Researcher in the field of Marine Mammals and Bio-acoustic

I'm a Master’s student in marine mammals and bio-acoustic laboratory, Institute of Deep-Sea Science and Engineering (IDSSE), Chinese Academy of Sciences (CAS) and focusing on the sustainable environmental application, conservation, and exploring all aspects of the ecology and behavior of marine mammals.

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