Do Sponges Protect Themselves? – In More Ways Than One

All animals and plants (all life in fact) faces different threats to their survival. Sea sponges, however, have more experience in survival than any other animal that has ever existed. We all can take a lesson from these exceptional survivors.

You may ask, How do sponges protect themselves? Well, they don’t run or fight back in the usual sense. In fact, they are sessile – that means they spend their entire lives in one spot. If they move at all, it is done at a cellular level.

That is too slow to be captured by the human eye or any eye for that matter. You don’t want to wait around for a sponge to move.

Just because sea sponges don’t move does not mean they are defenseless. These survivors have evolved some exceptionally effective defensive strategies. It’s because of this that they continue to survive and thrive after 600 million years.

When an animal can’t run or hide then you have to stand your ground and give yourself the best chance to come out alive. One way the sponge does this is by making itself a pain to eat.

They may be few in numbers, but some animals have ability to consume the sea sponge. Even then the sponge still has one more way to cheat death.

Take It Easy Man.

Being the first animal to appear on Earth, the sea sponge had to also be the first to cope with a dangerous and threatening environment. It did not, however, evolved muscles to move or even a nervous system to command any muscles at all. In fact, the sea sponge did not concern itself with growing any organs whatsoever.

The matter of do sponges protect themselves or not was squarely on the time table. It was the future of animals, after all, that depended on the survival of this evolutionary pioneer.

Technically, sponges can and do move. Their movement is done at a cellular level, however.

Our own bodies are made of cells, and they move – they have to in fact.

Well, the sea sponge moves in a similar fashion he; their cells protrude and retract with the help of micro tubules found inside their cells. These structures will determine the shape of the sponge cell, which in turn will in turn dictate the direction of movement.

In fact, in the year 1988, a couple of researchers (Albert and Bond Harris) described that the cells that make up the outermost layer of a sponge (pinacocytes) were working together to crawl. This crawling allows the entire sponge to move (Newscientist).

I’m sure this movement has its purpose; however, its hard to see how it can help the sponge escape any predators. Just to give you an idea how slow this motion is – grass grows significantly faster that a sponge moves. I assume you won’t want to hang around to see a sponge move about.

One Way or Another

If you can’t flee fast enough to escape danger, then you have to stand your ground. This is exactly what the sea sponge has been counting on for survival for the entirety of its existence on earth.

Our resourceful sponge has evolved two main approaches to defend itself against predators and adversaries alike.

Their bodies are supported by a skeleton which is made up of structures called spicules. These, besides supporting the body of the sponge, offer protection as well. They simply make the sponge difficult and painful to chew and swallow.

Have you ever tried to eat a fish that’s full of spines? If you have, then you have at least some idea how it feels to eat a sea sponge. Well, imagine that with a toxic taste to go with it – not exactly a pleasant experience.

To avoid having a potential predator from coming close enough to cause any harm, the sea sponge resorts to chemical warfare. Bacteria that live within the sponge, compensates its host be making some powerful chemical cocktails that taste awful. Those that have tried before are well aware of the awful taste, while those that are new to the game will quickly find out.

Besides protecting themselves from being eaten, sponges have to contend with other creatures in the coral reef (including other sponges) for space. By releasing powerful chemicals the sea sponge ensures that other creatures competing for space in the reef will stay as far away as possible.

Using chemicals for defense has evolved to include both present day animals and plants (Wikipedia). It’s fascinating to have with us today the first creature that invented this defensive strategy that’s widely used today by a great number of plants and animals. It’s clear that the “blueprints” of life were drawn within the sea sponge hundreds of eons ago.

Few In Numbers

The tough sea sponge does a great job at keeping itself off the menu of most animals. Nevertheless, there are a few animals that manage to have a palate for this tough to swallow creature. Known as Spongivores, these few animals are especially adapted to make sea sponges a main part of their diet (Wikipedia). These animals’ anatomy and physiology have evolved in order to consume the impalatable sea sponge.

One of the few animals depends on the sea sponge as the main part of its diet is the hawkbill turtle. In fact, it is the only reptile in the world that consumes sponges. For example, ninety-five percent of the Caribbean hawkbill turtle’s diet is made up of different species of turtles. There must be something special about this animal to be able to tolerate the sponges tough defenses.

The few spongivourous fish are the emperor angelfish, the filefish, and the spotted trunkfish.

In addition, some species of nudibranchs, which are a type of soft-body marine molluscs, It’s a good thing that the sea sponge has relatively few predators. Sponges play a crucial role in the formation and maintenance of coral reefs.

These include keeping the growth of the coral in balance, by turning limestone into fine sand known as bioerosion. They also provide, otherwise inaccessible, nitrogen to other members of the reef. Nitrogen levels are usually in low levels around coral reefs. The little that is found is inaccessible by virtue of being dissolved in organic matter or bound to particulate. Furthermore, the water in which the sponges happen to live is exceptionally clean. This is because these creatures filter a tremendous amount of water each day. So much so that sea sponges are extremely difficult, if not impossible to keep in a tank.

It is clear as sea water that sea sponges are a critical link of the worlds’s coral reefs. Having few predators assures that the level of their contribution to the reefs and our oceans is maintained.

Sea sponges don’t appear as if their population needs to be kept in check by a great number of predators. Remember that they were the first animal to be introduced to our planet. That means that their predators evolved long after and they turned out to be few in numbers. This allowed the sea sponge to populate our oceans. In doing so, they provided pristine water and important nutrients to many of the coral reef’s inhabitants

Give Me A Break

Even when the sea sponge becomes a meal for one of its few predators, this great survivor has one more way to cheat death.

Sponges have more than one way to procreate; they can do so either sexually or asexually. The latter gives them an edge when parts of them are being bitten off by a hungry predator.

As the attacker tries to break off a piece of sponge, some pieces will fall to other parts of the reef where they will regenerate to become exact copies of the adult. The fact of the matter is that the new sponge will grow to be even more robust than the original.

The sea sponges’ natural defenses and its power to regenerate give it a superb edge in the fight to survive. Knowing this gives a renewed appreciation for this amazing life form and what has greatly contributed to its phenomenal success.

Defense Over Offense

The sea sponge has come an incredible long way without rushing. In fact, you have a better chance of seeing grass grow than see a sponge move. That ‘s because they move at a microscopic level – that is, they use their own cells to move.

This requires them to have a robust defense mechanism in order to have the best chance of survival in the face of various threats. As a matte of fact, the sea sponge have evolved a number of strategies to handle potential predators and would be invaders of their space – including other sponges.

Their skeletons are made up of structure known as spicules. These make the sponge painful to swallow. To avoid a predator or invader from coming close in the first place the sea sponge releases powerful toxins. For this reason they have few predators, including the Hawkbill turtle and the Emperor angelfish.

If the predator manages to overcome the sponge’s defenses and actually bites off a piece, then all is not lost for our sponge. Thanks to the sea sponge’s ability to regenerate, any pieces that happen to fall will grow to be a new sponge.

By now, we have a better idea how sea sponges have been able to overcome dangers throughout the eons. They deserve our respect and our commitment to preserve their only home – the ocea




What do you think of the sea sponges amazing defenses? Do you think the world stood to benefit for the sponges’ relatively few predators?



Do you have a favorite animal that uses defense over offense?



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  1. It looks like the sea sponge has several things that are going for it, namely a very bony texture with a toxic taste that no animal wants to eat. It also blends in with the environment so often you can not tell between it and coral. Are sea sponges fish or how do they differ from fish?

    • Hey Jon! Sea sponges are so much more than many of us imagine. When we do think of sponges, it’s usually for bathing or washing. But the natural sponges come from sea sponges, who are awesome creatures. They are the foundation of coral reefs and have existed longer than any other multi – cellular life form in the history of earth. 

      They are well protected by (like you said) a tough and prickly skeleton and powerful chemical toxins that repel would be invaders and predators. 

      Sea sponges are not fish – they have no organs at all – only specialized cells with special functions. These cells can exist independently and work together with similar cells. 

      Sea sponges are the link between single -celled organisms and multi – cellular creatures such as ourselves, 

      Thank you for your comment, 


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