Chances are, you’ve used a sponge recently to clean, scrub or otherwise beautify an area.
While a large amount of the sponges used today are man-made constructs of wood pulp, hemp, polyurethane and other materials, they all take inspiration from a wide group of animals known as poriferans.
These natural sponges are some of the oldest organisms around, and scientists believe sponges took an early evolutionary side road that separates them from most other animals alive today. Sedentary filter feeders, sponges basically form tube-like structures that channel water into themselves at their base and eject the leftovers and waste out of their top.
Similar to loofahs, which come from a type of gourd, natural sponges have been used for centuries in a wide variety of commercial and personal applications. Many Mediterranean and early American cultures relied on abundant populations of sea sponges for trade and industry.
Due to the effects of overfishing, disease and climate change impacts on these ancient animals, the practice of gathering natural sponges is no longer at the meteoric pace it once was. Even in this age of synthetic spongery, natural sponges possess some interesting properties that make them desirable for use by humans.
Like many other aquatic animals, sponges are weird compared to the terrestrial organisms we are most used to seeing. Lacking a nervous system, muscles, organs or even digestive systems, sponges are basically two layers of cells separated from each other by a layer of jelly-like material.
They rely on water currents to supply them with small floating particles, which are then filtered through in search of a meal. Sponges are incredibly effective filterers – they can actually filter particulates as small as bacteria from the water, which are shuttled from the “outer” layer of cells into specialized cells occupying the inner layer.
This is accomplished by delivery cells that live in the middle jelly layer. These middleman cells can also provide some defense to the sponge by constructing mineral deposits from silicon or other ingredients that serve to reinforce the whole, while making it less desirable for predators to munch on.
The vast majority of sponges possess these mineral buttresses, however, a few species have instead developed dense networks of softer fibers woven together in specific patterns. The dried skeletons of these “softer” sponges are the types used by humans for cleaning and absorbing water.
While areas such as the Greek isles were historically known as sponge ground zero, interestingly the world’s current largest natural sponge industry makes its base in Florida, in a town called Tarpon Springs north of Tampa.
Natural sponges are harvested by diving and cutting them, or even by hooking them with a long pole off of a boat. Luckily, sponges are incredibly tough animals that can regenerate themselves from very small pieces left behind after the carnage.
This makes them more resilient to human harvesting than most other life forms. Sponge cells can do more than regenerate from small pieces. Studies have found that the cells in a sponge reorganize themselves depending on the animal’s needs, shuttling between layers and changing their forms in order to pick up the slack when needed.
Sponges can even remodel their entire shape, morphing into whatever mold will most effectively work if local conditions change. While these and other sponge traits allow them to survive and filter to a remarkable degree, they do not work alone. Scientists have discovered that sponges have developed symbiotic relationships with specialized microbes which help them in a variety of ways.
As we learn more about these fascinating bottom-dwellers, perhaps we will be able to utilize some of the unique attributes of natural sponges to better our lives in ways beyond a quick clean.
Brannen Basham and his wife, Jill Jacobs, operate Spriggly’s Beescaping, a business dedicated to the preservation of pollinators. He can be reached at email@example.com.