Today, let’s dive into the topic of sponges.
Natural sponges are sessile (immobile) marine invertebrates of the animal phylum Porifera (pore-bearing). They lack complex nervous, digestive, and circulatory systems but rely on constant water flow through their bodies to take in nutrients and oxygen, and to remove waste. There are nearly ten thousand known species; some feed on planktonic bacteria; others host symbiotic organisms to thrive, and some have even developed predatory survival strategies in nutrient-poor environments.
Natural sponges have been used by humans for thousands of years; archaeological excavations have found evidence of sponges used to plaster and paint the queen’s walls at Knossos (the Minoan culture of Crete, c. 1700 to 1400 BC). They have been found on Greek pottery from around 760 BC in depictions of thermal scenes or as status symbols. Oppianus Cilicius (2nd C BC) was the first to write about those fishing for sponges, including details about the spongers’ lifestyles and diets, and the dangers they faced from shark attacks (for an interesting video on the topic of modern spongers, click here). Aristotle (384–322 BC) described the “elephant nose-like tube” used by the sponge divers to breathe. In the Iliad and Odyssey, Homer makes reference to sponges as hygienic utensils. Pliny the Elder (AD 23-79), among others, described the uses of sponges in agriculture and cooking. Cicero (106-43 BC) referred to their use in washing or cleaning. Roman legionaries were supplied with sponges to stuff into their helmets, for personal hygiene, and for drinking (their ancient solution to a water bottle); let’s hope that those were three different sponges allotted. This explains the presence of a sponge at the cross in Matthew 27:48/Mark 15:36/John 19:29.
The first use of a sponge with inhaled surgical anaesthesia is recorded in AD 1025 by the Persian physician Ibn Sina, who used a concoction of potent (=poisonous) sedatives of opium, mandrake and hemlock. Medieval European physicians sometimes used crude herbal mixtures or opium sponges to administer a type of anaesthetic, but it was a far cry from what we know today; at best, it got the patient drunk or high enough not to scream as loudly. Ether vapour as an anaesthetic didn’t make its way into use in Europe until 1846, at the London University College’s theatre.
By the mid-twentieth century, overfishing brought both the sponges and the industry close to extinction. Overharvesting strained the sponge populations around the Mediterranean and the Caribbean; other stresses include storms (which can suffocate them with sand and debris, or rip them loose from their anchors) and climate change (disease outbreaks occur more frequently in warming ocean temperatures). The depleted population also puts stress on the entire environmental chain: Sponge feeders, such as parrotfish or angelfish, move on; without their presence, rapid-growing sponge species smother reef-building corals, which in turn reduces breeding, hiding, and feeding places for other marine species. Changes in harvesting policies and practices in some regions may mitigate these issues: By cutting the sponges loose rather than ripping them out, sponges have a chance to regenerate. But as more people in the First World become concerned with using natural products, marine sponges will continue to be (over-)harvested.
Sponges today are usually synthetic, invented in 1937 by the German scientist Otto Bayer, who (in the good ol’ fashioned way a lot of discoveries have been made) accidentally created polyurethane foam. By the 1940s, the DuPont company had begun mass-producing sponges made from wood pulp, hemp fibres, and sodium sulphate. By the late 1950s, dual-purpose sponges were introduced.
An alternative to both the marine- and synthetic sponges is the Loofah (Luffa) gourd: Besides being a food in the earlier stages of its cycle, when these gourds are left on the vine to dry out, they become a fibrous, natural sponge. For a short video on how to harvest and use a luffa gourd sponge, just click here. If I had a garden, I would certainly try to grow these!
What kinds of sponges do you have in your home? I hope this helps you appreciate the humble sponge, whichever form you use.
Stephanie Huesler 