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Marine Animals in Human Medicine: Will a Sponge Save Your Life?

There are many good reasons to improve ocean health, but one of the most compelling is to make people healthier too.

Beyond providing nutritious seafood and food supplements, marketable products, climate control, employment, recreation and aesthetic enjoyment, marine life has long been used to treat human ailments.  

Traditional medicine in Asia and elsewhere frequently uses marine animals, including dried sponges, corals and jellyfish, shells of crabs, oysters, conch and other mollusks, pearls and cuttlefish ‘bones’, sea cucumbers, sea horses and many other marine animals to prepare powders, ointments and decoctions for many ailments. Their efficacy and method of action is usually not described or tested with western scientific methods even if treatments work as intended. Marine animals used in traditional medicine in India are described here.

In some cases traditional medicine uses large numbers of animals. About 20 million sea horses (about 50 tons) per year are harvested to treat kidney disease, circulatory ailments and impotence with Chinese traditional medicine. Of the approximately 48 seahorse species, 23 are sold as dried specimens for traditional medicine and 30 as live specimens for aquariums. Extensive harvest of seahorses, along with unsustainable by-catch from bottom trawling that indiscriminately kills millions of seahorses annually and disturbs or destroys their habitat, has substantially reduced many populations, but the magnitude of decline is poorly known owing to lack of data: of 38 species included on the IUCN Red List, 1 is Endangered, 10 are Vulnerable to extinction, 26 are Data Deficient and only 1 is at Least Concern for extinction. Seahorse mariculture operations in China, Vietnam, Australia and elsewhere provide live specimens for aquariums, but do not produce dried seahorses, so they will not reduce the pressures on wild seahorse populations.      

 

Here we focus on the ocean’s recent contributions to human health, including newer techniques that can provide medical benefits with little or no harm to marine populations or habitats. The extent of the ocean’s medical chest may surprise you. 

Did you know that sea urchins and starfish first showed us how embryos develop from a single fertilized cell…sharks, skates, lobsters and crabs helped scientists understand how our kidneys work …squids and lobsters built our understanding of how nerves conduct electricity… and horseshoe crabs and skates taught us a lot about human vision?

But serving as models for human physiology was just a start. Now these and other marine animals, plants, fungi and bacteria are contributing directly to curing human disease. The list of chemotherapy agents, antibiotics, anti-virals, anesthetics, adhesives, marine genetic products (MGPs) and others being used or developed to treat cancer, leukemia, cystic fibrosis, heart disease, wounds and infections, among others, includes at least 18,000 products derived from 4,800 species.

Why are there so many? Hundreds of thousands and probably millions of species live in the ocean.  Each has lots of genes that make chemicals basic to life or for more special purposes. Special-use chemicals evolved for defense or aggression, for example to compete for attachment space, prevent overgrowth by encrusting species, deter predators and incapacitate or kill prey; and for communicating information about identity, health and reproductive state to potential mates or others of their own or other species.  These special chemicals are often intriguing to medical explorers, because compounds with one unusual property often have others of biological or medical interest.  

Where are the best places to look for interesting potential drugs? Start in places with high biodiversity, such as coral reefs, coastal mangrove forests, seamounts or other biologically-rich communities. The many species and from which interesting chemicals are likely to emerge. Sedentary animals like sponges, corals, tunicates and others are good places to begin because they are often abundant, easy to harvest, have many species, and protect or defend themselves mainly through chemical means. The numerous symbiotic bacteria living within some of their body cavities can also yield useful chemicals.  Special places with extreme conditions, such as deep-sea thermal vents and arctic regions may also harbor biological surprises, though sampling them is much more difficult and the resulting products may have more applicability for purposes other than human medicine.