August 30, 2013
You’re at the beach for a weekend with family or friends. Splashing and jumping, dunking your head beneath the waves, you start to cool off. Then you feel something soft brush against your leg—and suddenly, the coolness is replaced by a hot, shooting pain. You’ve been stung by a jellyfish. But what do you do now?
First let’s take a look at exactly what’s happening to your leg. Jellyfish have special cells along their tentacles called cnidocytes. Within these cells are harpoon-like structures full of venom, called nematocysts. The nematocysts shoot out when triggered by touch and can penetrate human skin in less time than it takes you to blink.
Once the venom is injected into your skin, the pain, redness and blistering begin. One of the main causes of this discomfort is a type of protein called a porin found in the venom of all jellyfish—and in all their relatives, including corals and anemones, which together form a group of creatures collectively known as cnidarians. Angel Yanagihara, a research professor studying box jellyfish venom at the Pacific Biosciences Research Center at the University of Hawaii, explains that the porins in box jellyfish are fast-acting and “promiscuous:” they are indiscriminate and “will punch holes in all types of cells” including blood, skin and nerve cells. The complex concoction of these proteins varies (along with the stinging cell mechanism) from species to species, which is why we might only feel a small sticky sensation when we come in contact with some anemones, while a box jelly sting may cause a trip to the emergency room or even kill you.
So after you’re stung, you should pee on it, right? Or get someone else to? That’s what you’ve seen on TV—maybe you’re thinking of a certain incident from Friends. But don’t pull those board shorts off too quickly—urine can do a lot of things, but it doesn’t help the sting. It may actually make it worse.
That’s because pouring freshwater—or urine—on the area will change the composition of the solution surrounding the remaining cells and may actually trigger the release of more nematocysts and venom. Instead, experts suggest rinsing the area with saltwater to help reduce discomfort. Before you do any rinsing, however, remove any jellyfish tentacles that remain on the skin, as nematocysts on loose tentacles can continue to sting even after they are detached from the jelly. Making sure that sand stays clear of the wound is also an important task, but likely a difficult one while on the beach. In the case of a box jelly sting, it would be helpful to have Yanagihara nearby with the two treatments she has developed—or even better would be to make use of her preventive ointment before going in the water. Because these aren’t yet available to the public, putting vinegar on the affected area and seeking medical attention are the suggested treatments.
It’s good to have this information in-hand when you go to the beach just in case—though it’s unlikely that you’ll be stung. But that possibility could be on the rise if, as has been suggested, jellyfish numbers are increasing. A study from April 2012 in Hydrobiologia found increasing jellyfish populations in 62 percent of the regions analyzed, including coastal areas of Asia, the Black Sea and the Mediterranean Sea. “Our study confirms these observations scientifically after analysis of available information from 1950 to the present for more than 138 different jellyfish populations around the world,” said Lucas
Brotze Brotz, the lead author of the study in a press release.
However, jellyfish are a difficult species to study: their life cycles aren’t well understood, and catching them by net is not a good option due to their fragile, gelatinous bodies. Because of this, sweeping claims about global changes in jellyfish populations are up for debate. Their historical numbers are largely unknown, making it hard to be sure whether jellyfish populations are increasing over the long term, or whether the increases we see are a part of natural population fluctuations or an artifact of more people reporting sightings. And there is evidence for these caveats: a different 2012 study found that the perceived rise in the number of jellyfish is actually the peak of a normal 20-year boom and bust cycle.
But if jellyfish are increasing globally, it is likely that human influences are the cause. Overfishing has reduced some jellies’ competition for food; increased nutrients running into the ocean create oxygen-depleted environments that jellies can tolerate better than other animals; and warmer water can help some species of jellyfish larvae to grow more quickly. Even jellies without a nasty sting can cause problems, clogging up pipes in nuclear power plants that use seawater to cool their reactors and pushing fish out of the ecosystem.
There still is much to learn about the fascinating and pulsing lives of jellyfish that can help to determine if their populations are increasing long-term. Scientists are making use of observant beachgoers, with websites where you can input your jelly sightings onto a map to generate global data on jelly populations. So if you do have the bad luck to get stung by a jellyfish, remember: wash it with salt water, not pee, and maybe pop your location into the map to help us all learn something from the experience.
Learn more about the ocean from the Smithsonian’s Ocean Portal.
June 7, 2013
Ocean plants produce some 50% of the planet’s oxygen. Seawater absorbs a quarter of the carbon dioxide we pump into the atmosphere. Ocean currents distribute heat around the globe, regulating weather patterns and climate. And, for those who take pleasure in life’s simple rewards, a seaweed extract keeps your peanut butter and ice cream at the right consistency!
Nonetheless, those of us who can’t see the ocean from our window still feel a disconnect—because the ocean feels far away, it’s easy to forget the critical role the ocean plays in human life and to think that problems concerning the ocean will only harm those people that fish or make their living directly from the sea. But this isn’t true: the sea is far more important than that.
Every year, scientists learn more about the top threats to the ocean and what we can do to counter them. So for tomorrow’s World Oceans Day, here’s a run-down of what we’ve learned just in the past 12 months.
This year, we got the news that the apparent “slow down” in global warming may just be the ocean shouldering the load by absorbing more heat than usual. But this is no cause to celebrate: the extra heat may be out of sight, but it shouldn’t be out of mind. Ocean surface temperatures have been rising incrementally since the early 20th century, and the past three decades have been warmer than we’ve ever observed before. In fact, waters off the U.S. East Coast were hotter in 2012 than the past 150 years. This increase is already affecting wildlife. For example, fish are shifting their ranges globally to stay in the cooler water they prefer, altering ecosystems and fisheries’ harvests.
Coral reefs are highly susceptible to warming: warm water (and other environmental changes) drives away the symbiotic algae that live inside coral animals and provide them food. This process, called bleaching, can kill corals outright by causing them to starve to death, or make it more likely that they will succumb to disease. A study out this year found that even if we reduce our emissions and stop warming the planet beyond 2°C, the number considered to be safe for most ecosystems, around 70% of corals will degrade and die by 2030.
Although coral reefs can be quite resilient and can survive unimaginable disturbances, we need to get moving on reducing carbon dioxide emissions and creating protected areas where other stressors such as environmental pollutants are reduced.
More than a hit of acid
The ocean doesn’t just absorb heat from the atmosphere: it also absorbs carbon dioxide directly, which breaks down into carbonic acid and makes seawater more acidic. Since preindustrial times, the ocean has become 30% more acidic and scientists are just starting to unravel the diverse responses ecosystems and organisms have to acidification.
And it really is a variety: some organisms (the “winners”) may not be harmed by acidification at all. Sea urchin larvae, for instance, develop just fine, despite having calcium carbonate skeletons that are susceptible to dissolving. Sponges that drill into shells and corals show an ability to drill faster in acidic seawater, but to the detriment of the organisms they’re boring into.
Nonetheless, there will be plenty of losers. This year saw the first physical evidence of acidification in the wild: the shells of swimming snails called pteropods showed signs of dissolution in Antarctica. Researchers previously found that oyster larvae fail under acidic conditions, potentially explaining recent oyster hatchery collapses and smaller oysters. Acidification may also harm other fisheries.
Plastic, plastic, everywhere
Americans produced 31 million tons of plastic trash in 2010, and only eight percent of that was recycled. Where does the remaining plastic go? A lot of it ends up in the ocean.
Since last World Oceans Day, trash has reached the deep-sea and the remote Southern Ocean, two of the most pristine areas on Earth. Most of the plastic trash in the ocean is small—a few centimeters or less—and can easily be consumed by animals, with damaging consequences. Some animals get hit on two fronts: when already dangerous plastic degrades in their stomachs it leaches toxic chemicals into their systems. Laysan albatross chicks are fed the bits of plastic by their parents in lieu of their typical diet and one-third of fish in the English Channel have nibbled on plastic.
Where have all the fish gone?
A perennial problem for the ocean, overfishing has only gotten worse with the advent of highly advanced gear. Despite fishing fleets going farther and deeper, the fishing gains are not keeping up with the increased effort.
Our brains can’t keep up either: even as we catch fewer fish, we acclimate to the new normal, adjust to the shifting baseline, and forget the boon that used to be, despite the fact that our memories are long enough to realize that most of the world’s fisheries (especially the small ones that aren’t regulated) are in decline.
Thankfully, those responsible for managing our fisheries are aware of what’s at stake. New knowledge about fish populations and their role in ecosystems can lead to recovery. A report from March 2013 shows that two-thirds of U.S. fish species that are closely managed due to their earlier declines are now considered rebuilt, or on their way.
Learn more about the ocean from the Smithsonian’s Ocean Portal. This post was co-authored by Emily Frost and Hannah Waters.
May 17, 2013
Our oceans are taking a beating from overfishing, pollution, acidification and warming, putting at risk the many creatures who make their home in seawater. But when most people think of struggling ocean species, the first animals that come to mind are probably whales, seals or sea turtles.
Sure, many of these large (and adorable) animals play an important part in the marine ecosystem and are threatened with extinction due to human activities, but in fact, of the 94 marine species listed under the Endangered Species Act (ESA), only 45 are marine mammals and sea turtles. As such, these don’t paint the whole picture of what happens under the sea. What about the remaining 49 that form a myriad of other important parts of the underwater web?
These less charismatic members of the list include corals, sea birds, mollusks and, of course, fish. They fall under two categories: endangered or threatened. According to NOAA’s National Marine Fisheries Service (pdf), one of the groups responsible for implementing the ESA, a species is considered endangered if it faces imminent extinction, and and a species is considered threatened if it is likely to become endangered in the future. A cross section of these less-known members of the ESA’s list are described in detail below.
1. Staghorn coral (Acropora cervicornis), pictured above, is one of two species of coral listed as threatened under the ESA, although both are under review for reclassification to endangered. A very important reef-building coral in the Caribbean and the Gulf of Mexico, it primarily reproduces through asexual fragmentation. This means that its branches break off and reattach to a substrate on the ocean bottom where they grow into new colonies.
While this is a great recovery method when only part of a colony is damaged, it doesn’t work so well when most or all of the colony is killed—which often is the result from disturbances afflicting these corals. Since the 1980s, staghorn coral populations have steeply declined due to outbreaks of coral disease, increased sedimentation, bleaching and damage from hurricanes. Although only two coral species are currently on the ESA list, 66 additional coral species have been proposed for listing and are currently under review.
2. The white abalone (Haliotis sorenseni), a large sea snail that can grow to ten inches long, was the first marine invertebrate to be listed under the ESA but its population hasn’t recovered. The commercial fishery for white abalone collapsed three decades ago because, being spawners that jet their eggs and sperm into the water for fertilization with the hope that the two will collide, the animals depend on a large enough population of males and females being in close proximity to one another to reproduce successfully.
Less than 0.1% of its pre-fished population survives today, and research published in 2012 showed that it has continued to decline since its ESA listing more than a decade ago. The researchers recommended human intervention, and aquaculture efforts have begun in an effort to save the species.
3. Johnson’s seagrass (Halophila johnsonii), the lone marine plant species listed, is classified as threatened and makes coastal habitats and nurseries for fish and provides a food source for the also-endangered West Indian manatees and green sea turtles. However, its most important role may be long-term ocean carbon storage, known as blue carbon: seagrass beds can store more carbon than the world’s forests per hectare.
The main threats to Johnson’s seagrass are nutrient and sediment pollution, and damage from boating, dredging and storms. Its plight is aggravated by its tiny geographic range–it is only found on the southeast coast of Florida. The species may have more trouble recovering than other seagrass species because it seems to only reproduce asexually–while other seagrasses can reproduce like land plants, by producing a flower that is then fertilized by clumps of pollen released underwater, the Johnson’s seagrass relies on the sometimes slow process of new stems sprouting from the buried root systems of individual plants.
4. The short-tailed albatross (Phoebastria albatrus) differs from some of its neighbors on the ESA list in that an extra layer of uncertainty is added to the mix: During breeding season, they nest on islands near Japan, but after breeding season ends, they spread their wings and fly to the U.S. In the late 19th century, the beautiful birds are thought to have been fairly common from coastal California up through Alaska. But in the 1940s, their population dropped from the tens of millions to such a small number that they were thought to be extinct. Their incredible decline was due to hunters collecting their feathers, compounded by volcanic damage to their breeding islands in the 1930s.
Today they are doing better, with over 2,000 birds counted in 2008, but only a few islands remain as nesting sites and they continue to be caught as bycatch, meaning that they are often mistakenly hooked by longline fishing gear.
5. Salmon are a familiar fish frequently seen on the menu. But not all species are doing well enough to be served on our plates. Salmon split their time between freshwater (where they are born and later spawn) and the ocean (where they spend their time in between). Historically, Atlantic salmon in the U.S. were found in most major rivers on the Atlantic coast north of the Hudson, which flows through New York State. But damming, pollution and overfishing have pushed the species to a point where they are now only found along a small section of the Maine coast. Twenty-eight populations of Pacific salmon are also listed as threatened or endangered. Efforts on both coasts are underway to rebuild populations through habitat restoration, pollution reduction and aquaculture.
The five organisms listed here are just a few of the marine species on the ESA’s list. In fact, scientists expect that as they learn more about the oceans, they will reveal threats to more critters and plants.
“The charismatic marine species, like large whales [and] sea turtles…were the first to captivate us and pique our curiosity to look under the waves,” says Jonathan Shannon, from the NOAA Fisheries Office of Protected
Species Resources. “While we are learning more about the ocean and how it works every day, we still have much to learn about the different species in the ocean and the health of their populations.”
Learn more about the ocean from the Smithsonian’s Ocean Portal.
March 15, 2013
Whether they’re on a rain-soaked sidewalk, in the compost bin or on the end of a fish hook, the worms most people know are of the segmented variety. But what about all the other worms out there?
With more than 1,000 species of ribbon worms (phylum Nemertea), most found in the ocean, there is a huge range of sizes and lifestyles among the various types. A defining characteristic of ribbon worms is the presence of a proboscis—a unique muscular structure inside the worm’s body. When attacking prey, they compress their bodies to push out the proboscis like the finger of a latex glove turned inside-out.
Here are 14 other fun facts about them:
1. The largest species of ribbon worm is the bootlace worm, Lineus longissimus, which can be found writhing among rocks in the waters of the North Sea. Not only is it the largest nemertean, but it may also be the longest animal on the planet! Uncertainty remains because these stretchy worms are difficult to accurately measure, but they have been found at lengths of over 30 meters (98 feet) and are believed to even grow as long as 60 meters (197 feet)—longer than the blue whale! Despite their length they are less than an inch around.
2. The smallest ribbon worm species is less than a centimeter long, and resembles a piece of thread more closely than what we think of as a worm.
3. Ribbon worms have highly developed muscles that allow them to contract their bodies, shrinking to a tenth of their extended length when threatened.
4. Talk about stretching: ribbon worm muscles don’t just contract–they can also expand, allowing some species to swallow prey (such as other kinds of worms, fish, crustaceans, snails and clams) that are more than double the width of their narrow bodies
5. The proboscis varies among the species. Some are sticky or have suckers to help grasp prey, and some species, like those in the order Hoplonemertea, even stab their prey with a sharp spike, called a stylet, on the proboscis.
6. Because the stylets often are lost during an attack, the worms continually make and use replacements that they have in reserve in internal pouches.
7. As a second line of defense, many ribbon worms are poisonous and taste bad. Several species contain tetrodotoxin, the infamous pufferfish venom that can induce paralysis and death by asphyxia. It’s still not known exactly how the toxins are produced—they may linger in the worms from ingested bacteria—but they deter predators from taking a bite. Some even eject toxins from their proboscis.
8. Some ribbon worms sneak up on their prey, lying in wait buried in the sandy seafloor. One species of worm will pop up from its home in the sand when a fiddler crab walks over. The worm will cover the prey with toxic slime from its proboscis, paralyzing the crab so the ribbon worm can slide into a crack in the shell and eat the crab from the inside out.
9. Not all ribbon worms are predators – some are parasites. One genus of ribbon worms, Carcinonemertes, lives as a parasite on crabs, eating the crab’s eggs and any animals that it can find from the confines of its host.
10. Most ribbon worms produce a slippery mucus that covers their bodies and helps them to navigate through the mud and rocks on the ocean floor.
11. Some also use the mucus as a protective coat to keep from drying out when exposed to air during low tides. Others use their proboscis to move by attaching it to an object and pulling themselves forward. This same mucus makes them hard to catch! And not only by predators: scientists trying to catch the worms have a difficult time.
12. Marine ribbon worms usually have separate sexes and temporary sex organs. Rows of gonads line the inside of their bodies to produce either eggs or sperm. When they are ready to be released, the gonad ducts form on demand and are reabsorbed after reproduction.
13. Most ribbon worms have direct development: a miniature version of the worm hatches from a fertilized egg. However, the young of one group of ribbon worms, the heteronemerteans, emerge in a bizarre larval stage that looks like a flying saucer. After a few weeks to months living and feeding in the open ocean, a small worm develops inside and, when it’s ready, it eats its way out of the original larva encasing. Then the worm falls to the sea floor where it spends the rest of its life.
14. Many ribbon worms can regenerate when a predator takes a bite, healing their broken ends. One worm species, Ramphogordius sanguineus, has an exceptional ability to regenerate: if any part of their body is severed (except for the very tip of their tail where there are no nerves), it can regrow into a new worm. This new individual may be smaller than the worm it came from, but more than 200,000 worms can result from an individual that is only 15 centimeters (6 inches) long!
Learn more about the ocean from the Smithsonian’s Ocean Portal.
February 13, 2013
We often hear stories of animal love—tales of rare monogamy in the animal kingdom where life-long love is implied. But there is a distinction between romantic love and an efficient mating system. Here’s a look at some ocean animals to see what is really going on.
Albatrosses Get ‘Romantic’ to Increase Chick Survival
Albatross relationships seem especially relatable to humans. These long-lived and highly-endangered birds will court each other through ritual dances for years. Albatrosses are slow to reach sexual maturity, and some species even delay breeding for several years to learn specific mating rituals and to pick the perfect partner. The courtship behavior slows down once the pair bonds (an all too familiar aspect of human relationships). Once a pair is comfortable and breeding commences, they will return to each other and the same spot each year; for most albatross species, the bond lasts their entire life.
So is it love? The biological reality is that albatrosses only lay a single egg a year. With both parents fully invested in chick survival, their genetic heritage is most likely to survive. It may seem like love, but with those low reproduction rates no parents can afford to be deadbeats.
Seahorses Bond to Improve the Odds of Birth
If albatross relationships are reminiscent of fairytale romance, seahorses might be considered the swingers of the sea. Many seahorse species will bond with a mate, but that bond often lasts only through a single breeding season or until a more attractive female comes along. But, monogamy in this case is useful since it can be hard to find fellow seahorses due to poor swimming skills and low densities.
There is evidence that the longer that partners are together, the more successful at breeding they become and the two are able to produce more offspring per brood. One species of seahorse does appear to stick with a single mate for life: the Australian Hippocampus whitei. Practice makes perfect!
Two Angelfish Make a Strong Defense
Typically in pairs, French angelfish (Pomacanthus paru) help each other defend their territory against other fish. The couples have been observed spending extended periods of time together, exhibiting more of a monogamous social structure. Genetic monogamy (i.e. testing fertilized eggs to confirm they come from a single father) hasn’t been confirmed, but there have been observations of pairs traveling to the water’s surface to release their eggs and sperm together.
Monogamy is not that common in fishes, and it is mostly found in tropical and subtropical waters. Care needed from two parents, joint defense of territories, and difficulties in finding a mate all can play a role.
A Permanent Glass Home for Shrimp
These intriguing glass sponges, called Venus’s flower-baskets (Eupectella aspergillum), are made of flexible silica that can better transmit light than our man-made fiber-optic cables. And many of these beautiful deep-sea sponges are also home to a monogamous pair of shrimp.
Several species of shrimp find refuge in these sponges, but due to the limited space found within the fine-mesh silica, only two adult shrimp can fit inside—and they are stuck there for life. The two spend their days cleaning the sponge and eating whatever bits of food manage to flow through. After they breed, their small offspring can squeeze through the holes in the mesh to escape, but eventually they will settle into a new home with their own imprisoned mate.
The gift of this sponge, taken from the deep with the two dead shrimp still trapped inside, is considered good luck for couples marrying in Japan. It seems as though young human couples are not the only ones to share tight living spaces.
Learn more about the ocean from the Smithsonian’s Ocean Portal.