Blue Glaucus

Domain: Eukarya
Kingdom: Animalia
Phylum: Mullusca
Class: Gastropoda
Order: Nudibranchia
Family: Glaucidae
Genus: Glaucus
Species: Glaucus atlanticus

The other day, I got a strange text from my dad talking about an article that he found on the Internet describing a blue dragon that had washed up in Texas. He seemed really excited to show me the article because he thought I could blog about it. Well, “blue dragon” didn’t ring any bells, and I thought that it might have been an oarfish, which is dragon-esque. Instead, what I found is a nudibranch, most commonly known as a sea slug.

Glaucus atlanticus goes by many common names: blue glaucus, blue dragon, sea swallow, and blue sea slug, to name a few. No, it does not look like any slug you might have seen or land.

The creature has what looks like a head and a tail. Along its body are three pairs of fan-like appendages that look like wings. The blue sea slug can grow up to 1.2 inches (3cm) in length, which would make it the smallest dragon in the Guinness World Record book. However, it is not the smallest sea slug!

Most sea slugs live on the seafloor. They can live on coral, or the sandy substrate, or even rocky surfaces. Glaucus atlanticus isn’t like its cousins, though. Instead, they are a pelagic sea slug, meaning they live in the open water column. They have been sighted more often up towards the ocean’s surface.

The blue sea slug floats in the water column by storing an air bubble in its body, acting like an air bladder in fish. If it hangs out near the surface, how does it hide from sea birds?

Glaucus atlanticus has a special coloration that allows it to blend into its surroundings called countershading. The blue sea slug floats on its backside, showing the bright blue underbelly toward the sky. The blue helps it blend into the waves and makes it hard for sea birds to see the creature. On the other side, it is a grayish color that blends in with the surface water from below, making it nearly invisible to its underwater predators.

Countershading isn’t the only defense it has against predators. In fact, like most sea slugs, this is a creature you don’t want to touch—no matter how pretty it looks!

One of the things blue dragons consume is the Portuguese man o’ war, a type of hydrozoan known to give nasty stings to beach-goers. The Portuguese man o’ war has long tentacles, almost 30 feet long, which are full of stinging cells.

When the blue dragon consumes the Portuguese man o’ war it stores the hydrozoan’s stinging cells in those fan-like appendages. When a diver or predator gets too close, the blue dragon will brush up against the perceived threat and sting them with the stinging cells. It’s been reported that a sting from a Glaucus atlanticus hurts more than a sting from a Portuguese man o’ war—so watch out for these critters when swimming! They’re found in the warm waters of the Pacific, Indian, and Atlantic Oceans.

If anyone has any suggestions or requests, like this one, let me know! I want to write about what interests you.

Sources and links:
Reef Creature Identification: Florida, Caibbean, Bahamas 3rd edition by Paul Humann, Ned Deloach, and Les Wilk ⇐has dive-related news articles as well

Sylvia Earle

“Everyone should be literate about the ocean. No child should be left dry!”
–Dr. Sylvia Earle

Today, I want to introduce you to “Her Deepness,” Dr. Sylvia Earle.

In 1935, Sylvia Earle was born in New Jersey, United States. At the age of 13, she and her family moved to Clearwater, Florida on the Gulf of Mexico. Being so close to the ocean, Sylvia heard her life’s calling and soon began learning all she could about the ocean and its creatures.

Sylvia worked her way through college, laboring in college labs to help pay for her schooling. At the University of Florida, she studied oceanography and biology. She went on to study at Duke University, earning her master’s degree and eventually her PhD in phycology (the study of algae) and she has made it one of her life’s projects to catalogue all plant-life in the Gulf of Mexico.

But she didn’t stop there.

She has worked aboard more than 50 oceanic expeditions and clocked more than 7,000 hours underwater—that’s more than 291 days. In 1970, she led an all-female expedition called Tektite II, Mission 6. Sylvia and four women dived 50 feet below the surface of the ocean and lived underwater in a small structure for two weeks. When they resurfaced, Sylvia Earle became a celebrity outside of the science community, and everyone wanted her as a speaker. Since then, she has used her fame and her voice to be a leading advocate for the ocean.

In 1979, Sylvia Earle set a new record off the island of Oahu for deep sea diving. In a submersible, she traveled down to a depth of 1,250 feet. While using a special pressurized suit, she walked along the ocean floor untethered for two and a half hours. As she explored these previously unknown depths, her only connection to the vessel was a communication line; nothing connected her to the world above. Her record still stands today.

Sylvia Earle started two engineering companies, Deep Sea Engineering and Deep Sea Technologies, which design undersea vehicles to help scientists explore the deep reaches of the ocean. She served as the first female Chief Scientist at the National Oceanic and Atmospheric Administration (NOAA). She is also the founder of Mission Blue, an organization that is dedicated to protecting the world’s oceans.

Mission Blue’s mission is to help establish “Hope Spots” around the world. Hope Spots are areas that are deemed vital to the health of the ocean by providing essential services, areas like coral reefs and seagrass beds. Mission Blue sends out researchers to explore new areas and to gather data that proves the locations’ importance to the ocean, and thereby to us. With the data, Mission Blue tries to convince governments to establish these Hope Spots, or marine protected areas.

Dr. Sylvia Earle is truly an inspiration, a woman I strive to become. I highly recommend looking into her life’s story, at least her career. She has published some books over the years that I would love to read, including her 1979 deep sea adventure! She’s also one of the speakers in the videos on NeMO-Net, the coral-identifying game created by NASA.
Sources: ⇐very in-depth article into her life and research ⇐if you want to see her TED speech ⇐if you want to check out Mission Blue and Hope Spots


Everybody likes to play games, especially video games. Whether it’s a high-resolution, top-notch game with amazing graphics or a simple game of solitaire on your computer, everybody plays games. Even my mom plays Borderlands by GearBox and 2kGames, my dad plays card games on his computer between grading his students’ assignments, and my half-blind aunt plays mahjong on her Kindle.

Everybody likes to play games, and NASA decided to take advantage of that.

One of the difficulties in studying coral reefs is the limitations we have as humans. It’s best to study them in person, but because reefs are underwater, we need tanks to breathe artificial air so we don’t drown while we collect data. We also can’t spend the whole day diving without dying.

Reefs also are pretty spread out and aren’t always close to the shore, so it takes time to travel to all of them and collect data. Funding is an issue because boats and fuel cost money, along with the standard dive equipment, air for the tanks, and the equipment for research.

We also don’t know where all the reefs are in the ocean. In fact, we have mapped out more of the surface of the moon than we have our own oceans—so, who knows where all the coral are!

Speaking of the moon, NASA decided to help coral researchers. They took the same equipment they use to look at stars and pointed them toward our oceans. We can’t use standard camera lenses to photograph reefs from above because of a special law called Snell’s law or the law of refraction.

The law of refraction—which I described in an earlier post—explains how light bends (or refracts) as it passes from one medium to another. Refraction makes taking aerial shots of coral reefs problematic because the subjects become distorted in the image. Using their fluid-correcting lenses, which are manufactured to take Snell’s law into account, NASA has deployed drones and small planes to take pictures of reefs around the world and produce 3D images of what the reefs should look like underwater.

That’s great and all, but all those coral need to be identified, which can take thousands of man hours and hundreds of people. By the time all of the pictures are processed and the coral identified, the reefs may look drastically different and all that data may no longer be relevant. So NASA decided to use the help of video gamers and citizen science to identify all the coral in their photos.

The Neural Multi-Modal Observation and Training Network (NeMO-Net) was created to help marine scientists identify and protect coral. The NeMO-Net game allows players to look at real 3D images of reefs and identify different families of coral, what’s just sand or an invertebrate on the seafloor, and other objects. Players color-code the image based on what they see, so each coral family has its own color, and then players upload their image to a database where other players and scientists can agree or correct what was submitted.

The approved images are used to train a supercomputer at the Ames Research Center to look through collected images and correctly identify what it sees, so that eventually the supercomputer can do it on its own. A supercomputer doesn’t need to sleep or get bored with repetition, so it can go through images a lot faster than a person can. This way, we can get a baseline for our reefs now, and we will be able to identify when there’s a problem so that we can try and fix it before it’s too late.

I have installed the game on my tablet. It’s a lot of fun, and I find it to be really relaxing. Most people can play the game; it doesn’t matter if you’re in elementary school or have a grandkid in elementary school.

NeMO-net is a simple game that allows you to go on virtual dives and identify things on the reef or coastline. You gain experience with each picture you submit, and you slowly level-up your way up the food chain. You can also gain badges and achievements for playing the game.

The best part, in my opinion, is that the game comes with videos that you can unlock. There are video field guides on various creatures you see, how the technology works, and the process behind everything. There’s also written information on the various families of coral you can identify in the game.

NeMO-net is a great way to spend your time and to get into citizen science without any complex understanding of the ocean. And it also makes you feel like you are part of the NASA team; in my case, I feel just a little bit more important to the coral I want to protect.


Law of Refraction

My husband’s late grandfather was a fascinating man and a brilliant engineer. When I first met him, he asked me if I knew about Snell’s law. At the time, I was still in college and hadn’t taken physics yet, but it sounded familiar. When he started to explain it to me, I recognized it as the law of refraction. I remember his eyes lighting up when I caught on. Later, I learned that it was one of the ways he judged a person, and he had deemed me worthy.

I bring up this physics term because it also relates to water.

The easiest way to explain Snell’s law is with a physical example.

Take a smooth, clear glass and fill it full of water. The glass or cup can’t have any ridges or funky shapes in the glass, or the demonstration might not turn out right. A pub-style pint glass works well. Next, find a straw or a pencil—I recommend an eco-friendly steel or biodegradable paper straw—and put it in the water. Now, spend some time looking at the glass from different angles. Look from above and at eye level with the water line, and move the straw around.

What you should see is that the straw doesn’t appear perfectly straight. Sometimes the submerged half of the straw seems slightly thicker. Sometimes the two ends don’t line up, and there may be a slight bend in the straw that isn’t actually there. From above the end of the straw might look a little curved to one side.

The law of refraction governs how light bends or refracts as it passes from one medium to another, like from the air to the water. This law explains why things are not always where they appear to be in the water as seen from the air.

Luckily for us, we have a straight forward equation we can use figure out the refracted angle, though you may need to do some more independent reading to understand why it works. Other creatures don’t have mathematical formulas to help them, though.

For example, an osprey flying over a body of water will have to learn how to accurately find its prey underwater or it will starve. From the air, a fish may appear to be in one spot but may actually be a few feet to the right. If the osprey misjudges where the fish is the first time and doesn’t catch it, then its chances of getting a fish the second time are greatly reduced because it lost the element of surprise. Birds of prey must learn to adjust to this optical illusion, a failed attempt at catching prey is a waste of energy.

Another example is the Australian archer fish, a fish that has developed the ability to spit jets of water at bugs on overhanging tree branches. Archer fish learn to do this because during the drought season, their normal food supply may become scarce, so they spit at bugs to try and knock them into the water to eat.

The same distortion exists for the archer fish below as it does for birds from above. The bug that the archer fish wants to knock off its branch may actually be three inches to the left instead of straight above the fish. So, through trial and error, archer fish learn to calculate where the bugs are above the water.

At the aquarium I volunteer at, one of my favorite activities is talking to guests about the archer fish’s ability to spit water at bugs on overhanging branches. Occasionally, we’re allowed to demonstrate this by getting a live cricket on a stick that we extend over the exhibit. Very quickly, little jets of water are arching out of the water as the fish try to knock the cricket into the water.

The fish that successfully hits the cricket isn’t always the one to eat the cricket. In fact, sometimes the pig-nose turtle in the tank gets the cricket. And sometimes, the volunteer (reads as: me) doing the demonstration gets spit in the face by the archer fish. But who can get mad at that? It actually made my day!



Photo of an osprey by Frank Cone from Pexels

Domain: Eukarya
Kingdom: Animalia
Phylum: Chordata
Class: Aves
Order: Accipitriformes
Family: Pandionidae
Genus: Pandion
Species: Pandion haliaetus

The last bird I spoke of was a flightless bird, the African penguin. Penguins are the only flightless aquatic birds. Today, I’ll be discussing an aquatic bird that has been seen on every continent but Antarctica: the osprey.

Pandion haliaetus is a bird of prey that often gets mistaken for a bald eagle, at least in the United States. From far below, these two birds can look very similar. Both species are large (around two feet tall or more) with wing spans of five to six feet. Ospreys and bald eagles frequent many of the same hunting grounds too: rivers, lakes, estuaries, and other coastal areas.

They way to tell an osprey from a bald eagle is by the coloring. If the birds are flying overhead, a bald eagle has a dark underside while an osprey has a white underbelly and legs. If you get close enough to see their heads, look for the dark stripe that streaks away from the eyes of the osprey.

Ospreys primarily feed on fish. They soar high above the water until they locate their prey. Then the bird drives straight for the water and hooks its talons around a fish. Pandion haliaetus have specially adapted feet that allow them to keep hold of their slippery prey: their talons are long and curved, and the soles of their feet are spiny, the better to grip their prey. After catching its prey, the osprey returns to its nest high above the ground.

Fun fact: In the US, bald eagles will often attack ospreys, trying to get the slightly smaller bird to release its fish. Once the osprey releases the fish, the bald eagle stops pursuing it and grabs the fish from the air.

P. haliaetus are migratory birds. They like to spend their winters in warmer climes, so they travel to the southern hemisphere when the northern hemisphere cools for winter, much like a lot of older humans I know.

Ospreys like to nest high in the trees or on the crags of a seashore or estuary. However, they have made use of artificial places, as well; many of their nests have been found on top of street lights and telephone poles. Often, the ospreys will return to old nests for many years.

Ospreys have one brood a year, and their nests contain two or three eggs. Seven weeks after the chicks hatch, the fledgling ospreys leave the nest to venture off on their own.

In the 1950s-1960s, the osprey populations were declining drastically. Researchers discovered that their eggs were becoming too brittle, and the osprey parents were accidentally breaking the eggs when they laid on them to keep them warm.

Studies showed that a common chemical of pesticides at the time, Dichlorodiphenyltrichloroethane (DDT), was found to be the cause of the brittle eggs, through a process called biomagnification. The process is a bit complicated to explain here; essentially, it’s a process whereby harmful chemicals build up as they travel up the food chain until they eventually become quite lethal to those at the top, such as predatory birds and humans.

Fortunately, this is not a sad tale like that of Stellar’s sea cow.

In 1962, Rachel Carson published the book Silent Spring wherein she described the effects and consequences of DDT. She made public the drastic declines of predatory birds, like the osprey and the bald eagle, and the cause of it. From Silent Spring, a movement was born, DDT was banned by the Environmental Protection Agency, and stricter regulations on pesticides were passed.

Since then, the populations of osprey and bald eagles have bounced back with vigor. Ospreys have been labeled as least concern, meaning that they are no longer threatened by extinction.

I don’t believe that I have ever seen an osprey despite living near the coast. But I wanted to share this bird with you, along with its connection to Silent Spring as a reminder that not everything is doom and gloom in the world, at least when it comes to extinction and climate change. I wanted to show this as proof that we are not too far gone, that there is still hope for the future.

The book Silent Spring saved the ospreys and bald eagles of North America. If it was done once, it can be done again.

Who knows, maybe you will be the author of the next Silent Spring that awakens the world. Or maybe you’ll be one of the readers, doing your part to persuade a government.

Just remember that not all hope is lost.

Sources and links:
Ocean: The Definitive Visual Guide by the American Museum of History
Smithsonian Nature Guide: Birds by David Burnie <—some info on Silent Spring and DDT 

Sea Whip

Domain: Eukarya
Kingdom: Animalia
Phylum: Cnidaria
Class: Anthozoa
Order: Gorgonacae
Family: Gorgoniidae
Genus: Leptogorgia
Species: Leptogorgia virgulata

I’ve realized that so far the only corals I have mentioned have been hard corals—reef builders. I will admit, that I like more hard corals than soft, but that doesn’t mean soft corals aren’t worth talking about. Continuing with my Chesapeake Bay theme, I’m going to talk about a native soft coral, the Sea Whip.

Cue the 80s music: “Crack that whip!” “Just whip it!”

The major difference between hard and soft corals is the composition of their bodies. Hard corals have permanent, rigid exoskeletons that house the coral polyps. These structures require large amounts of energy to build, which is why it can take a year for hard corals to grow just an inch, at best. Soft corals, however, lack that rigid calcium carbonate skeleton. Instead, soft corals are mostly made of living tissue that allows the soft corals to assume more creative shapes.

Sea whips, Leptogorgia virgulata, have long, thin branches that can grow up to a meter long. Their coloring can vary from red, to tan or orange, to purple. The polyps are always white, so sea whips look like they’re covered in white fuzz. Most soft corals are more colorful than their harder cousins.

Sea whips are found in reef environments and can tolerate low levels of salinity, so they are most common in nearshore areas that are more influenced by the tide. They range from New York to the Chesapeake Bay and from Florida to Brazil. In the Chesapeake Bay they thrive in the salty waters of the lower section of the bay.

L. virgulata are suspension feeders, so the polyps use their long tentacles to snag plankton and other tiny particles that are suspended in the water. When sea whips are born, the tiny polyps are carried by waves and currents. When they reach adulthood, so to speak, they become sessile meaning they cannot move from the hard substrate they land on. So they rely heavily on water circulation to stir up the water and bring in more plankton and nutrients for them to feed on.

I have yet to see a sea whip while diving, which is something I wish to change. But I wanted to share this soft coral to show that not all corals are found in tropical places, and that corals can be a lot more diverse than we think. And I’m happy to report that as of this writing, the populations of sea whips in the Chesapeake Bay and other monitored areas are considered stable!

Sources and more info:

Common Bottlenose Dolphin

A pair of bottlenose dolphins (Tursiops truncatus) swim beneath the surface. Sandy Ridge, Little Bahama Bank. Bahamas. Photo taken by Dr. Alex Mustard, more can be found at

Domain: Eukarya
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Cetacea
Family: Delphinidae
Genus: Tursiops
Species: Tursiops truncatus

So long and thanks for all the fish!

Do you know the significance of the number 42? Bottlenose dolphins sing a song about Earth’s destruction; quick, ask them before they leave the planet!

The world’s about to be destroyed
There’s no point getting all annoyed
Lie back and let the planet dissolve around you

Never mind; the dolphins are too busy. Forty-two is the answer to the ultimate question of life, the universe, and everything—at least, according to the super computer Deep Thought and Douglas Adams in The Hitchhiker’s Guide to the Galaxy!

For me, this is the 42nd post on this blog, and I thought I’d be funny about it. So, no, the world is not going to end and all the bottlenose dolphins aren’t breaking out into song before jetting themselves out of the ocean and into space. If you haven’t seen the movie or read the books, I highly recommend them.

Now, let’s get back to our regularly scheduled programming!

The common bottlenose dolphin, Tursiops truncatus, is one of the most exposed dolphins in the world. They are very common in zoos and aquariums. They make appearances in movies or even star in them, like Flipper. They also like to hang around boats and can be seen close to the beach. When people think of dolphins, they usually imagine a T. truncatus.

Bottlenose dolphins are found in a variety of habitats around the world. Their distribution stretches from the temperate waters of the Northern Hemisphere to the temperate waters of the Southern Hemisphere. Local populations of the common bottlenose dolphin can be found along every continent but Antarctica.

Tursiops truncatus have a wide head and body, short stubby beak, long flippers, and a relatively tall dorsal fin. These dolphins have a crease between the beak and the melon that allows researchers to distinguish common bottlenose dolphins from similar-looking species, like the Rough-toothed dolphins.

The common bottlenose can be found inshore of most coasts, living in or near bays, estuaries, coral reefs, or even the mouths of rivers that link directly to the sea. Other populations of dolphins can be found offshore in deeper waters. Offshore bottlenose dolphins look a little different from their inshore relatives with thicker, darker bodies and shorter flippers, though genetically they are the same species.

Bottlenose dolphins are extremely sociable creatures, between themselves and other animals as well, including pilot whales and human swimmers. Despite their stereotypical friendliness, they have been reported to be unfriendly towards other species of dolphins. Along with acting sociable, dolphins emit a wide variety of clicks, squeaks, and squeals that they use to communicate with each other and other pods of bottlenose. Research suggests that each dolphin has a specific sound associated with it, like a name, that other dolphins use.

T. truncatus are highly intelligent creatures. Depending on their prey, the dolphins use various tools and techniques to catch their food. Some use echolocation, the emission of high frequency sound, to locate and confuse fish. Others have been seen rushing a school toward the shore, getting the fish nearly beached before the dolphins catch and eat them.

The diet of the dolphin changes depending on where the pod is located. For instance, inshore dolphins may have more crustaceans and shrimp in their diet while offshore bottlenose have more deep sea fish and squids in theirs. Bottlenose dolphins are remarkably adaptable, even to the extent of learning to identify fishing vessels and shrimp boats, and incorporating the fisherman’s actions into their hunting behavior.

Overall, their population numbers are good. The species as a whole is not a concern for extinction. Local populations, however, are decreasing due to viral outbreaks, weaker immune systems due to biotoxins and pollution, loss of habitat, and depleted fishing stocks. On a smaller scale, many local populations of inshore bottlenose dolphins need help.

When I first got interested in the ocean, I wanted to work with dolphins. In elementary school, I had a well-worn book on dolphins and sharks that was a companion novel to a Magic Treehouse book. I was so proud of it!

Now my focus has changed to coral, and I have a love/hate relationship with dolphins. I absolutely love dolphins; they are beautiful, intelligent creatures that want nothing more than to eat and play—and boy, do they play! However, sometimes I feel that they get too much attention from the public, and other sea creatures are hurt by it, as in the example of dolphin-safe tuna.

I don’t have time to get into the history and nuances of dolphin-safe tuna; I’ll leave that topic for a future post. The common bottlenose is one species that I’ve loved since I was a child. My biggest complaint is that dolphins get more empathy—because they are warm-blooded creatures like us—than any other creature in the ocean, except for maybe polar bears. This lack of human empathy toward cold-blooded creatures can have a negative impact on the ocean, and, ultimately, dolphins to.

Sources and links:
Ocean: The Definitive Visual Guide by the American Museum of Natural History
National Audubon Society: Guide to Marine Mammals of the World by Randall R. Reeves, Brent S. Stewart,

Alexandrium monilatum

Domain: Eukarya
Kingdom: Prostita
Phylum: Dinophyta
Class: Dinophyceae
Order: Gonyaulacales
Genus: Alexandrium
Species: monilatum

After spending some time talking about the horrors of invasive species, let me throw you a curve ball. We should all agree that invasive/nonnative species are harmful to us and the environments that they infiltrate. However, not all native species are good for their environment either.

How can organisms that are part of the natural balance of their environment be bad for it?

The simplest explanation I can give is this example. Our bodies need potassium to function properly, which we get from food like bananas. If our bodies don’t have enough potassium, then our muscles cramp and we can become stiff and sore. If we consume too much potassium, then it can poison and even kill us. Don’t worry, though; you would have to consume a truck load of bananas in a single day for that to happen.

Like our own bodies, environments need everything in moderation.

Alexandrium monilatum is a single-celled dinoflagellate found in the warm waters of the Atlantic Ocean, Gulf of Mexico, Caribbean Sea, parts of the Pacific Ocean, and the Chesapeake Bay. It is a special kind of bioluminescent algae; when agitated, the organism produces its own light in the form of a soft blue glow.

This dinoflagellate can reproduce sexually and asexually, meaning it can use its own genetic material to make copies of itself without the use of other individuals. It can also produce chains of individuals, ranging from 2 to 80 A. monilatum per strand.

A. monilatum uses photosynthesis to create its own food, making it a phototroph. It is preyed upon by small fish and filter feeders, making it part of the base of the food chain. So how can this armored alga be a bad thing? It sounds so productive, and it even glows blue at night when waves stirs the water!

The problem with A. monilatum is that it is considered a Harmful Algal Bloom (HAB) species. When conditions are right, this species will reproduce faster than it can be consumed by its predators, causing an algal bloom in the water. Blooms are large patches of algae that are seen by the naked eye, meaning there are millions of individuals concentrated in a single area.

Blooms are considered a problem because the water contains a finite amount of nutrients available to the algae. Once the supply runs out, it’ll take time to replace those needed nutrients. So these blooms are extremely productive for a short time, before the algae run out of food and die. When they die, they start to decompose. The process of decomposition takes up a lot of oxygen, and without the photosynthesizers there to replace the oxygen being used, the water becomes hypoxic—or worse, anoxic.

Once the amount of dissolved oxygen in the water is depleted, the area becomes a dead zone, and all the fish and other marine organisms either leave or suffocate in the water. Dead zones aren’t always permanent; however, they are still an inconvenience to the marine life and to us and should be prevented at all cost.

It is not my purpose to make Alexandrium monilatum out to be a bad guy, just to show that even native species can harm their environment under certain conditions. Algal blooms, or red tides, can be caused by a steep increase in important nutrients found in fertilizers, which enter the water as run-off from nearby farms, gardens, and agricultural facilities. A boom in available food causes a boom in creatures that depend on it, and that’s true no matter the species.

Bioluminescent algae are fascinating. I was lucky enough to swim at night in a lake full of a species of bioluminescent algae, though I’m uncertain what species it was. It was a magical experience that I will never forget, so I was excited to talk about A. monilatum and to discuss the importance of balance within an ecosystem.

Sources and more info:

Invasive Species

Invasive is such a harsh word. How can a natural creature be considered an invasive species? Nobody likes weeds, but everyone likes pretty fish and colorful birds—so, how can those be considered dangerous?

An invasive species is any living organism that is found outside of their native environment and has or will cause harm. The harm it can cause can be to the nonnative environment itself, the economy, or humans, or a combination of the three.

The zebra mussels that I’ve spoken about are an example of an invasive species in the United States. They are native to the freshwaters of Eurasia but somehow made it to the United States in the 1980s. Wherever the zebra mussels have been found, outside of Eurasia, they have outcompeted all native species and have changed the environments that they have invaded.

Another example is the lionfish. Its native habitat is the Indo-Pacific Ocean, however, it has made its way to the Atlantic Ocean. It reproduces rather successfully and has no natural predators in the Atlantic waters, so it has decimated many coral reef populations by devouring the herbivorous fish that help keep the reefs clean of algae. Without the algae eaters, the coral are smothered by the thick blankets of algae that naturally grow on them.

Not all invasive species are easy to comprehend at first. For instance, in many countries, domesticated cats and dogs are considered to be invasive species. How can Mittens or Spike be considered invasive? Humans absolutely love them and they (mostly) love us!

Dogs, and especially cats, are considered invasive species in many countries outside of Europe. They were brought over during the time of colonization, and their populations quickly grew unchecked. Dogs threaten native small animal populations, and cats wreak havoc on the native bird populations. For example, the Galapagos penguin population has been hit hard by the invasive house cat populations in South America.

Invasive species don’t have to look exotic. Sometimes they look normal, or they’re hard to notice at all. Invasive species can include plants, animals, fungi, insects, and microbes. And their effects on the local populations can be devastating, as when settlers first encountered native people, and the germs the settlers brought with them killed a lot of the native people of the land who did not have the same immunities built up as the settlers did.

Invasive species can also cause harm in other ways. New microbes introduced to an area can cause illness in people. Insects that have hitchhiked in shipping containers can run wild in new places and hurt the people there, like invasive species of hornets or spiders. Invasive jellyfish can fill the waters and harm beach goers.

Invasive species can even cause harm economically. Invasive hornets destroy beehives that produce honey to be sold. Zebra mussels clog pipes and encrust boats; it costs a lot of money to remove them, and it’s usually not a one-time expense. Lionfish have made coral reefs barren, reducing the populations of game and harvestable fish to low numbers, and impacting aquatic tourism.
Luckily, there are ways to handle invasive species. The best way is to prevent them from entering delicate ecosystems that they don’t belong to. For humans, that means being more careful when transporting food and supplies over long distances. It means finding new owners for exotic animals when you no longer want or can care for them—don’t just release them into the wild!

There are also ways to reduce invasive species numbers. For instance, many places around Florida and the Caribbean offer cash prizes for lionfish through spear-hunting competitions. Or you can encourage local chefs and restaurants to serve invasive species on the menu. The National Aquarium in Baltimore, Maryland frequently serves invasive fish in their diner.

I’ve eaten lionfish, and it’s pretty tasty! Mine was served Jamaican style, featuring a lot of spices that I wasn’t used to, but if prepared properly, it’s a great fish to eat. I’ve also had invasive catfish that was found in our local waters, and it didn’t taste that different from the native catfish, just maybe a little sweeter. So there are all kinds of ways to deal with invasive species, but it’s up to us to keep them in check!

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Zebra Mussels

Domain: Eukarya

A colony of zebra mussels (Dreissena polymorpha), living in freshwater. Photo by Dr. Alex Mustard, find more at

Kingdom: Animalia
Phylum: Mollusca
Class: Bivalvia
Order: Myida
Family: Dreissenidea
Genus: Dreissena
Species: D. polymorpha

Today, we’re going to talk about zebra mussels. We’re not going to talk about zebra muscles like I had originally written down on my blog schedule. Honestly, why would I talk about the muscles of a zebra? They’re not even aquatic!

I know that was a lame introduction. It just doesn’t have enough strength to land a clever opening—maybe it needs more mussels…

Okay, I’ll stop!

Zebra mussels, D. polymorha, are freshwater bivalves native to Eurasia. Bivalves are shelled creatures; specifically mollusks with two shells that close together, like clams and oysters. Zebra mussels are about an inch long and are shaped liked a stretched out “D”. They are named from the black, zigzag patterning on their shells.

Humans can be so creative with their naming schemes.

Zebra mussels have a relatively short life span, between 2‒5 years, reaching reproductive maturity at 2 years of age. Each female can produce up to a million eggs per year, spewing them into the surrounding water and using the currents to transport the eggs.

The reason I’m bring up D. polymorpha is because it is an invasive species in the United States and Canada. The mussels were first discovered in the early 1980s near the Great Lakes and are believed to have been transported by accident in the ballast water of a ship. Since then they have been found in the Great Lakes, the Mississippi and St. Croix rivers, and the Chesapeake Bay.

Why are the zebra mussels bad for these environments? Don’t they help filter the water in their surroundings, and isn’t that a good thing?

In their natural habitat their job as filter feeders is absolutely amazing; in other habitats, it can have devastating effects. In fact, zebra mussels are so efficient as filter feeders that they can clean a body of water of particulates in record time, faster than the native filter feeders. But this is not a good thing.

The environments that the mussels invade have a special balance that is maintained by the native populations of animals. If you change one aspect of that balance, then it creates a domino effect.

Let’s say that we have an imaginary river, the River Sága, which is home to large, healthy beds of freshwater bivalves called blue purses (not a real bivalve). In this river there are also a few species of fish that go there to spawn and where the juvenile fish live until they’re big enough to move on. One day, an old fisherman dumps water into the River Sága from his boat and unknowingly releases several thousand eggs of the zebra mussel. A couple of years later, the river is no longer the same. The once-healthy beds of blue purses are now completely covered in smaller bivalves, smothering the native species. The water of the river is the clearest it’s ever been, but downstream there are enormous patches of algae, and there are no fish to be seen. What was once a nice fishing spot for man and animal alike is now barren, save for the zebra mussels and the algae.

Zebra mussels, like any invasive species, are horrible for the environments that they infiltrate because they have no natural predators, and they often outcompete the native species. Because zebra mussels are so good at filtering the water, it makes it easier for predators to find their prey in the water, whether it’s a larger fish or a bird hunting the juveniles that have spawned there. And because zebra mussels reproduce so much, they can easily smother their competitors, becoming the dominate species of the environment and changing it for the worse.

Zebra mussels also have an impact on human property. They have been known to block the drainage pipes of factories. They can incapacitate boats by clogging pipes and engines, or even by covering the sides of the boat and making it too heavy to float properly. It can take an absurd amount of money to remove them, and we have to do it often because they regularly come back and are so hard to eliminate.

I wanted to talk about zebra mussels because they have been noticed in the Chesapeake Bay, which is an important part of my life, and because it helps introduce the topic of invasive species. From what I understand, there is not much you can do once the zebra mussels appear, only that we must strive to prevent their spread elsewhere. But this also means that there is a potential opportunity for you, because maybe you can find a way to remove them from their nonnative habitats.

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